11.2 Synoptic Data Handling & Graphical Skills

A student titrated hydrochloric acid solution against 50.0 cm³ of 0.950 mol dm^-3 sodium hydroxide solution to determine is concentration.

After each addition of acid the temperature was measured to the nearest 0.5 ^oC and recorded and plotted on a graph:

What should the labels be on each axis?

[1]

Use the graph to:

Estimate the initial temperature of the solution.

Determine the maximum temperature reached in the experiment

Use the values obtained in part b) to determine the temperature change and percentage uncertainty in the calculated value.

[2]

Determine the concentration of the acid used in the experiment.

[1]

A student investigated the diffusion of ammonia and hydrogen chloride gases in a 1.00 m glass tube. She placed cotton wool plugs containing concentrated ammonia and hydrochloric acid at either end of the tube and sealed the ends with stoppers. 

Where the two gases meet a white smoke ring of ammonium chloride, NH₄Cl, appears. The student recorded the time taken for the white smoke to appear and the distance travelled by each gas.

	1st trial	2nd trial	3rd trial
Total time elapsed /s	126	114	163
Distance travelled by NH3 (g) / cm	72	68	75
Distance travelled by HCl (g) / cm	28	32	25

The rate of diffusion of a gas is proportional to the square root of the mass of its particles.

Calculate the mean rate of diffusion of ammonia and hydrogen chloride, expressing your answer to an appropriate number of significant figures.

[3]

The rate of diffusion of a gas is proportional to the square root of its mass.

When two gases, A and B, are compared the relative rates of diffusion are: 

Determine the relative rate of diffusion of the ammonia and hydrogen chloride from their molar masses and from part a).

Comment on your result.

[3]

Determine the percentage error in the experiment.

The student cleans and dries the glass tube between each run of the experiment. If the glass tube is not completely dry, state what type of error can occur and what its impact on the results would be.

[2]

The graph below shows measurements of pressure and volume for a sample of air at constant temperature.

Deduce the relationship between pressure and volume in the sample of air.

[1]

Given the average molar mass of air is 28.97 g mol^-1, find the number of moles of air used in the experiment using the values at point X.

[4]

Determine the percentage uncertainty in the measure data at point, X.