# Experiment: Determining how concentration affects rates of reaction

////Experiment: Determining how concentration affects rates of reaction

## Experiment: Determining how concentration affects rates of reaction

The rate of reaction increases with an increase in concentration

### ZIMSEC O Level Combined Science Notes: Experiment: Determining how concentration affects rates of reaction

Aim: To find the effects of concentration on the rate of reaction using hydrochloric acid and sodium thiosulphate

Materials: 250cm3 beaker, measuring cylinder, stop clock/a watch/phone with a stop watch app, sheet of white paper, dilute hydrochloric acid, sodium thiosulphate

Method

1. Use a measuring cylinder to measure and pour 50cm sodium thiosulphate into a clean beaker
2. Draw an on the sheet of paper
3. Place the jar over the X on the paper
4. Add 5cm3  of dilute Hydrochloric acid to the solution in the jar at the same time take note of the time
5. Look down vertically through the solution at the at the bottom of the jar
6. Note the time it takes for the to “disappear” i.e the solution becomes so cloudy it is impossible to view the through the solution
7. Rinse the beaker
8. Place 40cm of sodium thiosulphate into a measuring cylinder and top it up to 50cm using distilled water
9. Pour into a clean beaker
10. Add of 5cm acid  and note the time it takes for the to disappear
11. Rinse the beaker again
12. Repeat the test using 30cm, 20cm , and 10cm topping up to 50cm with water each time. Take note of the time it takes for the to disappear
13. Tabulate the results
14. Plot the results on a graph with the amount of sodium thiosulphate on the y-axis and time it takes for the to dissappear on the x-axis

Results and observations

Rate of reaction and concentration. Image credit bbc.com

• Diluting the sodium thiosulphate decrease its concentration
• Each time the concentration is reduced the takes longer to disappear

Conclusion

• The higher the concentration of a solution the faster the rate of the reaction
• All things being equal increasing the concentration of  one or more of the reagents results in an increase to the rate of reaction

To access more topics go to the Combined Science Notes page.

By |2017-01-17T11:13:48+00:00April 18th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|1 Comment

### About the Author: Garikai Dzoma

He holds an Honours in Accountancy degree from the University of Zimbabwe. He is passionate about technology and its practical application in today's world.