Edexcel IGCSE Chemistry 6 Mathematical Skills Questions

A student investigates the effect of temperature on the rate of reaction between two solutions, A and B . When the reaction occurs, the mixture turns from colourless to blue.

This is the student's method.
- pour $25 \mathrm{~cm}^{3}$ of solution A into a conical flask
- add solution B and measure the temperature of the mixture
- record the time taken for the mixture to turn blue

The student repeats this method at different temperatures.

This question is about displacement reactions.

A student uses this method to investigate what happens when excess metal is added to a solution of copper(II) sulfate.
- pour some copper(II) sulfate solution into a polystyrene cup and record the temperature
- add excess metal W to the polystyrene cup and stir the mixture
- record the maximum temperature reached
- calculate the temperature increase of the solution

The student repeats the method for metals X, Y and Z.
For each metal, the student records three sets of results.

The table shows the student's results.

Calculate the mean temperature increase for metal Y.

Give your answer to two significant figures.
mean temperature increase = ${ }^{\circ} \mathrm{C}$

A student uses this apparatus to investigate the rate of reaction between dilute sulfuric acid and an excess of small pieces of zinc.

This is the student's method.
Step 1 use $50 \mathrm{~cm}^{3}$ of dilute sulfuric acid
Step 2 add approximately 5 g of small zinc pieces to the sulfuric acid
Step 3 quickly connect the gas syringe
Step 4 record the reading on the gas syringe every 30 seconds until the reaction stops

The graph shows the volume of gas collected in the syringe during the experiment.

A tangent to the curve has been drawn at a time of 80 s .

Use the tangent to calculate the rate of reaction at 80 s .
Show your working on the graph.
Give the unit.
rate of reaction = unit