1
Q
What is an indicator?
A
-dye that changes colour depending on pH of substances
2
Q
Give some examples of indicators and how they work?
A
- universal indicator is a combination of dyes, colour change gradually as pH changes, useful for estimating pH of solutions, add a drop of indication to a solution and compare it to a colour chart to work out pH
- some change colour suddenly at a particular pH
3
Q
What is an acid?
A
- substance with pH less than 7
- forms H+ ions in water
- pH determined by concentration of H+ ions
4
Q
What is a base?
A
-substance with pH greater than 7
5
Q
What is an alkali?
A
- a base that is soluble in water
- forms OH- ions in water
6
Q
What do acid and ammonia produce?
A
-ammonium salt
7
Q
What do acids and carbonated produce?
A
-carbon dioxide, salt and water
8
Q
What do acids and metal oxide, and acids and metal hydroxide produce?
A
-salt and water
9
Q
What are metal oxides and hydroxides and how do they respond to water and acid?
A
- some metal oxides and hydroxides dissolve in water
- these soluble compounds are alkalis
- some bases that don’t dissolve in water still react with acids
