In this Investigation, I am going to investigate the effects of concentration on the rates of reaction between magnesium and hydrochloric acid.

Concentration allows us to see how much of a particle is in a given volume, so an increase in concentration leads to an increase in the rate of reaction because there are more particles in a given volume so the particles will be closer together because the particles are closer together therefore they will bump into each other more often with each other. More successful collisions lead to new products being made at a faster rate.

The surface area is increased when the reactants, which is a solid, breaks up into smaller pieces, if you increase the surface area, the reaction will get faster, this is because when a solids surface area is increased (by making it powder) then the atoms/molecules become exposed to other reagents. Therefore, collisions will take place more often between particles of the crushed solids and the particles of the liquid reactants, this results to more successful collisions that lead to the reaction being faster.

A catalyst speeds up the rate of reaction of a chemical reaction, because the catalyst provides another way for the reaction to take place with a lower activation energy. Therefore there will be more successful collisions at any temperature because more of the molecules will have energy greater than the activation energy.

Aim:

to determine if the concentration of hydrochloric acid affects the speed of the reaction of calcium carbonate with hydrochloric acid.

Word equation for this reaction:

Calcium carbonate + Hydrochloric acid → Calcium Chloride + Water + Carbon Dioxide

            CaC03(s)         +           2HCl(aq)       →       CaCl2(aq)           + H20(l) +         C02(g)

                                                                                                                 

                     Reactants                                                    Products

Preliminary method:

The method I used to track the rate of reaction was by using the “Evolution of gas” method, I chose this method because the results were easier to take down and I had the right equipment for this method.

Apparatus: Equipment needed

• Goggles
• Lab coat
• Delivery tube
• Rubber bung/conical flask
• Two measuring cylinders
• Stop watch
• Weighing scale
• Marble Chips
• Water bath

Method:

1. I collected all my equipment that I need for my experiment
2. I measured 25ml of hydrochloric acid
3. I weighed 1.5g of Calcium Carbonate (chips)
4. I poured the acid into a conical flask
5. I put the Calcium Carbonate (chips) into the conical flask
6. I inserted the rubber bung into the top of the conical flask
7. I took down the reading every ten seconds for three minutes

Safety precautions:

During this investigation safety will be important. To ensure safety, the method must be correct. Goggle and gloves must be worn at all times during the experiment, because if there is a splash back, hydrochloric acid is very irritant and will cause problems when in contact with the eye, if it comes into contact with the hand it will cause itchiness and may become a rash.

Fair testing:

The variables needed to be kept the same in order to keep this investigation a fair test:

• The volume of Hydrochloric acid
• The temperature of water
• The surface area of the Calcium Carbonate (chips)
• The mass of Calcium Carbonate

Analysis & Conclusion:

My results show that as the concentration increased, the volume of which carbon dioxide was produced increased rapidly. When the Concentration was 0.5M, at 50 seconds, 15cm3 of volume was produced, whereas when the Concentration was 1.0M, at 50 seconds it was 55cm3, and when the Concentration was 1.5M, at 50 seconds it was 75cm3. When the concentration was 2.0M, at 50 seconds the volume of carbon dioxide produced decreased, at 50 seconds, the volume was 53cm3. The results went as I expected except at 2.0M when the volume of carbon dioxide produced decreased when I expected it to increase.

Evaluation:

I think that the anomalous results may have arisen by inaccuracies. Calcium Carbonate was not measured out to the exact amount need or not enough acid.

Also, the conical might have been shaken during the experiment which has an effect on the reading. Time intervals were to long, for example 60 seconds interval. Rinsing out the Conical flask properly after each experiment is vital as chemicals from the previous experiment may have an effect on the reading/result of the experiment.