# Investigation: How does channging the concentration of a substance affect the rate of reaction?

A chemical reaction is the process by which atoms or groups of atoms are redistributed, resulting in a change in the molecular composition of substances.

The reaction rate is how quickly a reaction occurs. I will be using the reaction rate during my investigation to see how the concentration of acid effects the reaction rate. To do this I will be using the following reaction

Hydrochloric + Calcium Ü Calcium + Carbon + Water

Acid Carbonate Chloride Dioxide

powder

2HCl + CaCO3 Ü CaCl2 + CO2 + H2O

I will be using these substances because I know from my research and previous experiment that these two substances react well together. So, I will be able to have quick and efficient experiments.

I will be using the following equipment and setting the equipment up as shown in the diagram.

2. Gas Syringe

3. Rubber plug

4. Stop Clock

5. Top Pan Balance

6. Heat Proof mat

7. Clamp and Boss

8. Clamp Stand

I will be testing to see how the concentration of the hydrochloric acid effects the reaction rate. I will be able to see this by measuring the gas using the gas syringe. As carbon dioxide is released during the experiment, I will measure how much carbon dioxide will be produced in certain amounts of time. I will then draw a graph to show how much carbon dioxide had been produced in several time intervals. I will then take the gradient at one point in the graph where each line is straight.

This will show me the reaction rate of each experiment. I will use five different concentrations of acid. Below are the different concentrations I will be using.

Quantity of HCl (ml) Quantity of H20 (ml)

50 0

45 5

40 10

35 15

30 20

25 25

From this information, I can work out what molar, the acid is. I will do this by using a special formula, the formula is:

Volume of acid X 2

Total volume of solution

Dividing the volume of acid by the volume of gas will show how much of the solution is...