Mandatory Student Experiment No. 14B

Question 1

What is studied in this experiment?

Answer 1

The effect of temperature on reaction rate using sodium thiosulfate solution and hydrochloric acid

Question 2

Describe the 9 steps to this experiment

Answer 2

1. A conical flask is placed on a sheet of white paper marked with a cross
2. 100 cm cubed of 0.05 cm cubed of sodium thiosulfate solution is added to the conical flask at room temperature
3. 5 cm cubed of 3 M HCL is added to sodium thiosulfate solution
4. The conical flask is swirled and a stop clock is started
5. The exact temperature of the contents of the flask is recorded
6. The time in seconds taken for the cross to disappear is recorded
7. The rate as the inverse of the time (1/time) is calculated
8. The equipment is rinsed
9. The experiment is repeated at different temperatures i.e. the sodium thiosulfate is heated to 30, 40, 50 and 60 degrees Celsius using a hot plate before adding the HCL

Question 3

What is the conical flask placed on in this experiment?

Answer 3

A white sheet marked with a cross

Question 4

How much 0.05 M sodium thiosulfate solution is added to the conical flask?

Answer 4

100 cm cubed

Question 5

What M of sodium thiosulfate solution is used?

Answer 5

0.05 M

Question 6

What M of HCL is used?

Answer 6

3 M

Question 7

How much 3 M HCL is added to the sodium thiosulfate solution?

Answer 7

5 cm cubed

Question 8

What is done once the HCL has been added to the sodium thiosulfate solution?

Answer 8

The conical flask is swirled
The flask is placed on the sheet marked with a cross
A stop clock is started

Question 9

When is the exact temperature recorded?

Answer 9

After the acid has been added to the sodium thiosulfate solution

Question 10

What is recorded once the sodium thiosulfate solution has been combined with the HCL?

Answer 10

The exact temperature is recorded

Question 11

When is the reaction said to be completed?

Answer 11

When the cross can no longer be seen through the solution

Question 12

When is the stop clock stopped?

Answer 12

When the solution has become milky/ colour change form colourless to creamy yellow

Question 13

What is recorded after the reaction has stopped?

Answer 13

The rate of the reaction as an inverse of time (1/time)

Question 14

What is done before the experiment is repeated?

Answer 14

The equipment is rinsed

Question 15

At what temperatures is the experiment repeated?

Answer 15

30, 40, 50 and 60 degrees Celsius

Question 16

When a graph of the rate of the reaction is plotted against the temperature, what type of graph is observed?

Answer 16

Unlike the graph used to plot the rate of reaction against concentration of sodium thiosulfate solution in M/L the rate of reaction is not directly proportional to the temperature and it is therefore not a straight line graph