To find out how concentration affects the rate of reaction between Calcium Carbonate and Hydrochloric Acid

Apparatus: Conical Flask, bung, large and small measuring cylinders, bowl/water bath, rubber tubing, scales, stop watch, Calcium Carbonate chips and Hydrochloric Acid.

Scientific equation: 2HCl (aq) + CaCO3 (S) –> CaCl2 (aq) + H2O (l) + CO2 (g)


Safety Precautions:

* Always wear goggles

* Ware an apron

* Wash hands after handling calcium chips

* Be careful with the acid

* Stick to written amounts of acid and calcium

Variables: Input Output

* Concentration Amount of gas

* Mixed or not How long it took to collect ‘x’ amount

* Amount

Practical Method: Set up the apparatus as shown in the diagram. Making sure the inverted measuring cylinder is full of water. Place end of rubber tubing inside the cylinder. Put ‘x’ amount of acid and water solution into the conical flask. Place in ‘x’ weight of Calcium Carbonate chips then start the stop watch as soon as the bung is replaced in the conical flask.

Time how long it takes to collect 50ml3 of gas. Now change the concentration of the acid in the solution and do the same two more times. When this has been done change the weight of calcium chips and perform experiment three times with that weight. Then change weight again and do experiment a further three times.

Theory diagram:

The higher the concentration of acid there is, the more likely the chance of a reaction there is. The more reactions means more gas is produced and at a faster rate.

Prediction: My prediction is, the more acid concentrated solution it is the shorter the time it will take to fill the measuring cylinder to 50ml3 of gas, so if there is 60% water and 40% acid it will fill slower than a solution of 20% water and 80% acid.


Concentration %






3.43 minutes

3.48 minutes

3.29 minutes

3.40 minutes


2.30 minutes

2.43 minutes

2.32 minutes

2.35 minutes


2.08 minutes

2.04 minutes

2.11 minutes

2.08 minutes


1.23 minutes

1.51 minutes

1.38 minutes

1.37 minutes


1.09 minutes

1.22 minutes

1.23 minutes

1.18 minutes

Conclusion: The time gets shorter as the concentration of acid gets greater; slowly the time decreases as the acid grows form 60% to 100%. This confirms my prediction to be correct.