Advanced

Tutor model

i62 💰:9.4

i52 💰:7.9

🏆 i67 💰:62.5

i70 💰:125.0

i68 💰:125.0

🏆 i66 💰:75.0

i65 💰:125.0

i63 💰:62.5

i61 💰:75.0

i60 💰:9.4

i60 💰:37.5

i58 💰:62.5

i57 💰:22.5

i57 💰:37.5

i56 💰:45.0

⚡ i55 💰:11.25

i55 💰:37.5

i54 💰:62.5

i52 💰:35.0

i51 💰:37.5

i49 💰:15.0

i49 💰:62.5

i48 💰:11.3

i47 💰:7.5

i44 💰:25.0

i43 💰:37.5

i42 💰:187.5

i40 💰:5.0

i39 💰:100.0

i38 💰:37.5

i37 💰:11.0

i36 💰:187.5

i34 💰:12.5

i33 💰:37.5

i30 💰:1.0

i29 💰:1.5

i28 💰:150.0

i23 💰:20.0

i20 💰:4.0

i18 💰:1.0

i16 💰:25.0

i13 💰:1.5

Keep session private

What would you like to learn?

Override for the tutor's lesson content generation calls. Auto uses the system default (Claude Sonnet 5 for lesson text, Opus 5 for diagrams).

Lesson generation model

System default

i58 💰:18.8

i31 💰:11.0

i25 💰:31.3

Tutoring abilities

Drop a strip of magnesium into weak vinegar and it slowly bubbles for minutes, but drop it into concentrated hydrochloric acid and it violently fizzes away in seconds.

What is happening at the particle level to cause such a dramatic difference in speed?

For a chemical reaction to happen, reactant particles must collide with each other with at least a minimum energy called the **activation energy**.

**Concentration** measures the number of solute particles dissolved in a given volume of solution, usually in moles per cubic decimeter ($	ext{mol/dm}^3$).

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
      user-select: none;
    }

    body {
      background: #f8f9fa;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
      padding: 12px;
      gap: 12px;
    }

    .header-badge {
      font-size: 13px;
      font-weight: 600;
      color: #6b7280;
      background: #ffffff;
      padding: 4px 12px;
      border-radius: 20px;
      border: 1px solid #e5e7eb;
      box-shadow: 0 1px 2px rgba(0,0,0,0.04);
    }

    .containers-wrap {
      display: flex;
      flex-direction: row;
      justify-content: center;
      gap: 16px;
      width: 100%;
      max-width: 540px;
    }

    .vessel-card {
      flex: 1;
      background: #ffffff;
      border-radius: 12px;
      border: 1px solid #e5e7eb;
      box-shadow: 0 2px 6px rgba(0,0,0,0.05);
      padding: 12px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px;
    }

    .vessel-title {
      font-size: 14px;
      font-weight: 700;
      color: #1e2945;
      text-align: center;
    }

    .vessel-sub {
      font-size: 12px;
      font-weight: 600;
      color: #22b7ff;
    }

    .canvas-container {
      position: relative;
      width: 100%;
      aspect-ratio: 1 / 1.15;
      max-height: 220px;
      background: #f0f9ff;
      border: 2px solid #bae6fd;
      border-top: none;
      border-radius: 0 0 10px 10px;
      overflow: hidden;
    }

    canvas {
      width: 100%;
      height: 100%;
      display: block;
    }

    .rate-bar-container {
      width: 100%;
      background: #f3f4f6;
      border-radius: 6px;
      height: 8px;
      overflow: hidden;
      margin-top: 4px;
    }

    .rate-fill {
      height: 100%;
      border-radius: 6px;
      transition: width 0.3s ease;
    }

    .rate-fill.low {
      width: 30%;
      background: #38bdf8;
    }

    .rate-fill.high {
      width: 90%;
      background: #ef4444;
    }

    .rate-label {
      font-size: 11px;
      font-weight: 600;
      color: #6b7280;
    }

    @media (max-width: 380px) {
      .containers-wrap {
        gap: 8px;
      }
      .vessel-card {
        padding: 8px 6px;
      }
      .vessel-title {
        font-size: 12px;
      }
    }
  </style>
</head>
<body>

  <div class="header-badge">Equal Volume (1 dm³)</div>

  <div class="containers-wrap">
    
    <div class="vessel-card">
      <div class="vessel-title">Low Concentration</div>
      <div class="vessel-sub">1 mol/dm³</div>
      <div class="canvas-container">
        <canvas id="canvas-low"></canvas>
      </div>
      <div class="rate-bar-container">
        <div class="rate-fill low"></div>
      </div>
      <div class="rate-label">Fewer Collisions</div>
    </div>

    
    <div class="vessel-card">
      <div class="vessel-title">High Concentration</div>
      <div class="vessel-sub">3 mol/dm³</div>
      <div class="canvas-container">
        <canvas id="canvas-high"></canvas>
      </div>
      <div class="rate-bar-container">
        <div class="rate-fill high"></div>
      </div>
      <div class="rate-label">Frequent Collisions</div>
    </div>
  </div>

  <script>
    function setupSimulation(canvasId, particleCount, highlightColor) {
      const canvas = document.getElementById(canvasId);
      const ctx = canvas.getContext('2d');
      let dpr = window.devicePixelRatio || 1;
      let width, height;
      let flashes = [];

      function resize() {
        const rect = canvas.getBoundingClientRect();
        width = rect.width;
        height = rect.height;
        canvas.width = width * dpr;
        canvas.height = height * dpr;
        ctx.scale(dpr, dpr);
      }
      resize();
      window.addEventListener('resize', resize);

      const radius = 6;
      const speed = 1.3;
      let particles = [];

      for (let i = 0; i < particleCount; i++) {
        const angle = Math.random() * Math.PI * 2;
        particles.push({
          x: radius + Math.random() * (width - radius * 2),
          y: radius + Math.random() * (height - radius * 2),
          vx: Math.cos(angle) * speed,
          vy: Math.sin(angle) * speed,
          r: radius
        });
      }

      function update() {
        // Move & walls
        for (let i = 0; i < particles.length; i++) {
          let p = particles[i];
          p.x += p.vx;
          p.y += p.vy;

          if (p.x - p.r <= 0) {
            p.x = p.r;
            p.vx *= -1;
          } else if (p.x + p.r >= width) {
            p.x = width - p.r;
            p.vx *= -1;
          }

          if (p.y - p.r <= 0) {
            p.y = p.r;
            p.vy *= -1;
          } else if (p.y + p.r >= height) {
            p.y = height - p.r;
            p.vy *= -1;
          }
        }

