Acids (chemical changes)

Question 1

titration calculations

Answer 1

• underline in seperate colours
• calculate moles of one (divide by 1000 to get in dm^3)
  -use molar ratio to find moles of the other
• use formula to find concentration (divide by 1000 to get in dm^3)
• to find in g/dm^3, multiply mol/dm^3 by RFM of substance

Question 2

equation linking moles,
concentration and volume

Answer 2

m=cv

Question 3

why are alkali metals never reacted with acids

Answer 3

Alkali metals are too reactive and cannot be carried out safely

Question 4

what are the conditions needed for a reaction between an acid and a metal

Answer 4

the metal must be more reactive than the hydrogen in the acid otherwise no reaction will take place

Question 5

what forms when you react a metal with an acid

Answer 5

a salt and hydrogen

Question 6

how do you obtain a sample of the salt

Answer 6

can be crystalised out of the solution by evapouration

Question 7

what is a redox reaction

Answer 7

reaction between a metal and an acid

Question 8

what happens in a redox reaction

Answer 8

metal atoms lose electrons and are oxidised
the hydrogen ions in the acid gain electrons and are reduced

Question 9

OILRIG

Answer 9

Oxidation
Is
Loss
(of electrons)
Reduction
Is
Gain
(of electrons)

Question 10

how to formulate ionic equations

Answer 10

• write out normal equation
• write out equation taking oxidation and reduction into account
• delete spectator ions
• write out equation

Question 11

neutralisation equation

Answer 11

acid + base → salt + water

Question 12

mixture

Answer 12

two or more substances not chemically combined together

Question 13

differences between mixtures and compounds

Answer 13

• compounds have a fixed composition
• mixtures have no fixed composition
• compounds can only be separated by a chemical reaction
• mixtures can be separated more easily
• there are chemical bonds between atoms in a compound
• there are no chemical bonds between atoms in a mixture

Question 14

methods of separating mixtures

Answer 14

• filtration
• distillation
• crystallisation
• chromatography

Question 15

when would you use filtration

Answer 15

1 soluble, 1 insoluble

Question 16

when would you use distillation

Answer 16

when you need to collect the solvent from crystallisation

Question 17

when would you use crystallisation

Answer 17

to obtain pure salt

Question 18

how is filtration carried out

Answer 18

poured into a conical flask via a filter funnel with filter paper

Question 19

how is crystallisation carried out

Answer 19

by evapourating the water from the solution using a evapourating dish over a beaker of water over a bunsen burner

Question 20

how is distillation carried out

Answer 20

using a condenser to collect pure water