Quick answer: The mole is the chemist's counting unit: one mole contains 6.02 × 10²³ particles, the Avogadro constant. This Chemistry 9-10 test on mole calculations has 8 questions worth 20 marks, to do in 45 minutes: Avogadro constant, aluminium nitrate and mass of copper oxide. The mark scheme is on a separate page; free printable PDF.
This test lasts 45 minutes and carries 20 marks. A periodic table of relative atomic masses is provided in each question, and the Avogadro constant is 6.02 × 10²³ per mole. Show your working clearly, because marks are given for the method as well as the answer.
Level: Chemistry grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: HS-PS1-7, GCSE C3
Question 1 Avogadro constant (2 marks)
State the value of the Avogadro constant and say what it represents. (2 marks)Question 2 Aluminium nitrate (3 marks)
Ar values: Al 27, N 14, O 16.- Calculate the relative formula mass of Al(NO₃)₃. (2 marks)
- Calculate the amount in 21.3 g of the compound. (1 mark)
Question 3 Mass of copper oxide (3 marks)
Calculate the mass of 0.40 mol of copper(II) oxide, CuO. Ar values: Cu 63.5, O 16. (3 marks)Question 4 Molecules in water (3 marks)
Calculate the number of molecules in 3.6 g of water. Ar values: H 1, O 16. (3 marks)Question 5 Oxygen error (2 marks)
A student calculates the amount in 8.0 g of oxygen gas as 8.0 ÷ 16 = 0.50 mol. Explain the mistake and give the correct answer. (2 marks)Question 6 Moles in 10 g (3 marks)
The chart shows the amount in moles in 10.0 g of four substances.- State which sample contains the most molecules or formula units. (1 mark)
- Explain why. (1 mark)
- Calculate the number of molecules in the water sample. (1 mark)
Question 7 Nitrogen in fertiliser (2 marks)
Calculate the percentage by mass of nitrogen in ammonium nitrate, NH₄NO₃. Ar values: N 14, H 1, O 16. (2 marks)Question 8 Chloride ions (2 marks)
Calculate the amount of chloride ions in 0.30 mol of calcium chloride, CaCl₂. (2 marks)