        // Particle-particle collisions
        for (let i = 0; i < particles.length; i++) {
          for (let j = i + 1; j < particles.length; j++) {
            let p1 = particles[i];
            let p2 = particles[j];
            let dx = p2.x - p1.x;
            let dy = p2.y - p1.y;
            let dist = Math.hypot(dx, dy);

            if (dist < p1.r + p2.r && dist > 0) {
              // Elastic bounce
              let nx = dx / dist;
              let ny = dy / dist;
              let kx = p1.vx - p2.vx;
              let ky = p1.vy - p2.vy;
              let p = 2 * (nx * kx + ny * ky) / 2;

              p1.vx -= p * nx;
              p1.vy -= p * ny;
              p2.vx += p * nx;
              p2.vy += p * ny;

              // Separate
              let overlap = (p1.r + p2.r - dist) / 2;
              p1.x -= nx * overlap;
              p1.y -= ny * overlap;
              p2.x += nx * overlap;
              p2.y += ny * overlap;

              // Spark effect
              flashes.push({
                x: (p1.x + p2.x) / 2,
                y: (p1.y + p2.y) / 2,
                radius: 4,
                alpha: 1.0
              });
            }
          }
        }

        // Render
        ctx.clearRect(0, 0, width, height);

        // Draw collision flashes
        for (let i = flashes.length - 1; i >= 0; i--) {
          let f = flashes[i];
          ctx.beginPath();
          ctx.arc(f.x, f.y, f.radius, 0, Math.PI * 2);
          ctx.fillStyle = `rgba(239, 68, 68, ${f.alpha})`;
          ctx.fill();
          f.radius += 0.8;
          f.alpha -= 0.08;
          if (f.alpha <= 0) flashes.splice(i, 1);
        }

        // Draw particles
        for (let p of particles) {
          ctx.beginPath();
          ctx.arc(p.x, p.y, p.r, 0, Math.PI * 2);
          ctx.fillStyle = highlightColor;
          ctx.fill();
          ctx.strokeStyle = '#0284c7';
          ctx.lineWidth = 1.5;
          ctx.stroke();

          // Particle shine
          ctx.beginPath();
          ctx.arc(p.x - 2, p.y - 2, 1.5, 0, Math.PI * 2);
          ctx.fillStyle = 'rgba(255,255,255,0.8)';
          ctx.fill();
        }

        requestAnimationFrame(update);
      }

      requestAnimationFrame(update);
    }

    setupSimulation('canvas-low', 5, '#38bdf8');
    setupSimulation('canvas-high', 16, '#38bdf8');
  </script>
</body>
</html>

When you increase the concentration of an acid, there are more reactant particles crowded into the same volume.

This crowding makes collisions between acid particles and solid reactants occur more **frequently**, directly increasing the rate of reaction.

How do we measure this reaction speed accurately in a laboratory?

When magnesium reacts with hydrochloric acid, it produces magnesium chloride and releases hydrogen gas: $\text{Mg (s)} + 2\text{HCl (aq)} \rightarrow \text{MgCl}_2\text{ (aq)} + \text{H}_2\text{ (g)}$.

We can track the reaction rate by measuring the volume of hydrogen gas collected in a **gas syringe** at regular time intervals.

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="aspect-ratio" content="4:3">
<style>
  * { box-sizing: border-box; margin: 0; padding: 0; }
  body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: #ffffff;
    color: #1e2945;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    padding: 10px;
    user-select: none;
  }
  .controls {
    display: flex;
    gap: 8px;
    width: 100%;
    max-width: 520px;
    justify-content: center;
    margin-bottom: 6px;
  }
  button {
    font-size: 13px;
    font-weight: 600;
    padding: 6px 14px;
    border-radius: 20px;
    border: 1px solid #cbd5e1;
    background: #f8fafc;
    color: #475569;
    cursor: pointer;
    transition: all 0.2s ease;
  }
  button.active {
    background: #0284c7;
    color: #ffffff;
    border-color: #0284c7;
    box-shadow: 0 2px 8px rgba(2, 132, 199, 0.3);
  }
  button.play-btn {
    background: #10b981;
    color: white;
    border-color: #10b981;
  }
  button.play-btn.running {
    background: #64748b;
    border-color: #64748b;
  }
  svg {
    width: 100%;
    max-width: 540px;
    height: auto;
    overflow: visible;
  }
  .label {
    font-size: 11px;
    fill: #64748b;
    font-weight: 600;
  }
  .val-label {
    font-size: 12px;
    fill: #0f172a;
    font-weight: 700;
    font-variant-numeric: tabular-nums;
  }
  .axis-label {
    font-size: 10px;
    fill: #94a3b8;
  }
</style>
</head>
<body>

<div class="controls">
  <button id="btnLow" class="active" onclick="setConc(0.5)">0.5 M (Low)</button>
  <button id="btnHigh" onclick="setConc(2.0)">2.0 M (High)</button>
  <button id="btnPlay" class="play-btn" onclick="toggleRun()">▶ Run</button>
</div>

<svg viewBox="0 0 540 340">
  
  <path d="M 90 120 L 90 65 Q 90 55 100 55 L 210 55 Q 215 55 215 62 L 215 70" 
        fill="none" stroke="#94a3b8" stroke-width="6" stroke-linecap="round"/>
  <path d="M 90 120 L 90 65 Q 90 55 100 55 L 210 55 Q 215 55 215 62 L 215 70" 
        fill="none" stroke="#e0f2fe" stroke-width="2" stroke-linecap="round"/>

