What factorsaffect the rate of reaction between limestone and acid?

2HCL+ CaCO3         Co2+ CaCL2 + H2O

Theory

In any given chemical reaction we can measure how fast the reaction is progressing by either measuring the disappearance of a reactant for example calcium carbonate (limestone) or the appearance of a product for example carbon dioxide  in a given amount of time.  It is essential to measure the time in which the product is being given off to find out the reaction time or rate of reaction for example volume of gas in cm3 in seconds (time).  The amount of product measured at intervals of time in seconds will show us how the rate of reaction changes within each experiment with a given molar concentration of acid.  As the reaction takes place the amount of calcium carbonate reacts with a given concentration of acid and gets less in proportion to the amount of product carbon dioxide released. In the initial stages of the experiment the acid  at lower concentration will release small amounts of carbon dioxide , however it is expected that as the concentration increases the reaction will not only speed up but will release the gas more optimally.  Finally a point will be reached that beyond an optimum concentration of acid for 1gram of limestone; there will be no further increase in the volume of gas released. The experiment would be limited by amount of solute present.  All the measurements can only be made accurately by plotting the measurements of the gas given off in cm3 against time in seconds.  The will enable us to measure several things chief being (1) how fast or slow the reaction is (2) the progression of the speed of the reaction with increase in the concentration of the acid,(3)  to analyse the graphs , i.e., at what time the rate of reaction is highest,  if the rate of reaction falls with time,  if the reaction stops.

Prediction

In this experiment we are going to measure the rate of reaction between hydrochloric acid and calcium carbonate (lime stone).  Calcium carbonate + hydrochloric acid

         Calcium chloride + water + carbon dioxide. We are going to measure the rate of reaction by the amount of carbon dioxide gas given off in seconds with increasing concentrations of acid to a given standard mass of lime stone (1.0g). I predict that with in increasing concentrations of acid there will be a gradual increase in the rate of reaction till an optimal reaction rate is reached. It is expected that at a lower molar concentrations the amount of carbon dioxide gas given off will be less in a given amount of time (seconds) than at higher molar concentrations of acid.

Plan.

In my experiment I am investigating and measuring how much gas is given off in a certain amount of acid. We used the following apparatus in our experiment:-

• One clamp stand
• One basin of water
• Dilute hydrochloric acid
• One measuring cylinder
• Lime stone
• Test tube

Here is a diagram of our experiment.

Once we have collected all the equipment needed to carry out the experiment, we needed to first of all put it together and set the apparatus up. We did this by first of all taking a plastic container and filling it with water, then putting it underneath the clamp stand. Once we had done this, we then took a measuring cylinder and filled it to the brim with water.  We had to refrain from letting any water out of the cylinder because this could ruin the experiment. So what we did was I put my hand over the cylinder and very carefully turned it upside down, then placed it into the plastic container. Then once I had done this, I then held the cylinder in place and clamped it to the clamp stand.

 Now we had the main section of the apparatus set up, so what we needed to do was to choose how heavy our limestone would be, to go into our test tube. Since we were going to repeat the experiment several times, we had come to a decision to choose 1.0g of lime stone in the test tube. We carefully measured the lime stone on some electronic scales and once we were happy that we had enough lime stone that came to the weight of 1.0g we then placed it into the test tube. We also had to place a cork at the top of the test tube just in case any hydrochloric acid were to spurt out of the tube. So after we had done this, we then had to get the hydrochloric acid ready but since we were repeating the experiment with different volumes of acid we started with a low molar and increased the amount of acid each experiment, we started off with 0.2 molar and increased up to 1.0 molar.  We had to dilute the acid because otherwise the reaction would be far too violent. So we got a syringe and diluted the acid with water. Once we had done this we were almost ready to start the experiment. We just had to do one more step to complete and that was to get some rubber piping and plug it to the end of the syringe, so that we can transfer the acid from the syringe to the test tube with out spilling the acid everywhere. So now that we had all the apparatus set up we were ready to begin the experiment.

Step 1

The first step of carrying out this experiment was to first of all squeeze the acid out from the syringe into the test tube. From there we then quickly removed the rubber piping from the syringe and then directed the piping from the test tube up into the measuring cylinder. From this point the o2 from the test tube was going up into the measuring cylinder.

Step 2

 The second step to this experiment was then to take a stop watch and start timing, every 15 seconds we would record how much the water went down on the measuring cylinder e.g. at the first 15 seconds the volume of gas (cm3) was 13.2 and so we kept timing every 15 seconds until the gas had stopped coming out if the test tube or the volume of gas no longer increased or decreased.

Step 3

Once we had completed the first experiment we then repeated the experiment 4 more times but with different amounts of acid for example we started off with 0.2 molar then 0.4, 0.6, 0.8 and then finally 1.0 molar of acid.

What is a moler?

A mole is a measure of quantity in chemistry. Just like a ream of paper that contains 500 sheets, a mole of a substance contains ox1023atoms.

I.E

        A3

                                        A4

                                                                    A5

                                                                        

1 ream= 500 sheets                      1 ream= 500 sheets        1 ream= 500 sheets

Here are our table of results

Analysis of results:

Conclusion

The analysis of my results as plotted on the graphs show that the theory and prediction made at the beginning of the experiment are valid.  The graphs are used to measure the rate of reaction and the volume of carbon dioxide given off in a given amount of time.  With progressively increasing the concentration of acid the volume of carbon dioxide released increased.  The plots also revealed that at first there is a gradual increase of carbon dioxide given off (linear part of the graph) which later plateaus out.  This is more evident in the lower concentrations of acid than at the higher concentration, where this effect cannot be seen as the reaction speed increases and stops.

The rate of reaction can be calculated: by the volume of gas divide by the time taken acid concentration 0.2 molar. The slop of y 1

Rate of reaction = increase in volume of gas time taken.