Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

8.8Chapter 8: Pure Substances and Solutions

Investigating solubility and temperature — Alhussan Chemistry - Stage 8 Revision Notes & Topical Questions

5 min read 8 parts Lesson 8 of 10 3 quizzes

📚 Alhussan Chemistry - Stage 8 Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
0%read
Lesson summary

8.8 Investigating solubility and temperature — Doing an Investigation — Alhussan International Academy — Chemistry (Stages 7–9) notes: Plan and carry out an investigation of how water temperature affects the mass of a solid that dissolves, choosing variables and equipment.Questio…

  • Background
  • Prediction
  • Possible variables
  • Independent variable
  • Control variable
  • Measuring cylinder

Part 1 of 6Scientific question and prediction

Question
  • Question how does water temperature affect the mass of sodium carbonate (Na2CO3) that dissolves?
Background
  • Background for most substances solubility increases with temperature, so sodium carbonate might behave in the same way.
Prediction
  • Prediction as the temperature of the water increases, the mass of sodium carbonate that dissolves will increase.

Part 2 of 6Considering variables

Variable
Variable anything that might affect what happens in an investigation.
Possible variables
  • Possible variables water temperature, water volume and the mass of solid that dissolves.
Independent variable
Independent variable the variable you change, here the water temperature.
Dependent variable
Dependent variable the variable you measure, here the mass of solid that dissolves.
Control variable
  • Control variable a variable kept the same to make a fair test, here the volume of water.
  • Other controls are the type of solute, the stirring and the way saturation is judged.
Range
  • Range choose at least five temperatures, for example 20 to 60 °C, to give a clear graph.

Part 3 of 6Choosing equipment

Measuring cylinder
  • Measuring cylinder it is chosen to measure the water volume because it measures smaller differences in volume than a beaker.
Thermometer
  • Thermometer choose one with a suitable range, such as 0 to 100 °C, because a clinical thermometer only measures 35 to 42 °C.
Mass measurement
  • Mass measurement a balance with weights measures changes as small as 1 g and works without electricity.
  • An electric balance measures smaller differences, but may not be reliable if the electricity supply is poor.
Heating and mixing
  • Heating and mixing a Bunsen burner or water bath heats the water, and a stirring rod stirs the mixture.

Part 4 of 6Method

1
Measure out a fixed volume of distilled water, for example 100 cm3, in a measuring cylinder and bring it to the first temperature, such as 0 °C.
2
Use a thermometer to check the temperature of the contents, keeping the tube in a water bath at that temperature.
3
Add the solid in small, weighed portions, 1 g at a time, stirring for about a minute after each.
4
Continue until a little solid remains undissolved after stirring, which shows the solution is saturated.
5
Calculate the total mass added before it stopped dissolving.
6
Change the water bath temperature, repeat, and repeat the whole experiment at least once.
  • Results table
    • it needs the independent variable in the left column, the dependent variable in the right column and units in the column headings.

Part 5 of 6Safety

Eye protection
  • Eye protection wear it throughout.
Hot water
  • Hot water use a heatproof mat and handle hot water with tongs or a boiling tube holder.
Harmful salts
  • Harmful salts some salts irritate the eyes or are harmful if swallowed, so wash hands afterwards.
Burners
  • Burners do not leave them unattended, and clear up spills.
Risk assessment
  • Risk assessment identify each hazard, say how it could cause harm and state a precaution.

Part 6 of 6Collecting reliable data

Reading instruments
  • Reading instruments read the thermometer at eye level, wait for it to settle, and record to its precision.
Same conditions
  • Same conditions use dry, finely ground solute, stir at a similar rate and wait the same time each time.
Odd results
  • Odd results repeat any result that looks odd.
Source of errorEffectImprovement
Temperature falls during the testSolubility too lowKeep in a water bath or insulate
Judging saturation by eyeVariable end-pointUse the same observer and small steps
Large portions of solidLow resolutionUse smaller portions

Key terms

TermMeaning
Saturated solutiona solution that cannot dissolve more solute at that temperature.
Independent variablethe variable that is changed.
Dependent variablethe variable that is measured.
Control variablea variable kept the same in a fair test.
Water batha beaker of water used to heat or hold a temperature.
Risk assessmentidentifying hazards and precautions.

Avoid these mistakes

1
Adding all the solid at once — add small portions and stir after each.
2
Not keeping the volume of water constant — this is the control variable.
3
Not stirring for the same time — the end-point would be judged differently.
4
Reading the thermometer without waiting for it to settle — the temperature would be wrong.

?What do you want to solve now?

Practice questionsTraining questions with instant feedback - not an exam. Official exam - gradedCheckpoint Quiz in MasterStudy: your mark is saved to your progress.

Last updated: