A cylinder fitted with a freely moving piston contains 12.0 g of a pure substance. The cylinder is sealed so that no substance can enter or leave.
The substance is heated and passes through stages P, Q and R.
| Stage | Observation | Volume in cm3\mathrm{cm^3}cm3 |
|---|---|---|
| P | The substance keeps its own shape. | 8.0 |
| Q | The substance takes the shape of the bottom of the cylinder but does not fill all the space below the piston. | 8.6 |
| R | The substance spreads out to fill all the space below the piston. | 6.0 × 103 |
Explain why, at stage Q, the substance takes the shape of the cylinder but has a volume only slightly greater than at stage P.
Calculate the density of the substance at stage R in kg/m3\mathrm{kg/m^3}kg/m3.
The substance can also change directly from stage P to stage R without passing through stage Q.
Use the observations and volume data to explain how the separation and movement of the particles change during this direct change.
Explain, in terms of particles, why heating the substance from stage P to stage R does not change its total mass.
87 exam-style questions on Edexcel GCSE Physics 14.1 Density and states of matter, covering 14.1.1 Kinetic theory and states of matter, 14.1.2 Density, and 14.1.3 Density and changes of state. Each one has a worked solution and a mark scheme showing where the marks go.