Introduction Flashcards
1
Q
what are good observations to make when describing substances in practical work?
A
- solid, liquid, gas?
- coloured or colourless?
- crystalline or powdered? (for solids)
- clear or cloudy? (for liquids)
2
Q
good observations to make when describing changes during practical work?
A
- is there any fizzing?
- has a solid appeared or disappeared?
- has anything changed colour?
- are there any unusual sounds or smells?
3
Q
how to tell if something is a physical change?
A
- creates no new substances
- are usually easy to reverse
- absorb or release small amounts of energy
4
Q
how to tell if something is a chemical change?
A
- creates new substances
- are usually difficult to reverse
- absorb or release large amounts of energy
5
Q
what is a chemical test for water?
A
anhydrous copper(II) sulphate turns from white to blue (this tells you that water is present but NOT how pure it is)
6
Q
what are two physical tests for water?
A
- melting point = 0 degrees celcius
- boiling point - 100 degrees celcius
(purer water matches these properties more closely)