  
  <g transform="translate(210, 50)">
    
    <rect x="0" y="16" width="12" height="8" fill="#cbd5e1" rx="1"/>
    
    <rect id="gasFill" x="12" y="8" width="0" height="24" fill="#e0f2fe"/>
    
    
    <rect x="12" y="5" width="160" height="30" fill="none" stroke="#64748b" stroke-width="2" rx="2"/>
    <line x1="172" y1="0" x2="172" y2="40" stroke="#64748b" stroke-width="3"/>
    
    
    <path d="M 12 5 v 5 M 42 5 v 4 M 72 5 v 5 M 102 5 v 4 M 132 5 v 5 M 162 5 v 4" stroke="#94a3b8" stroke-width="1.5"/>
    <text x="12" y="2" class="axis-label" text-anchor="middle">0</text>
    <text x="72" y="2" class="axis-label" text-anchor="middle">20</text>
    <text x="132" y="2" class="axis-label" text-anchor="middle">40</text>
    <text x="162" y="2" class="axis-label" text-anchor="middle">cm³</text>
    
    
    <g id="plunger" transform="translate(12, 0)">
      <rect x="0" y="6" width="6" height="28" fill="#0284c7" rx="1"/>
      <rect x="6" y="16" width="80" height="8" fill="#94a3b8"/>
      <rect x="86" y="8" width="5" height="24" fill="#64748b" rx="2"/>
    </g>
    <text x="90" y="48" class="label" text-anchor="middle">Gas Syringe</text>
  </g>

  
  <g transform="translate(40, 110)">
    
    <path d="M 28 85 L 12 145 Q 10 150 16 150 L 84 150 Q 90 150 88 145 L 72 85 Z" fill="#e0f2fe"/>
    
    
    <rect x="38" y="142" width="24" height="5" fill="#64748b" rx="1.5"/>
    
    
    <g id="bubbles"></g>
    
    
    <path d="M 40 20 L 40 55 L 12 145 Q 8 155 20 155 L 80 155 Q 92 155 88 145 L 60 55 L 60 20 Z" 
          fill="none" stroke="#64748b" stroke-width="2.5" stroke-linejoin="round"/>
    
    <ellipse cx="50" cy="20" rx="12" ry="3" fill="none" stroke="#64748b" stroke-width="2"/>
    
    <path d="M 41 20 L 43 36 L 57 36 L 59 20 Z" fill="#475569"/>

    <text x="50" y="172" class="label" text-anchor="middle">HCl + Mg</text>
  </g>

  <text x="145" y="45" class="label" text-anchor="middle">Delivery Tube</text>

  
  <g transform="translate(240, 150)">
    <rect x="0" y="0" width="260" height="150" fill="#f8fafc" rx="8" stroke="#e2e8f0"/>
    
    
    <line x1="40" y1="125" x2="245" y2="125" stroke="#94a3b8" stroke-width="1.5"/>
    <line x1="40" y1="20" x2="40" y2="125" stroke="#94a3b8" stroke-width="1.5"/>
    
    
    <text x="245" y="140" class="axis-label" text-anchor="end">Time</text>
    <text x="35" y="25" class="axis-label" text-anchor="end">Vol</text>
    
    
    <line x1="40" y1="35" x2="240" y2="35" stroke="#e2e8f0" stroke-dasharray="3 3"/>
    <text x="35" y="38" class="axis-label" text-anchor="end">max</text>

    
    <path id="curveLowRef" fill="none" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="2 2" opacity="0.4"/>
    <path id="curveHighRef" fill="none" stroke="#0284c7" stroke-width="1.5" stroke-dasharray="2 2" opacity="0.4"/>
    <path id="activeCurve" fill="none" stroke="#0284c7" stroke-width="3" stroke-linecap="round"/>
    
    
    <circle id="trackDot" cx="40" cy="125" r="4" fill="#0284c7" opacity="0"/>
    
    
    <text id="volText" x="140" y="32" class="val-label" text-anchor="start">0 cm³</text>
  </g>
</svg>

<script>
  let conc = 0.5;
  let running = false;
  let animId = null;
  let progress = 0; // 0 to 1

  const maxVolPx = 150; // max syringe travel
  const graphW = 195;
  const graphH = 90;
  const graphX0 = 40;
  const graphY0 = 125;

  const btnLow = document.getElementById('btnLow');
  const btnHigh = document.getElementById('btnHigh');
  const btnPlay = document.getElementById('btnPlay');
  const plunger = document.getElementById('plunger');
  const gasFill = document.getElementById('gasFill');
  const activeCurve = document.getElementById('activeCurve');
  const trackDot = document.getElementById('trackDot');
  const volText = document.getElementById('volText');
  const bubblesG = document.getElementById('bubbles');

  function getK() {
    return conc === 2.0 ? 5.5 : 1.6;
  }

  function getVolFraction(t) {
    const k = getK();
    return 1 - Math.exp(-k * t);
  }

  function setConc(val) {
    if (running) toggleRun();
    conc = val;
    btnLow.classList.toggle('active', conc === 0.5);
    btnHigh.classList.toggle('active', conc === 2.0);
    const color = conc === 2.0 ? '#0284c7' : '#64748b';
    activeCurve.setAttribute('stroke', color);
    trackDot.setAttribute('fill', color);
    resetSimulation();
  }

  function resetSimulation() {
    progress = 0;
    plunger.setAttribute('transform', `translate(12, 0)`);
    gasFill.setAttribute('width', 0);
    activeCurve.setAttribute('d', '');
    trackDot.setAttribute('opacity', 0);
    volText.textContent = '0 cm³';
    bubblesG.innerHTML = '';
  }

  function toggleRun() {
    running = !running;
    if (running) {
      if (progress >= 1) resetSimulation();
      btnPlay.textContent = '⏸ Pause';
      btnPlay.classList.add('running');
      lastTime = performance.now();
      animLoop();
    } else {
      btnPlay.textContent = '▶ Run';
      btnPlay.classList.remove('running');
      cancelAnimationFrame(animId);
    }
  }

  let lastTime = 0;
  function animLoop(now = performance.now()) {
    if (!running) return;
    const dt = (now - lastTime) / 1000;
    lastTime = now;

