Investigation into the effect of concentration on the rate of reaction between calcium carbonate and hydrochloric acid
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Investigation into the effect of concentration on the rate of reaction between calcium carbonate and hydrochloric acid. Introduction Equation: Calcium carbonate + hydrochloric acid carbon dioxide + water + calcium chloride CaCO + HCl CO + H O + CaCl During this reaction Carbon dioxide is formed. We measured the rate of reaction by collecting the Carbon dioxide in a gas syringe and timing how long it takes to collect 30cm of gas in the gas syringe. Variables that Affect the Rate of Reaction: -Concentration- if there is a higher concentration of acid then there will be a faster rate of reaction because there will be more reactant particles per unit volume, so there will therefore be more successful collisions occurring. -Temperature- if the temperature is higher there will be a faster reaction rate. This is because the average kinetic energy of the particles will be higher and therefore the collisions will have more energy so successful collisions will increase. -Size of chips (surface area)- If the marble chips are larger then there will be more surface area exposed and so there will be a faster reaction rate due to more successful collisions occurring. -Catalyst- A catalyst lowers the energy needed for successful collisions. So the reaction rate will therefore be faster.
If the concentration is higher then there will be more particles per unit volume. Observations The only possible anomaly that I can see from the preliminary results table is the result for time taken to collect 30cm of gas, and the concentration of acid being 12. Results for actual experiment. Concentration of solution moles dm 3 Volume of Acid moles dm 3 (cm ) Volume of Water (cm ) Time taken to collect 30cm of gas (s) (1st test) Time taken to collect 30cm of gas (s) (2nd test) Time taken to collect 30cm of gas (s) (3rd test) Average time taken to collect 30cm of gas (s) 2.0 20 0 6 7 8 07.00 1.8 18 2 9 9 10 09.33 1.6 16 4 11 10 10 10.33 1.4 14 6 13 12 11 12.00 1.2 12 8 15 10 14 13.00 1.0 10 10 18 17 19 18.00 Rate of reaction: 1/time Concentration of solution moles dm 3 Rate of reaction s 1 2.0 0.14 1.8 0.11 1.6 0.10 1.4 0.08 1.2 0.08 1.0 0.06 Analysing I have found from my results that my prediction was correct and that as the concentration of acid increases, the rate of reaction increases, and as the concentration of acid decreases, the rate of reaction decreases.
There are still some factors that could cause an anomaly using this method, for example, human error. Reactions could be delayed when starting the stop clock. Other anomalies could have been because the gas syringe could have stuck, also, even though we did our best to keep the chips the same size, we could not guarantee they would be the correct size. This would alter the rate of reaction to make it faster or slower. We could possibly have ruled this out by getting a machine to cut the marble chips into precise sizes, but this would take a long time and would be impractical, and is therefore beyond our control. The temperature could also have changed, even though we attempted to keep it the same, although we did not measure the temperature with a thermometer. This was also beyond our control as we did not have the equipment to keep the temperature at a constant level. Another problem that we found was that one of the boiling tubes broke during the experiment and a small bit of glass had fallen out of the bottom of it. This was faulty equipment. Other than these possible reasons I can conclude that the experiment as fairly and accurately as possible with the equipment and conditions that we were operating in, and that the results are valid. ?? ?? ?? ?? Charlotte Bell 10A
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