A student wants to find the density of a liquid using a measuring cylinder and a balance. Describe how the student would find the mass and volume of the liquid, and explain how these measurements are used to determine the density.

Cambridge International IGCSE Physics (0625) — 1.4 Density · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

1. Measure the mass of the empty measuring cylinder on a balance.
2. Pour the liquid into the cylinder and weigh the cylinder plus liquid.
3. Subtract the mass of the empty cylinder from the combined mass to obtain the mass of the liquid.
4. Read the volume of the liquid directly from the scale on the measuring cylinder.
5. Calculate the density by dividing the mass of the liquid by its volume (ρ = m/V).

Examiner tips

  • Use the balance to get the mass of the empty cylinder first; this shows understanding of the procedure. Show the subtraction step to find the liquid’s mass. Read the volume accurately from the cylinder’s scale. State the formula ρ = m/V and include units.
  • common_mistakes
  • :
  • Failing to subtract the empty cylinder’s mass, giving the wrong liquid mass. Reading the volume incorrectly or not using the scale. Omitting the density formula or the units in the final answer.

Mark scheme (4 marks)

  1. Mass of empty measuring cylinder is measured using a balance
  2. Pour the liquid into the cylinder and measure the mass of the cylinder plus liquid; subtract the mass of the empty cylinder to find the mass of the liquid
  3. Read the volume of the liquid directly from the scale on the measuring cylinder
  4. Density is calculated by dividing the mass of the liquid by its volume

Key terms in this question

density · mass · volume · measuring cylinder · balance

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