Concentration: Collision Theory 🔗
- Concentration is easily thought of like raro - the more raro particles you add to your drink, the stronger it is!
- The more particles there are, the higher the chance there is of particles bumping into each other
- The more bumps there are, the greater number of reactions
- It does not increase the probability of successful collisions
Tauria / Example 🔗
Say 10% of collisions result in a successful reaction between two particles.
If 1000 collisions happen, there should be $1000 \times 0.1 = 100$ successful reactions
Since concentration doesn’t change the probability (10%), it only changes the number of collisions. $5000 \times 0.1 = 500$ successful reactions.
Matapaki / Discussion 🔗
Why does changing the concentration not change the probability of a successful reaction?
Think of the two things required for a reaction to occur!
Whakatika 🔗
Changing temperature does not affect the probability of a successful reaction because it does not change:
- the activation energy,
- the kinetic energy of the particles (temperature/speed),
- or the likelihood that they collide in the correct orientation.
Dilutions 🔗
- To change the concentration we must dilute one of our reactants.
- Pātai: What do we dilute raro with?
- Whakatika: Water! $H_{2}O$
- Pātai: Why do we dilute only one reactant?
- Whakatika: To ensure we are changing only one thing in our experiment so it is a fair test!
Dilutions Explained 🔗
- In Year 11 we will do dilutions in percentages. For example, 90% $HCl$, 50% $HCl$ or 30% $HCl$
- For $10ml$ of 80% $HCl$ this means 80% of the $10ml$ is $HCl$ and 20% is water!
$\text{Volume} = \frac{percentage}{100} \times \text{total volume}$
Pātai: Calculate the volumes of each solution 🔗
$\text{Volume of Acid} = \frac{percentage}{100} \times \text{total volume}$
| Concentration | Volume | $ml$ of $HCl$ | $ml$ of $H_{2}O$ |
|---|---|---|---|
| 90% | 100ml | ||
| 80% | 75ml | ||
| 75% | 50ml | ||
| 50% | 50ml | ||
| 30% | 50ml |
| Concentration | Volume | $ml$ of $HCl$ | $ml$ of $H_{2}O$ |
|---|---|---|---|
| 90% | 100ml | $90ml$ | $10ml$ |
| 80% | 75ml | ||
| 75% | 50ml | ||
| 50% | 50ml | ||
| 30% | 50ml |
| Concentration | Volume | $ml$ of $HCl$ | $ml$ of $H_{2}O$ |
|---|---|---|---|
| 90% | 100ml | $90ml$ | $10ml$ |
| 80% | 75ml | $60ml$ | $15ml$ |
| 75% | 50ml | ||
| 50% | 50ml | ||
| 30% | 50ml |
| Concentration | Volume | $ml$ of $HCl$ | $ml$ of $H_{2}O$ |
|---|---|---|---|
| 90% | 100ml | $90ml$ | $10ml$ |
| 80% | 75ml | $60ml$ | $15ml$ |
| 75% | 50ml | $37.5ml$ | $12.5ml$ |
| 50% | 50ml | ||
| 30% | 50ml |
| Concentration | Volume | $ml$ of $HCl$ | $ml$ of $H_{2}O$ |
|---|---|---|---|
| 90% | 100ml | $90ml$ | $10ml$ |
| 80% | 75ml | $60ml$ | $15ml$ |
| 75% | 50ml | $37.5ml$ | $12.5ml$ |
| 50% | 50ml | $25ml$ | $25ml$ |
| 30% | 50ml |
| Concentration | Volume | $ml$ of $HCl$ | $ml$ of $H_{2}O$ |
|---|---|---|---|
| 90% | 100ml | $90ml$ | $10ml$ |
| 80% | 75ml | $60ml$ | $15ml$ |
| 75% | 50ml | $37.5ml$ | $12.5ml$ |
| 50% | 50ml | $25ml$ | $25ml$ |
| 30% | 50ml | $15ml$ | $35ml$ |
Diagrams 🔗
Glue in the diagram and label each beaker with a concentration percentage. Red is acid and blue is water.
