Aim: to investigate the effects of temperature and concentration on the rate of reaction.

Materials: All the equipment are listed in page 47 of year 9 chemistry booklet

Method: Part One. 1. Using a marker pen, label four beakers/ test tubes “Thio” 2. Using a graduated cylinder, measure 10ml of sodium thiosulfate solution and pour into the test tubes 3. Using marker pen, label four test tubes “HCL” 4. Place 5mL of hydrochloric acid into these test tubes 5. Immerse all 8 test tubes in 450mL beaker (water bath) of water at 5 degrees 6. Set up a 100mL beaker on paper marked with a large cross 7. After about 3 minutes, take one test tube of each solution. Pour them into a 100mL beaker and start the stop watch. 8. Stop the time when the cross disappears. Record the time taken in the results table 9. Repeat steps 2-7 at temperatures at about 20, 40, 55 and 70 degrees.

Method: Part Two. 1. Label four beakers and fill with the following solutions:

Sodium Thiosulfate Solution | Deionized Water | Beaker 1 | 50 mL | 0 mL | Beaker 2 | 40 mL | 10 mL | Beaker 3 | 30 mL | 20 mL | Beaker 4 | 20 mL | 30 mL | Beaker 5 | 10 mL | 40 mL | 2. Put Beaker 1 on the sheet of paper marked with a black cross 3. Add 5 mL of hydrochloric acid and stir the acid into the solution and start the stopwatch 4. Stop the stopwatch when the cross in not longer visible through the beaker 5. Record the time in the table. 6. Repeat steps 2-5 for beakers, 2,3,4 and 5

Results: Temperature ( °c ) | Time (seconds) | 5 | 83.4 | 20 | 54.69 | 40 | 32 | 55 | 20.63 | 70 | 9.75 | Part One: Part One:

Part Two: Part Two:

Thiosulfate Volume (mL) | Deionized water (mL) | Time (seconds) | 50 mL | 0 mL | 34.1 | 40 mL | 10 mL | 40.5 | 30 mL | 20 mL | 62.4 | 20 mL | 30 mL | 88.8 | 10 mL | 40 mL | 243 |

Part One: Graph
Time (seconds)

Time (seconds)

Temperature °c

Temperature °c

Part Two: Graph
Time (seconds)

Time (seconds)

Thiosulfate concentration (mL)

Thiosulfate concentration (mL)

Discussion:
In this practical, it was observed that temperature and the concentration of the reactants affect the rate of reaction. Through the collected data and graphs shown above, (part one) a clear link has been established between the temperature and the rate of which the reaction proceeded. The higher the temperature the faster the reaction will occur. This is so, because as particles heat up, as the rise in temperature they tend to become more active and move/ vibrate faster, the higher the temperature the faster they move, thus the faster they move the more “collisions” per second, thus heat determines the rate of reaction. At cooler temperatures, particles slow down and lose speed, decreasing the amount of collisions per second, thus decreasing the rate of reaction. With higher temperatures, the sodium thiosulfate particles collided faster with the hydrochloric acid particles; and with cooler temperatures, particles took longer to collide with the hydrochloric acid.

The second experiment, which regarded the concentration of the reactants, it was observed through the results that higher concentrations of sodium thiosulfate resulted in faster reactions. This can be explained as follows: Increasing the concentration of the reactants (sodium Thiosulfate and hydrochloric acid) will increase the frequency of collisions between the reactants, thus increasing the rate of reaction, however; if the solution is diluted, the particles need to travel more to collide with each other, thus decreasing the rate of reactions. With higher concentrated