Title: Factors affecting reaction ratesProcedure A: Effect of ConcentrationAim: To investigate how the concentration of a reactant affects the rate of reaction.
Hypothesis: The more concentrated the reactant, the faster the rate of reaction.
Materials: 2M hydrochloric acid solution, magnesium wire, distilled water, 4 test-tubes, measuringcylinder.
Procedure:1)10mL 2M hydrochloric acid solution is poured into a test-tube using a measuring cylinder.
2)A 3cm length of magnesium wire is added to the acid, and the stopwatch is started simultaneously. The time it takes for the magnesium to disappear into solution is recorded. This time is recorded in the results table.
3)The test-tube is rinsed thoroughly and step 2 is repeated using 8mL acid mixed with 2mL water.
4)This is repeated for each acid-water mixture, as shown in Table 1.
Results:Table 1Volume of HCl(ml)Volume of water (mL)Time taken (s)100418252736664120Calculations:Table 2Volume of HCl(ml)Volume of water (mL)Concentration (mol/L)1002821.6731.4641.2Discussions:The reaction between magnesium and hydrochloric acid:Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)Increasing the concentration of the hydrochloric acid will increase its solubility.
The higher concentration of acid means there are more reactants per molecule, making the reaction of the magnesium more effective.
Sources of error in this experiment:The dilution process of the hydrochloric acid is very crude. This means that the reaction rate will be affected, but not by a lot.
The size of the magnesium wire is not equal. This will also affect the consistency of the results, but again, not by a lot.
The recording of the time may not be absolutely accurate.
The experiment could be improved by reducing the sources of error i.e. handling the equipment as accurately as possible.
Conclusion: The higher the concentration of the reactant, the higher the rate of reaction.