(b) Density and pressure

5.03 know and use the relationship between density, mass and volume:

Units of density depend on units used for mass and volume:

E.g. mass in [g] and volume in [cm3] gives density in [g/cm3], however mass in [kg] and volume in [m3] gives density in [kg/m3].

5.04 practical: investigate density using direct measurements of mass and volume

  • The density of an object can be found by measuring the mass and volume and applying the formula above to calculate the density.
  • For a regular object use a ruler to measure the lengths needed to determine the volume.
  • For an irregular object submerge it in water and measure the displaced volume.
  • Measure the mass of either type of object using a measuring balance.

5.05 know and use the relationship between pressure, force and area:

pressure (Pa) = force (N)/ area (m2

  • Pressure is defined as force per unit area.
  • One pascal (Pa) is equivalent to one N/m2

5.06 understand how the pressure at a point in a gas or liquid at rest acts equally in all directions

Pressure in liquids:

Pressure in liquids acts equally in all directions as long as the liquid is not moving.

5.07 know and use the relationship for pressure difference: p = h × ρ × g

Pressure difference [Pa] = Density [kg/m3] x g [N/kg] x Height [m]

ΔP = ρ g h

  • The equation can be used in liquids or gases provided you know their densities.

P1 – Patm = ρ g h

P1 = ρ g h + Patm

Select a set of flashcards to study:


     Skills and equipment

     Remove Flashcards

Section 1: Principles of chemistry

      a) States of matter

      b) Atoms

      c) Atomic structure

     d) Relative formula masses and molar volumes of gases

     e) Chemical formulae and chemical equations

     f) Ionic compounds

     g) Covalent substances

     h) Metallic crystals

     i) Electrolysis

 Section 2: Chemistry of the elements

     a) The Periodic Table

     b) Group 1 elements: lithium, sodium and potassium

     c) Group 7 elements: chlorine, bromine and iodine

     d) Oxygen and oxides

     e) Hydrogen and water

     f) Reactivity series

     g) Tests for ions and gases

Section 3: Organic chemistry

     a) Introduction

     b) Alkanes

     c) Alkenes

     d) Ethanol

Section 4: Physical chemistry

     a) Acids, alkalis and salts

     b) Energetics

     c) Rates of reaction

     d) Equilibria

Section 5: Chemistry in industry

     a) Extraction and uses of metals

     b) Crude oil

     c) Synthetic polymers

     d) The industrial manufacture of chemicals

Go to Top