Topic: Pressure and Density

5.01 use the following units: degree Celsius (°C), Kelvin (K), joule (J), kilogram (kg), kilogram/metre3 (kg/m3), metre (m), metre2 (m2), metre3 (m3), metre/second (m/s), metre/second2 (m/s2), newton (N) and pascal (Pa)

The units for:

temperature: degree Celsius (°C) or Kelvin (K)

Energy: Joule (J)

mass: Kilogram (kg)

density: kilogram/metre cubed (kg/m3)

distance: metre (m)

area: metre squared (m2)

volume: metre cubed (m3)

velocity: metre per second (m/s)

acceleration: metre per second squared (m/s2)

force: newton (N)

pressure: pascal (Pa)

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.

5.07 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

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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

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