    // Advance progress (total duration: ~6s)
    progress += dt / 5.5;
    if (progress >= 1) progress = 1;

    const vFrac = getVolFraction(progress);
    const curVolCm3 = Math.round(vFrac * 50);

    // Update Syringe
    const disp = vFrac * maxVolPx;
    plunger.setAttribute('transform', `translate(${12 + disp}, 0)`);
    gasFill.setAttribute('width', disp);
    volText.textContent = `${curVolCm3} cm³`;

    // Update Graph Path
    let pathD = `M ${graphX0} ${graphY0}`;
    const steps = Math.floor(progress * 50);
    for (let i = 1; i <= steps; i++) {
      const p = i / 50 * progress;
      const x = graphX0 + p * graphW;
      const y = graphY0 - getVolFraction(p) * graphH;
      pathD += ` L ${x.toFixed(1)} ${y.toFixed(1)}`;
    }
    const curX = graphX0 + progress * graphW;
    const curY = graphY0 - vFrac * graphH;
    pathD += ` L ${curX.toFixed(1)} ${curY.toFixed(1)}`;
    activeCurve.setAttribute('d', pathD);

    // Update Tracker Dot
    trackDot.setAttribute('cx', curX);
    trackDot.setAttribute('cy', curY);
    trackDot.setAttribute('opacity', 1);

    // Bubbles generation (higher rate when rate of reaction is higher)
    const rate = Math.exp(-getK() * progress) * (conc === 2.0 ? 1.0 : 0.35);
    if (Math.random() < rate * 0.9) {
      createBubble();
    }
    updateBubbles();

    if (progress < 1) {
      animId = requestAnimationFrame(animLoop);
    } else {
      running = false;
      btnPlay.textContent = '↺ Reset';
      btnPlay.classList.remove('running');
    }
  }

  let bubbles = [];
  function createBubble() {
    const b = {
      x: 40 + Math.random() * 20,
      y: 140,
      r: 1.5 + Math.random() * 2,
      speed: 0.8 + Math.random() * 1.2
    };
    bubbles.push(b);
  }

  function updateBubbles() {
    bubbles.forEach(b => b.y -= b.speed);
    bubbles = bubbles.filter(b => b.y > 88);
    let svgStr = '';
    bubbles.forEach(b => {
      svgStr += `<circle cx="${b.x.toFixed(1)}" cy="${b.y.toFixed(1)}" r="${b.r.toFixed(1)}" fill="#0284c7" opacity="0.6"/>`;
    });
    bubblesG.innerHTML = svgStr;
  }

  // Pre-render reference dashed curves for comparison
  function buildRefCurves() {
    let dLow = `M ${graphX0} ${graphY0}`, dHigh = `M ${graphX0} ${graphY0}`;
    for (let i = 1; i <= 50; i++) {
      const p = i / 50;
      const x = graphX0 + p * graphW;
      const yL = graphY0 - (1 - Math.exp(-1.6 * p)) * graphH;
      const yH = graphY0 - (1 - Math.exp(-5.5 * p)) * graphH;
      dLow += ` L ${x.toFixed(1)} ${yL.toFixed(1)}`;
      dHigh += ` L ${x.toFixed(1)} ${yH.toFixed(1)}`;
    }
    document.getElementById('curveLowRef').setAttribute('d', dLow);
    document.getElementById('curveHighRef').setAttribute('d', dHigh);
  }
  buildRefCurves();
  setConc(0.5);
</script>
</body>
</html>

To keep the test fair, we vary only the **independent variable** (acid concentration) while keeping the **controlled variables** strictly constant.

Key controlled variables include: the **volume of acid** (e.g., $50\text{ cm}^3$), the **mass and surface area of magnesium** (e.g., identical $3\text{ cm}$ ribbon strips), and the **room temperature**.

What happens if our solid reactant is marble chips instead of magnesium ribbon?

Marble chips are calcium carbonate ($\text{CaCO}_3$), which react with hydrochloric acid to produce dense carbon dioxide gas: $\text{CaCO}_3\text{ (s)} + 2\text{HCl (aq)} \rightarrow \text{CaCl}_2\text{ (aq)} + \text{H}_2\text{O (l)} + \text{CO}_2\text{ (g)}$.

Because carbon dioxide gas escapes into the air, the total mass of the reaction mixture steadily decreases over time.

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Concentration and Reaction Rate</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; }
    body {
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 12px;
      user-select: none;
    }

    /* Controls Header */
    .controls {
      display: flex;
      gap: 8px;
      justify-content: center;
      width: 100%;
      max-width: 500px;
      margin-bottom: 6px;
    }
    .btn {
      flex: 1;
      padding: 8px 12px;
      font-size: 13px;
      font-weight: 600;
      border-radius: 8px;
      border: 1px solid #e2e8f0;
      background: #f8fafc;
      color: #64748b;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      transition: all 0.2s ease;
    }
    .btn.active {
      background: #06b6d4;
      color: #ffffff;
      border-color: #0891b2;
      box-shadow: 0 2px 6px rgba(6, 182, 212, 0.25);
    }

    /* Main Display Area */
    .sim-container {
      display: flex;
      flex-direction: row;
      align-items: center;
      justify-content: space-around;
      width: 100%;
      max-width: 560px;
      flex: 1;
      gap: 12px;
    }

    /* Flask & Balance Visual */
    .apparatus-col {
      display: flex;
      flex-direction: column;
      align-items: center;
      position: relative;
      width: 48%;
      max-width: 220px;
    }

    .gas-escape {
      position: absolute;
      top: 6px;
      display: flex;
      gap: 6px;
      pointer-events: none;
    }
    .bubble-trail {
      font-size: 11px;
      font-weight: 700;
      color: #0891b2;
      opacity: 0;
      transform: translateY(0);
      animation: floatUp 1.2s infinite ease-out;
    }
    .bubble-trail:nth-child(2) { animation-delay: 0.4s; }
    .bubble-trail:nth-child(3) { animation-delay: 0.8s; }

