Flashcards
Chemistry Unit 2
Cards in this deck (26)
- 1What happens to the particles in a solid when it melts?The particles gain energy to overcome the weak attractive forces and move further apart as a solid becomes a liquid.
- 2In a pure substance, what is the melting point like?Sharp and definite.
- 3Does a mixture have a fixed melting point?No, it melts over a range of temperatures.
- 4What does a pure substance have?The same fixed composition in all parts.
- 5What can NOT happen to a pure substance?It can not be separated into different substances using physical methods.
- 6What does a mixture contain?Elements and compounds that are not chemically combined and that CAN be separated using physical methods.
- 7What are the three states of matter?Gases, liquids and solids.
- 8What are the particles like in a solid?The particles are close together and regularly arranged. They can only vibrate about fixed positions.
- 9What are the particles like in a liquid?The particles are randomly arranged but close together. The particles can only move around each other.
- 10What are the particles in a gas like?The particles are far apart and can move quickly in all directions. They are randomly arranged.
- 11What is chromatography?The separation of soluble substances.
- 12What is the solvent in chromatography?The mobile phase.
- 13What does the paper contain in chromatography?The stationary phase.
- 14How does chromatography work?Running a solvent through chromatography paper causes the substances to move at different rates.
- 15What makes a component move further up the chromatography paper?If the component is soluble in the solvent.
- 16How do you calculate the RF (retardation factor) value?Distance travelled by spot
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Distance travelled by the solvent - 17Why does water have to be distilled?So it is pure.
- 18What happens durning distillation?The water is boiled and turns to gas and the minerals are left behind. The water vapour is then condensed.
- 19What is the word equation for distillation?Distillation= evaporation + condensation
- 20What does fractional distillation do?Separates two or more liquids from a mixture.
- 21What happens during fractional distillation?Liquids with lower boiling points are evaporated first. The mixture is separated into different fractions which can be pure or mixtures.
- 22When is fractional distillation used in real life?When making alcoholic drinks or separating gases.
- 23What is potable water?Drinking water.
- 24What is filtration?Water is sprayed onto sand and gravel. As it trickles through, the insoluble solids are removed
- 25What is sedimentation?A chemical is added which causes small particles to clump together into larger particles.
- 26What is chlorination?Chlorine gas is injected to sterilise the water. The chlorine kills the microbes left in the water.