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Food Chemistry

Measuring volume, separating mixtures, chemical changes, indicators and pH, and acid reactions.

  • SEC G1 Science 2027
  • 6 lessons
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Before you begin

Start by measuring volume and choosing methods to collect useful materials. Then learn paper chromatography, chemical changes, indicators and acid reactions. Use the substance properties and the product you need to choose a separation method.

Learning goals
  • Measuring volume
  • Dissolving
  • Filtration
  • Evaporation
  • Distillation
  • Everyday uses of separation
  • Paper chromatography
  • Chemical reactions
  • Slowing food decay
  • Slowing cooking and burning
  • Slowing rusting
  • Indicators
  • Measuring pH
  • The pH scale
  • Acid and metal
  • Acid and base
  • Acid and carbonate
  • Neutralisation
Syllabus statements covered
  • use a measuring cylinder to measure volume of liquid/solid
  • explain that substances can be separated from a mixture through the following techniques: — dissolving
  • explain that substances can be separated from a mixture through the following techniques: — filtration
  • explain that substances can be separated from a mixture through the following techniques: — evaporation
  • explain that substances can be separated from a mixture through the following techniques: — distillation
  • state some uses of separation techniques in homes and food industries (e.g. remove tea leaves from a cup of tea, obtain water from seawater)
  • explain that substances can be separated from a mixture through the following techniques: — paper chromatography
  • describe a chemical reaction as a process that leads to the formation of new products
  • state the following everyday changes that involve chemical reactions and how they can be slowed down: — decaying of food slowed down by food preservation methods (see also LO 2.3(d))
  • state the following everyday changes that involve chemical reactions and how they can be slowed down: — cooking of food and burning of fuel slowed down by reducing oxygen/fuel supply
  • state the following everyday changes that involve chemical reactions and how they can be slowed down: — rusting of iron cans slowed down by tin-plating
  • describe the properties of acids and alkalis in terms of their effects on litmus paper and universal indicator solution
  • use universal indicator solution and a pH meter to measure pH
  • describe acidity, neutrality and alkalinity in terms of the pH scale
  • describe the characteristic properties of acids in terms of their reactions with metals, bases and carbonates that are found in daily lives: — metals (e.g. cooking utensil)
  • describe the characteristic properties of acids in terms of their reactions with metals, bases and carbonates that are found in daily lives: — bases (e.g. toothpaste, antacid)
  • describe the characteristic properties of acids in terms of their reactions with metals, bases and carbonates that are found in daily lives: — carbonates (e.g. baking soda, effervescent vitamin C tablet) [knowledge of general products is required; chemical names of salts and equations are not required]
  • state that neutralisation takes place when an acid reacts with a base and the products can be salt and water only

Lessons

Work through them in order.

  1. Measuring liquid and solid volumeRead a measuring cylinder at the meniscus and find the volume of an irregular solid by displacement.
  2. Recovering solids and liquids from mixturesUse dissolving, filtration, evaporation and distillation to collect the required solids or liquids.
  3. Paper chromatography of food dyesRun a valid paper chromatogram and compare separated food dyes with known samples under the same conditions.
  4. Chemical changes and ways to slow themDistinguish chemical reactions from physical changes, and explain how to slow decay, fuel-fired cooking, burning and rusting.
  5. Indicators and pHTest solutions with litmus, universal indicator and a pH meter, and classify them as acidic, neutral or alkaline.
  6. Acid reactions and neutralisationPredict products from the other reactant, identify gases with evidence, and distinguish neutralisation from the final pH.

Practise and check

Recommended nextFood Chemistry topic check

Topic reference

Topic picture

Choose a separation route for the product you needTo recover salt from salt and sand, add water to dissolve the salt, then filter. Sand is the residue; salt solution is the filtrate. Evaporate water from the filtrate to collect salt. To recover water from a salt solution, boil water into vapour and then cool and condense the vapour into a receiving container. To separate soluble food dyes, use paper chromatography and compare the separated spots.Collect solids from salt mixed with sandAdd water and stirSalt dissolves;sand remains insolubleFilterSand: residue on the paperCollect; wash and dry if requiredSalt solution: filtratePasses through the paperEvaporate water from the filtrateCollect the salt left behindCollect water from a salt solution: distillationSalt solutionBoil waterinto vapourCool vapourand condenseCollect liquidwaterSeparate soluble food dyes: paper chromatographyFood-dye mixtureRun chromatographywith a suitable solventSeparated spotsCompare with standards
Scroll diagram horizontally to read all labels.
Dissolving and filtration separate insoluble material from a solution. Evaporation leaves a dissolved solid; distillation collects the solvent by boiling and condensation. Paper chromatography separates components that travel differently with a solvent.