    @keyframes floatUp {
      0% { opacity: 0; transform: translateY(4px); }
      40% { opacity: 0.85; }
      100% { opacity: 0; transform: translateY(-24px); }
    }

    .flask-svg {
      width: 100%;
      height: 180px;
    }

    /* Digital Balance */
    .balance-box {
      width: 100%;
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      border-radius: 8px;
      padding: 6px 12px;
      margin-top: -6px;
      display: flex;
      flex-direction: column;
      align-items: center;
      box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
      z-index: 2;
    }
    .pan {
      width: 85%;
      height: 4px;
      background: #94a3b8;
      border-radius: 2px;
      margin-bottom: 5px;
    }
    .lcd-display {
      background: #0f172a;
      color: #38bdf8;
      font-family: monospace;
      font-size: 17px;
      font-weight: 700;
      padding: 3px 10px;
      border-radius: 4px;
      letter-spacing: 1px;
      box-shadow: inset 0 1px 3px rgba(0,0,0,0.6);
    }
    .balance-label {
      font-size: 11px;
      color: #64748b;
      font-weight: 600;
      margin-top: 2px;
    }

    /* Graph Column */
    .graph-col {
      width: 50%;
      max-width: 250px;
      display: flex;
      flex-direction: column;
      align-items: center;
    }
    .graph-svg {
      width: 100%;
      height: 190px;
      background: #f8fafc;
      border-radius: 8px;
      border: 1px solid #e2e8f0;
    }

    /* Action bar */
    .play-btn {
      width: 100%;
      max-width: 280px;
      padding: 8px 16px;
      background: #1e2945;
      color: #ffffff;
      border: none;
      border-radius: 8px;
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      margin-top: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      transition: background 0.15s ease;
    }
    .play-btn:active {
      background: #0f172a;
    }

    /* Labels */
    .label-tag {
      font-size: 11px;
      font-weight: 600;
      fill: #475569;
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button class="btn active" id="btnHigh" onclick="setConc('high')">
      <span>●</span> 2 mol/dm³ (High)
    </button>
    <button class="btn" id="btnLow" onclick="setConc('low')">
      <span>○</span> 1 mol/dm³ (Low)
    </button>
  </div>

  <div class="sim-container">
    
    <div class="apparatus-col">
      <div class="gas-escape" id="gasEscape">
        <span class="bubble-trail">CO₂↑</span>
        <span class="bubble-trail">CO₂↑</span>
        <span class="bubble-trail">CO₂↑</span>
      </div>

      <svg class="flask-svg" viewBox="0 0 160 180">
        
        <ellipse cx="80" cy="30" rx="14" ry="9" fill="#e2e8f0" stroke="#cbd5e1" stroke-width="2"/>
        <text x="80" y="18" text-anchor="middle" class="label-tag">Cotton wool</text>
        <line x1="80" y1="21" x2="80" y2="25" stroke="#94a3b8" stroke-width="1.5"/>

        
        <path d="M 66,32 L 66,60 L 22,145 A 8,8 0 0,0 29,156 L 131,156 A 8,8 0 0,0 138,145 L 94,60 L 94,32 Z" 
              fill="none" stroke="#64748b" stroke-width="3" stroke-linejoin="round"/>
        
        
        <path d="M 40,115 L 120,115 L 134,148 A 6,6 0 0,1 128,154 L 32,154 A 6,6 0 0,1 26,148 Z" 
              fill="#cffafe" opacity="0.8"/>
        <line x1="38" y1="115" x2="122" y2="115" stroke="#06b6d4" stroke-width="1.5" stroke-dasharray="3,2"/>

        
        <rect x="52" y="143" width="12" height="7" rx="2" fill="#94a3b8"/>
        <rect x="74" y="145" width="14" height="6" rx="2" fill="#cbd5e1"/>
        <rect x="96" y="142" width="11" height="8" rx="2" fill="#94a3b8"/>
        <rect x="66" y="148" width="10" height="5" rx="1" fill="#64748b"/>

        
        <g id="reactionBubbles">
          <circle cx="58" cy="135" r="2" fill="#0891b2" opacity="0.6"/>
          <circle cx="80" cy="128" r="2.5" fill="#0891b2" opacity="0.7"/>
          <circle cx="102" cy="138" r="1.8" fill="#0891b2" opacity="0.6"/>
          <circle cx="70" cy="138" r="1.5" fill="#0891b2" opacity="0.5"/>
          <circle cx="90" cy="130" r="2" fill="#0891b2" opacity="0.6"/>
        </g>

        
        <text x="80" y="172" text-anchor="middle" class="label-tag">Acid + CaCO₃</text>
      </svg>

      
      <div class="balance-box">
        <div class="pan"></div>
        <div class="lcd-display" id="massDisplay">125.00 g</div>
        <div class="balance-label">Digital balance</div>
      </div>
    </div>

    
    <div class="graph-col">
      <svg class="graph-svg" id="graphSvg" viewBox="0 0 200 170">
        
        <line x1="40" y1="20" x2="185" y2="20" stroke="#e2e8f0" stroke-width="1" stroke-dasharray="2,2"/>
        <line x1="40" y1="75" x2="185" y2="75" stroke="#e2e8f0" stroke-width="1" stroke-dasharray="2,2"/>
        <line x1="40" y1="130" x2="185" y2="130" stroke="#e2e8f0" stroke-width="1"/>
        <line x1="40" y1="20" x2="40" y2="130" stroke="#e2e8f0" stroke-width="1"/>

        
        <line x1="38" y1="130" x2="190" y2="130" stroke="#64748b" stroke-width="1.5"/>
        <line x1="40" y1="132" x2="40" y2="15" stroke="#64748b" stroke-width="1.5"/>

        
        <text x="40" y="12" text-anchor="middle" class="label-tag">Mass (g)</text>
        <text x="180" y="144" text-anchor="end" class="label-tag">Time (s)</text>

        <text x="34" y="24" text-anchor="end" font-size="9" fill="#94a3b8">125</text>
        <text x="34" y="130" text-anchor="end" font-size="9" fill="#94a3b8">123</text>

