A sealed container holds 24.0 g of solid substance X. The container is warmed until all of X has changed directly into a gas. The container stays sealed throughout.
State whether the particles of X before and after the change are the same or different.
A student uses M and O to represent two different types of atom. The table describes two particle models of a change.
| Model | Before the change | After the change |
|---|---|---|
| P | four particles, each containing one M atom and one O atom, packed closely together | the same four particles, each containing one M atom and one O atom, far apart |
| Q | four M atoms and four O atoms, all separate | four particles, each containing one M atom and one O atom |
Which model shows a chemical change? Write P or Q.
The mass of X is measured before and after the change.
Complete the table by writing the mass of X after the change.
| Stage | Mass of X |
|---|---|
| before warming | 24.0 g |
| after all of X has changed into a gas | ______ |
93 exam-style questions on OCR GCSE Chemistry 1.1 The particle model, covering 1.1.1 The particle model and changes of state and 1.1.2 Limitations of the particle model. Each one has a worked solution and a mark scheme showing where the marks go.