Unit 2 : Properties of materials Flashcards
(16 cards)
What is dissolving?
Dissolving is when a solute breaks down and mixes completely with a solvent to form a solution.
What is a solute?
A substance that dissolves in a solvent (e.g. sugar or salt).
What is a solvent?
A substance that dissolves a solute (e.g. water).
What is a solution?
A mixture formed when a solute completely dissolves in a solvent.
What does ‘soluble’ mean?
A substance that can dissolve in a solvent.
What does ‘insoluble’ mean?
A substance that does not dissolve in a solvent.
What is solubility?
The maximum amount of solute that can dissolve in a solvent at a given temperature.
What factors affect solubility?
Temperature, type of solute, and type of solvent.
How does temperature affect solubility?
For most solids, solubility increases with temperature. For gases, solubility decreases as temperature increases.
What are the key variables in a solubility experiment?
Independent variable: the one you change (e.g. temperature)
Dependent variable: the one you measure (e.g. amount dissolved)
Control variables: the ones you keep the same (e.g. volume of water, type of solute)
What should you include in a good experiment plan?
A clear hypothesis, list of variables, method, equipment, safety precautions, and how you’ll collect and analyze results.
What is chromatography used for?
To separate and identify different substances in a mixture, especially colored substances.
How does paper chromatography work?
Substances in the mixture travel at different speeds on the paper depending on how well they dissolve in the solvent, separating into bands.
What is the solvent in chromatography?
A liquid (e.g. water or ethanol) that carries the mixture up the paper.
What is the Rf value and how is it calculated?
Rf = Distance travelled by substance ÷ Distance travelled by solvent
What does it mean if two spots have the same Rf value?
They are likely the same substance.