        
        <path id="refTrace" d="" fill="none" stroke="#cbd5e1" stroke-width="2" stroke-dasharray="3,3"/>

        
        <path id="activeCurve" d="M 40,20" fill="none" stroke="#06b6d4" stroke-width="3" stroke-linecap="round"/>
        
        
        <circle id="graphDot" cx="40" cy="20" r="4" fill="#0891b2" stroke="#ffffff" stroke-width="1.5"/>
      </svg>
    </div>
  </div>

  
  <button class="play-btn" id="runBtn" onclick="toggleRun()">
    <span id="runIcon">▶</span> <span id="runText">Start Reaction</span>
  </button>

  <script>
    let mode = 'high'; // 'high' | 'low'
    let isRunning = false;
    let animTimer = null;
    let progress = 0; // 0 to 1

    const massDisplay = document.getElementById('massDisplay');
    const activeCurve = document.getElementById('activeCurve');
    const refTrace = document.getElementById('refTrace');
    const graphDot = document.getElementById('graphDot');
    const gasEscape = document.getElementById('gasEscape');
    const runText = document.getElementById('runText');
    const runIcon = document.getElementById('runIcon');

    function setConc(newMode) {
      if (mode === newMode && isRunning) return;
      mode = newMode;
      document.getElementById('btnHigh').classList.toggle('active', mode === 'high');
      document.getElementById('btnLow').classList.toggle('active', mode === 'low');
      resetSim();
      startSim();
    }

    function toggleRun() {
      if (isRunning) {
        resetSim();
      } else {
        startSim();
      }
    }

    function resetSim() {
      clearInterval(animTimer);
      isRunning = false;
      progress = 0;
      runText.textContent = "Start Reaction";
      runIcon.textContent = "▶";
      gasEscape.style.display = "none";
      updateState(0);
    }

    function startSim() {
      resetSim();
      isRunning = true;
      runText.textContent = "Reset";
      runIcon.textContent = "↺";
      gasEscape.style.display = "flex";

      // Animation loop
      const startTime = Date.now();
      const duration = mode === 'high' ? 4000 : 7000;

      animTimer = setInterval(() => {
        const elapsed = Date.now() - startTime;
        progress = Math.min(elapsed / duration, 1);

        updateState(progress);

        if (progress >= 1) {
          clearInterval(animTimer);
          gasEscape.style.display = "none";
          runText.textContent = "Replay";
          runIcon.textContent = "↺";
        }
      }, 30);
    }

    function getMassLoss(t, isHigh) {
      // Exponential decay approach: Mass loss reaches ~2.00g max
      const k = isHigh ? 3.5 : 1.2;
      return 2.00 * (1 - Math.exp(-k * t));
    }

    function updateState(p) {
      const isHigh = mode === 'high';
      const maxT = 1.0;
      const t = p * maxT;
      
      const massLoss = getMassLoss(t, isHigh);
      const currentMass = (125.00 - massLoss).toFixed(2);
      massDisplay.textContent = `${currentMass} g`;

      // Build curve path coordinates
      const startX = 40;
      const endX = 185;
      const startY = 20; // 125g
      const maxLossY = 110; // 123g (2g loss mapped to 90px)

      let pathD = `M ${startX},${startY}`;
      const steps = 30;
      for (let i = 1; i <= steps * p; i++) {
        const stepP = i / steps;
        const x = startX + stepP * (endX - startX);
        const loss = getMassLoss(stepP, isHigh);
        const y = startY + (loss / 2.00) * (maxLossY - startY);
        pathD += ` L ${x.toFixed(1)},${y.toFixed(1)}`;
      }

      activeCurve.setAttribute('d', pathD);
      
      const currX = startX + p * (endX - startX);
      const currY = startY + (massLoss / 2.00) * (maxLossY - startY);
      graphDot.setAttribute('cx', currX);
      graphDot.setAttribute('cy', currY);

      // Comparison ghost trace for the other concentration
      let otherD = `M ${startX},${startY}`;
      for (let i = 1; i <= steps; i++) {
        const stepP = i / steps;
        const x = startX + stepP * (endX - startX);
        const loss = getMassLoss(stepP, !isHigh);
        const y = startY + (loss / 2.00) * (maxLossY - startY);
        otherD += ` L ${x.toFixed(1)},${y.toFixed(1)}`;
      }
      refTrace.setAttribute('d', otherD);
    }

    // Initialize initial state
    updateState(0);
    gasEscape.style.display = "none";
  </script>
</body>
</html>

A **cotton wool plug** is placed in the neck of the flask to allow carbon dioxide gas to escape while preventing corrosive acid droplets from splashing out.

Once you collect volume or mass data over time, how do you mathematically calculate the reaction rate?

Plotting gas volume on the y-axis against time on the x-axis produces a curve that is steepest at the start and gradually levels off to a plateau.

The **mean rate** of reaction is calculated across an interval using: $\text{Mean Rate} = \frac{\text{Quantity of reactant used or product formed}}{\text{Time taken}}$.

The **mean rate** of reaction over any time period is calculated using: $\text{Mean Rate} = \frac{\text{Quantity of reactant used or product formed}}{\text{Time taken}}$.

To find the rate at a specific time, draw a **tangent** to the curve and calculate its gradient: $\text{Rate} = \frac{\Delta y}{\Delta x}$.

