## 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 successful collisions overall
• It does not increase the probability of successful collisions

## Dilutions

• To change the concentration we must dilute one of our reactants.
• Question: What do we dilute raro with (we use the same in chemistry)?
• Answer: Water! $H_{2}O$

### Dilutions Explained

• In Year 11 we will do dilutions in percentages. For example, 90% $HCl$, 80% $HCl$ or 30% $HCl$
• For $10ml$ of 80% $HCl$ this means 80% of the $10ml$ is $HCl$ and 20% is water!
• Calculate the $ml$ of acid and water for the above solution ^

$$\text{Volume of Acid} = \frac{percentage}{100} \times \text{total volume}$$

### Task: Calculate the $HCl$ and $H_{2}O$ for each solution

$$\text{Volume of Acid} = \frac{percentage}{100} \times \text{total volume}$$

ConcentrationVolume$ml$ of $HCl$$ml of H_{2}O 90%100ml 80%75ml 75%50ml 50%50ml 30%50ml ConcentrationVolumeml of HCl$$ml$ of $H_{2}O$
90%100ml$90ml$$10ml 80%75ml 75%50ml 50%50ml 30%50ml ConcentrationVolumeml of HCl$$ml$ of $H_{2}O$
90%100ml$90ml$$10ml 80%75ml60ml$$15ml$
75%50ml
50%50ml
30%50ml

ConcentrationVolume$ml$ of $HCl$$ml of H_{2}O 90%100ml90ml$$10ml$
80%75ml$60ml$$15ml 75%50ml37.5ml$$12.5ml$
50%50ml
30%50ml

ConcentrationVolume$ml$ of $HCl$$ml of H_{2}O 90%100ml90ml$$10ml$
80%75ml$60ml$$15ml 75%50ml37.5ml$$12.5ml$
50%50ml$25ml$$25ml 30%50ml ConcentrationVolumeml of HCl$$ml$ of $H_{2}O$
90%100ml$90ml$$10ml 80%75ml60ml$$15ml$
75%50ml$37.5ml$$12.5ml 50%50ml25ml$$25ml$
30%50ml$15ml$$35ml$

### Diagrams

Drawing a diagram is a very good way to visually show the amount of water and acid/base in your dilutions. Perhaps this could go in your method!