When calcium turnings are heated in a crucible, they react with oxygen in the air to form calcium oxide, CaO\text{CaO}CaO.
A class of students investigated the relationship between the mass of calcium heated and the mass of calcium oxide formed.
Each student was given a different mass of clean calcium turnings to heat. The students used the following method:
Why is it necessary to lift the lid from time to time while heating?
Why is it necessary to repeat the heating until two consecutive masses are the same?
Show how the mass of calcium oxide formed can be calculated from the readings obtained.
The results of each student's experiment are given in the table below:
| Mass of calcium (g) | Mass of calcium oxide (g) |
|---|---|
| 0.50 | 0.70 |
| 1.00 | 1.40 |
| 1.50 | 2.50 |
| 2.00 | 2.80 |
| 2.50 | 3.50 |
| 3.00 | 4.20 |
Identify the anomalous result by stating the mass of calcium for which it occurred.
Use the consistent results from the table to calculate the mass of calcium oxide formed when 1.65 g1.65\text{ g}1.65 g of calcium is completely reacted.
80 exam-style questions on Edexcel IGCSE Chemistry Chemical formulae, equations and calculations. Each one has a worked solution and a mark scheme showing where the marks go.