Does the concentration of acid affect the rate of reaction?

 

I will measure how fast the rate of reaction is by measuring the amount of carbon dioxide gas given off using a gas syringe. I will measure this because when calcium carbonate and hydrochloric acid react they produce calcium chloride, water and carbon dioxide:

        

 Using a past experiment not with as many variables I can see that the higher the concentration the faster the rate of reaction.

Due to this evidence I think that the higher the concentration of acid the faster the rate of reaction.

In my experiment I will use the following equipment.

        Gas syringe,

        Measuring cylinder,

        Conical flask,

        Stop clock,

        Marble chips (calcium carbonate),

        Acid,

        Water,

        Goggles

        Clamp and stand.

I will make it a fair test by making sure I weigh out as accurately as possible and by using the same equipment such as the same gas syringe.

I will make the experiment safe by wearing goggles and making sure I follow the rules of safety.

Method

I collected the equipment in the list above and set up the clamp and stand holding the gas syringe just above the conical flask so the bung would fit in and the tube from the gas syringe to the conical flask was horizontal. I then weighed out 3 marble chips with the combined weight of 2.1grams. I then measured out the right amount of acid and water mix shown in the table on page 2. I put the acid and water into the conical flask and then put the marble chips in. As soon as the marble chips were in I put the bung firmly in the conical flask and started the stop clock. Every 15seconds I recorded how much gas there was. I repeated the same routine for all the concentrations just changing the amount of water and acid. Then I repeated all the concentrations one more time and looked for any anomalous results. I had one anomalous result so I had to repeat that experiment again.

I needed to do an extra experiment for the experiment 0.4 because the result came out anomalous. I think that the result may have been anomalous due to a few things such as:

        The surface area of the marble chips were different,

        The acid used might have been slightly diluted,

        The acid may have been by a radiator, which would heat the acid up,

        The gas syringe was faulty.

I have found out that my prediction was correct. When you increase the concentration of acid the rate of reaction increases.

I think that as the concentration of acid increases the rate of reaction increases because there are more actual acid particles to hit the marble chips and react with it. If there were only a few acid particles it can’t react as well with the chips.

My results support this statement and help back up my theory. To draw this conclusion I have used the experiment on page1 using magnesium ribbon and hydrochloric acid.

I think that if I could do the experiment again making improvements I would use the magnesium ribbon experiment because you can control the surface area of the ribbon to more accuracy. Then by using both of my experiments I could compare them and make a very accurate conclusion using different reactants.

I think that the experiment wasn’t very fair because of the variation you could get between the surface area of the chips but still my results show what I thought.

Other experiments I have done previously testing the rate of reaction are the temperature or the acid and the size of the marble chips, these experiments are shown below.

Does the size of the marble chip effect the rate of reaction?

Time                        Large chips                Small chips

15                        4                        14                                

30                        9                        30

45                        16                        44

60                        22                        54

75                        29                        64                

90                        35                        79                

105                        40                        84

120                        47                        98

135                        55                        off scale

150                        56                        off scale

165                        56                        off scale

180                        63                        off scale

Conclusion

The smaller the chips the faster the rate of reaction, this is because there is more surface area on the chips therefore they can react faster.

Does the temperature of the acid effect the rate of reaction?

Time                        20degrees                84degrees

15                        9                        34

30                        16                        54

45                        25                        70

60                        33                        87

75                        40                        off scale

90                        47                        off scale

105                        54                        off scale        

120                        61                        off scale

135                        67                        off scale

150                        73                        off scale

165                        79                        off scale

180                        85                        off scale

Conclusion

We have found out that the temperature affects the rate of reaction. This is because in the hydrochloric acid there is water and hydrogen when heated up the hydrogen gains energy making the hydrogen collide with the marble chips more therefore reacting faster.