When water boils and turns into steam, there are changes in the arrangement of particles and the density - Edexcel - GCSE Physics - Question 9 - 2022 - Paper 1

We know the density of iron is 7.9 g/cm³, and the change in water level is given by:

$530 cm³ - 490 cm³ = 40 cm³$

Using the formula for density:

$density = \frac{mass}{volume}$

We can rearrange this to find mass:

$mass = density \times volume = 7.9 g/cm³ \times 40 cm³ = 316 g$

Thus, the mass of the lump of iron is 320 g when rounded to two significant figures.

The method cannot be used for wood because wood is less dense than water; it will float on the surface instead of displacing water. Therefore, it will not provide an accurate measure of its volume using water displacement, leading to an incorrect result for its mass.

To determine the specific heat capacity of water, the student should use the following method:

1. Use a low voltage heater to heat a known mass of water in a beaker.
2. Measure the initial temperature of the water using a thermometer.
3. Heat the water for a set period and record the temperature at regular intervals until its temperature stabilizes.
4. Calculate the energy supplied using the heater's power and the time of heating.
5. Use the formula for specific heat capacity: $c = \frac{Q}{m \Delta T}$ where:
   • $c$ is the specific heat capacity,
   • $Q$ is the heat energy supplied,
   • $m$ is the mass of the water,
   • $\Delta T$ is the change in temperature.
6. Ensure to carry out the measurements accurately, and the experiment can be repeated for validation.