Topics to revise
Particle Model (Physics)
Quantitative chemistry
Required practical - Density
Required practical - Exothermic reactions
If you took a break in half term, that's ok, but back to it now.
Density of regular and irregular objects
Use appropriate apparatus to determine the density of regular/irregular solids and liquids.
Check your understanding with these quick common questions. Use the drop down boxes to see the correct answers.
Density
Density depends on the mass and volume of an object. The closer packed the particles, the more dense it is. You might be asked to measure the density of regular or irregular objects. The formula is Density = mass/ volume. The standard units are kg and m3
This is more of a procedure than an investigation,
Eureka can
Calippers (or ruler)
Measuring cylinder
Mass balance
For regular objects, you might need to use a formula to calculate volume, like the volume of a sphere. This will be given to you. For a cuboid you will need to use length x width x height.
Measure mass on a balance.
For regular solids: measure dimensions and calculate volume.
For irregular solids: use a displacement can/cylinder (or Eureka can) to find volume.
Collect the displaced water in a measuring cylinder.
Calculate density using Density = Mass /Volume.
Remember to use the correct units kg and m3
Temperature changes
This is an investigation looking at the temperature change in an endo and exothermic reaction.
Check your understanding with these quick common questions. Use the drop down boxes to see the correct answers.
Exo and endothermic reactions
You could be asked to investigate
Acids + Metal
Acids + Carbonates
Acids + Alkalis (neutralization)
Displacement reactions
Independent variable: Starting temperature or concentration of one reactant.
Dependent variable: Temperature change (°C).
Thermometer or temperature probe, insulated cup or polystyrene beaker, lid.
Improve accuracy: Use a digital temperature probe.
Control validity: Keep reactant volumes and concentrations constant. The main weakness is the loss of heat by not having a lid. Have a lid.
The bigger the temperature change in the reaction, the more energy is absorbed or released. Remember that endothermic reactions absorb energy from the surroundings, and exothermic reactions transfer heat into the surroundings.
Measure known volumes of reactants into an insulated cup.
Record initial temperature.
Mix chemicals, replace lid, and record highest or lowest temperature reached.
Calculate the temperature change.
Repeat for different solutions
Record three repeats for each solution and calculate a mean