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, sans-serif;
      color: #1e2945;
      background: transparent;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      width: 100%;
      padding: 8px;
      user-select: none;
    }
    .controls {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
      justify-content: center;
      align-items: center;
      width: 100%;
      max-width: 520px;
      margin-bottom: 6px;
    }
    .btn-group {
      display: flex;
      background: #f1f5f9;
      padding: 2px;
      border-radius: 6px;
      gap: 2px;
    }
    button {
      border: none;
      background: transparent;
      padding: 5px 10px;
      font-size: 13px;
      font-weight: 600;
      color: #64748b;
      border-radius: 4px;
      cursor: pointer;
      transition: all 0.2s ease;
    }
    button.active-high {
      background: #2563eb;
      color: #fff;
    }
    button.active-low {
      background: #9333ea;
      color: #fff;
    }
    .slider-container {
      display: flex;
      align-items: center;
      gap: 8px;
      font-size: 13px;
      font-weight: 600;
      color: #475569;
    }
    input[type="range"] {
      width: 130px;
      cursor: pointer;
      accent-color: #dc2626;
    }
    .graph-container {
      width: 100%;
      max-width: 520px;
      position: relative;
    }
    svg {
      width: 100%;
      height: auto;
      display: block;
      overflow: visible;
    }
    .axis-label {
      font-size: 11px;
      fill: #64748b;
      font-weight: 600;
    }
    .tick-label {
      font-size: 9.5px;
      fill: #94a3b8;
    }
    .metric-badge {
      font-size: 12px;
      font-weight: 700;
      fill: #dc2626;
    }
    .legend-text {
      font-size: 11px;
      font-weight: 600;
    }
  </style>
</head>
<body>

  <div class="controls">
    <div class="btn-group">
      <button id="btnHigh" class="active-high" onclick="setConc('high')">2.0 mol/dm³</button>
      <button id="btnLow" onclick="setConc('low')">1.0 mol/dm³</button>
    </div>
    <div class="slider-container">
      <span>Time: <span id="timeVal">15</span>s</span>
      <input type="range" id="timeSlider" min="2" max="90" value="15" step="1" oninput="updateTime(this.value)">
    </div>
  </div>

  <div class="graph-container">
    <svg viewBox="0 0 440 300" id="svgGraph">
      
      <g stroke="#f1f5f9" stroke-width="1">
        <line x1="50" y1="40" x2="410" y2="40" />
        <line x1="50" y1="90" x2="410" y2="90" />
        <line x1="50" y1="140" x2="410" y2="140" />
        <line x1="50" y1="190" x2="410" y2="190" />
        <line x1="140" y1="40" x2="140" y2="240" />
        <line x1="230" y1="40" x2="230" y2="240" />
        <line x1="320" y1="40" x2="320" y2="240" />
        <line x1="410" y1="40" x2="410" y2="240" />
      </g>

      
      <line x1="50" y1="40" x2="410" y2="40" stroke="#94a3b8" stroke-width="1.5" stroke-dasharray="3,3" />
      <text x="315" y="34" fill="#64748b" font-size="10" font-weight="600">Same max volume (limiting solid)</text>

      
      <line x1="50" y1="240" x2="415" y2="240" stroke="#64748b" stroke-width="1.5" />
      <line x1="50" y1="240" x2="50" y2="25" stroke="#64748b" stroke-width="1.5" />

      
      <text x="42" y="243" class="tick-label" text-anchor="end">0</text>
      <text x="42" y="193" class="tick-label" text-anchor="end">25</text>
      <text x="42" y="143" class="tick-label" text-anchor="end">50</text>
      <text x="42" y="93" class="tick-label" text-anchor="end">75</text>
      <text x="42" y="43" class="tick-label" text-anchor="end">100</text>

      
      <text x="50" y="255" class="tick-label" text-anchor="middle">0</text>
      <text x="140" y="255" class="tick-label" text-anchor="middle">25</text>
      <text x="230" y="255" class="tick-label" text-anchor="middle">50</text>
      <text x="320" y="255" class="tick-label" text-anchor="middle">75</text>
      <text x="410" y="255" class="tick-label" text-anchor="middle">100</text>

      
      <text x="230" y="272" class="axis-label" text-anchor="middle">Time (s)</text>
      <text x="-135" y="15" class="axis-label" text-anchor="middle" transform="rotate(-90)">Gas Volume (cm³)</text>

      
      <path id="curveLow" fill="none" stroke="#9333ea" stroke-width="2.5" stroke-linecap="round" opacity="0.4" />
      <path id="curveHigh" fill="none" stroke="#2563eb" stroke-width="2.5" stroke-linecap="round" />

      
      <polygon id="gradTriangle" fill="rgba(220, 38, 38, 0.12)" stroke="none" />
      <line id="dxLine" stroke="#dc2626" stroke-width="1.5" stroke-dasharray="2,2" />
      <line id="dyLine" stroke="#dc2626" stroke-width="1.5" stroke-dasharray="2,2" />

      
      <line id="tangentLine" stroke="#dc2626" stroke-width="2.2" stroke-linecap="round" />

      
      <circle id="tangentPoint" r="4.5" fill="#dc2626" stroke="#ffffff" stroke-width="1.5" />

      
      <text id="dxText" fill="#dc2626" font-size="10.5" font-weight="700" text-anchor="middle">Δx</text>
      <text id="dyText" fill="#dc2626" font-size="10.5" font-weight="700" text-anchor="start">Δy</text>

      
      <rect x="58" y="50" width="165" height="42" rx="4" fill="rgba(255, 255, 255, 0.92)" stroke="#e2e8f0" stroke-width="1" />
      <text x="66" y="66" font-size="10" fill="#64748b" font-weight="600">Rate = Gradient (Δy / Δx)</text>
      <text x="66" y="83" id="rateReadout" class="metric-badge">Rate: 3.2 cm³/s</text>

      
      <g transform="translate(260, 195)">
        <rect width="145" height="38" rx="4" fill="rgba(255, 255, 255, 0.9)" stroke="#e2e8f0" />
        <circle cx="12" cy="13" r="4" fill="#2563eb" />
        <text x="22" y="16" class="legend-text" fill="#1e2945">2.0 M (Fast)</text>
        <circle cx="12" cy="27" r="4" fill="#9333ea" />
        <text x="22" y="30" class="legend-text" fill="#1e2945">1.0 M (Slow)</text>
      </g>
    </svg>
  </div>

