When water boils and turns into steam, there are changes in the arrangement of particles and the density - Edexcel - GCSE Physics: Combined Science - Question 6 - 2022 - Paper 1

To find the mass of the lump of iron, we first need to calculate the volume of water displaced by the iron piece, which is given by the rise in water level: 530 cm³ - 490 cm³ = 40 cm³. Now, using the formula for density: $density = \frac{mass}{volume}$, we can rearrange the equation to find mass: $mass = density \times volume = 7.99 \text{ g/cm}^3 \times 40 \text{ cm}^3 = 319.6 \text{ g}$, which rounds to 320 g for the answer to 2 significant figures.

The method used in part (b) cannot determine the mass of the wood because the density of wood (0.82 g/cm³) is less than that of water (1.00 g/cm³). This means that the wood will float, and therefore, it will not displace an equivalent volume of water, leading to an inaccurate measurement.

To determine the specific heat capacity of water, the student should follow this method:

1. Equipment needed: Use a calorimeter, thermometer, low voltage heater, and a stopwatch.
2. Measurements needed: Measure the initial temperature of the water and its volume.
3. Method:
   • Heat the water by using the low voltage heater while constantly stirring to ensure even heating.
   • Record the temperature at regular intervals until a significant temperature change is observed.
   • Use the formula $Q = m \times c \times \Delta T$, where Q is the heat energy supplied, m is the mass of the water, c is the specific heat capacity, and \Delta T is the change in temperature.
   • Calculate the specific heat capacity using the measured data.
   • For accuracy, repeat the experiment several times and calculate the average value.
4. Diagram: A diagram could include labeled equipment, indicating the setup for clarity.