SC1+2 Flashcards
(18 cards)
What are the three states of matter?
Solid, liquid, gas.
Describe particle arrangement in solids vs. gases.
Solid: Tightly packed, vibrate in fixed positions.
Gas: Far apart, move randomly at high speed.
What is sublimation? Give an example.
Solid → gas without becoming liquid (e.g., dry ice or iodine).
Why does temperature stay constant during melting?
Energy is used to break bonds, not raise temperature.
What is the difference between evaporation and boiling?
Evaporation: Surface-only, any temperature.
Boiling: Throughout liquid, at fixed boiling point.
What does a flat line on a heating curve represent?
Change of state (e.g., melting/boiling).
What is a mixture?
Two or more substances not chemically bonded (e.g., air, saltwater).
How can you separate sand and salt?
Filtration (sand = residue).
Evaporate water to leave salt.
What is the residue vs. filtrate in filtration?
Residue: Insoluble solid left on filter paper.
Filtrate: Liquid that passes through.
How does crystallisation work?
Evaporate solvent to form pure crystals (e.g., salt from seawater).
What is the stationary vs. mobile phase in chromatography?
Stationary: the paper (doesnt move)
Mobile: Solvent that moves up the paper (e.g., water or ethanol).
How do you calculate the Rf value?
Rf =
distance moved by the spot
———————————————
distance moved by the solvent
What is simple distillation used for?
Separating a liquid from a solution (e.g., water from saltwater).
Why is fractional distillation better for miscible liquids?
Different boiling points → separate ethanol/water.
What is the role of the condenser?
Cools vapours back to liquid.
How is drinking water purified?
Filtration (removes solids).
Chlorination (kills bacteria).
What is desalination?
Removing salt from seawater (e.g., reverse osmosis).
How would you identify unknown dyes in ink?
Use chromatography to compare Rf values to known samples.
