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Edexcel IGCSE Chemistry 2.10 testing oxygen percentage

Practise oxygen-percentage questions by calculating volume changes, explaining water rise and suggesting accuracy improvements.

Syllabus
First assessment 2019
Course
Chemistry 4CH1

Exam points

  • Calculate oxygen percentage from initial and final gas volumes or column heights.
  • Explain water rise or syringe movement by oxygen reacting and gas volume decreasing.
  • Suggest improvements such as repeating, measuring more precisely or leaving enough reaction time.

2.10 Testing oxygen percentage question 1

[Maximum number: 9]

A student uses the reaction between iron and oxygen to find the percentage of oxygen in air.

The diagram shows the apparatus the student uses.

Figure for Question 2.10 Testing oxygen percentage question 1 — Edexcel IGCSE Chemistry

Question (a)

(a)

State why the iron powder needs to be wet.

[ 1 ]

Question (b)

(b)

State the colour of the compound formed in the reaction between iron and oxygen.

[ 1 ]

Question (c)

(c)

Explain the advantage of using iron powder rather than pieces of iron.

[ 2 ]

Question (d)

(d)

The syringe in the diagram shows the reading at the end of the experiment.

Complete table 1 to show the readings on the syringe.
Give both values to the nearest 1 cm3.

table 1

table 1

[ 2 ]

Question (e)

(e)

The student repeats the experiment and obtains a different set of results.

Table 2 shows these results.

Use the results from table 2 to calculate the percentage by volume of oxygen in the air.

percentage by volume of oxygen in air = ................................ %

Table 2

Table 2

[ 3 ]
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