  <script>
    const ORIGIN_X = 50;
    const ORIGIN_Y = 240;
    const SCALE_X = 3.6; // 100s = 360px
    const SCALE_Y = 2.0; // 100cm³ = 200px
    const V_MAX = 100;

    let currentConc = 'high';
    let currentTime = 15;

    const kValues = {
      high: 0.052,
      low: 0.021
    };

    function vAt(t, k) {
      return V_MAX * (1 - Math.exp(-k * t));
    }

    function slopeAt(t, k) {
      return k * V_MAX * Math.exp(-k * t);
    }

    function generatePath(k) {
      let d = `M ${ORIGIN_X} ${ORIGIN_Y}`;
      for (let t = 1; t <= 100; t += 1) {
        const x = ORIGIN_X + t * SCALE_X;
        const y = ORIGIN_Y - vAt(t, k) * SCALE_Y;
        d += ` L ${x.toFixed(1)} ${y.toFixed(1)}`;
      }
      return d;
    }

    function initPaths() {
      document.getElementById('curveHigh').setAttribute('d', generatePath(kValues.high));
      document.getElementById('curveLow').setAttribute('d', generatePath(kValues.low));
    }

    function update() {
      const k = kValues[currentConc];
      const t = currentTime;
      const v = vAt(t, k);
      const m = slopeAt(t, k); // gradient in cm³/s

      const px = ORIGIN_X + t * SCALE_X;
      const py = ORIGIN_Y - v * SCALE_Y;

      // Contact point
      const pt = document.getElementById('tangentPoint');
      pt.setAttribute('cx', px);
      pt.setAttribute('cy', py);

      // Tangent line endpoints
      const dtSpan = Math.min(22, Math.max(12, 40 / (m + 0.5))); 
      const t1 = Math.max(0, t - dtSpan);
      const t2 = Math.min(100, t + dtSpan);

      const v1 = v + m * (t1 - t);
      const v2 = v + m * (t2 - t);

      const x1 = ORIGIN_X + t1 * SCALE_X;
      const y1 = ORIGIN_Y - v1 * SCALE_Y;
      const x2 = ORIGIN_X + t2 * SCALE_X;
      const y2 = ORIGIN_Y - v2 * SCALE_Y;

      const tangent = document.getElementById('tangentLine');
      tangent.setAttribute('x1', x1);
      tangent.setAttribute('y1', y1);
      tangent.setAttribute('x2', x2);
      tangent.setAttribute('y2', y2);

      // Gradient triangle
      const triX1 = x1;
      const triY1 = y1;
      const triX2 = x2;
      const triY2 = y2;
      const cornerX = x2;
      const cornerY = y1;

      document.getElementById('gradTriangle').setAttribute('points', `${triX1},${triY1} ${cornerX},${cornerY} ${triX2},${triY2}`);
      
      const dxLine = document.getElementById('dxLine');
      dxLine.setAttribute('x1', triX1);
      dxLine.setAttribute('y1', cornerY);
      dxLine.setAttribute('x2', cornerX);
      dxLine.setAttribute('y2', cornerY);

      const dyLine = document.getElementById('dyLine');
      dyLine.setAttribute('x1', cornerX);
      dyLine.setAttribute('y1', cornerY);
      dyLine.setAttribute('x2', triX2);
      dyLine.setAttribute('y2', triY2);

      const dxText = document.getElementById('dxText');
      dxText.setAttribute('x', (triX1 + cornerX) / 2);
      dxText.setAttribute('y', cornerY + 12);
      dxText.textContent = `Δt = ${(t2 - t1).toFixed(0)}s`;

      const dyText = document.getElementById('dyText');
      dyText.setAttribute('x', cornerX + 4);
      dyText.setAttribute('y', (cornerY + triY2) / 2 + 3);
      dyText.textContent = `ΔV = ${(v2 - v1).toFixed(1)}`;

      // Readout
      document.getElementById('rateReadout').textContent = `Rate: ${m.toFixed(2)} cm³/s`;
      document.getElementById('timeVal').textContent = t;

      // Active styling
      if (currentConc === 'high') {
        document.getElementById('curveHigh').setAttribute('opacity', '1');
        document.getElementById('curveLow').setAttribute('opacity', '0.3');
      } else {
        document.getElementById('curveHigh').setAttribute('opacity', '0.3');
        document.getElementById('curveLow').setAttribute('opacity', '1');
      }
    }

    function setConc(conc) {
      currentConc = conc;
      document.getElementById('btnHigh').className = conc === 'high' ? 'active-high' : '';
      document.getElementById('btnLow').className = conc === 'low' ? 'active-low' : '';
      update();
    }

    function updateTime(val) {
      currentTime = parseFloat(val);
      update();
    }

    initPaths();
    update();
  </script>
</body>
</html>

Notice that both acid concentrations eventually produce the exact same total gas volume if the solid reactant is in limiting supply, but the higher concentration reaches the end point much faster.

Why do students often lose marks on this practical in exam questions?

The single biggest source of experimental error is gas escaping into the room between adding the solid and inserting the rubber bung.

To prevent gas loss, place the magnesium inside a small glass specimen vial upright in the acid, insert the bung tightly, and shake the flask to start the reaction without opening it.

A common mistake in rate calculations is confusing **collision rate** with **collision energy** — changing concentration changes how often particles hit each other, not how hard they hit.

Whenever you explain concentration on an exam, always pair the words 'more particles per unit volume' with 'greater frequency of successful collisions'.

science

Investigating Concentration Effects on Reaction Rate. Plan and execute investigations into the effect of changing acid concentration on reaction rate using magnesium or marble chips.

The Rate of Reaction of Magnesium with Hydrochloric Acid: Practical Class Activity & Technician Guide

GCSE Chemistry (Single Science): Rates of Reaction and Required Practical Methods

AQA GCSE Chemistry Required Practical: Investigating the Effect of Concentration on Rate of Reaction

Pedagogical strategy focuses on dual-track mastery: (1) Procedural competency in assembling gas collection apparatus, systematically varying acid concentration while controlling mass/surface area and temperature, and minimising gas leakage when inserting the stopper; and (2) Mathematical and conceptual mastery in applying collision theory terminology ('collision frequency' rather than 'number of collisions') and extracting instantaneous rates from curved graphs using tangents ($\text{gradient} = \frac{\Delta y}{\Delta x}$).

Investigating Concentration Effects on Reaction Rate

Collision Theory and Concentration

The Gas Syringe Method