5. Acids, Bases & Salts

Question 1

What makes a substance acidic?

Answer 1

H+ ions

Question 2

What makes a substance alkali?

Answer 2

OH- ions

Question 3

H+ + OH- –>

Answer 3

H2O

Question 4

What is a neutralisation reaction

Answer 4

Acid + Base –> Salt

Question 5

Give 3 examples of acids

Answer 5

HCl
H2SO4
HNO3

Question 6

Give 3 examples of alkali

Answer 6

NaOH
KOH
Ca(OH)2

Question 7

What is a base?

Answer 7

A substance that neutralises acids

such as metal hydroxides and oxides

Question 8

What are alkalis?

Answer 8

Bases that are soluble in water

Question 9

What does the salt created depend on?

Answer 9

The metal in the base

The Acid used

Question 10

What are ammonium salts used as?

Answer 10

Fertilisers

Question 11

How do you measure the volumes of acid or alkali solutions that react with each other, needed to neutralise each other?

Answer 11

Titration

Question 12

How is titration carried out?

Answer 12

Measure the amount of alkali using a measuring cylinder
Place into a conical flask, add few drops of a suitable indicator
Add the acid to the burette, fill below eyeliner, read measurement at eye level from the bottom of the meniscus
Drop acid drop by drop
While swirling the solution
above a white tile
Close the tap when colour of indicator changes with 1 drop
Repeat experiment to get concordant results

Question 13

Making soluble salts: Acids with metals

Answer 13

Metal + Acid –> Salt + Hydrogen

DANGEROUS: if the metal is too reactive because the reaction is exothermic

Question 14

How do you make a soluble salt using Acids and Metals?

Answer 14

Add metal until in excess (no more bubbling) so all the acid has reacted
Filter to remove the unreacted metal, leaving salt solution
Heat the solution in evaporating dish to remove some of water then all to cool to form crystals
Filter to remove crystals and then dry them, of leave in warm place for water to evaporate

Question 15

Making soluble salts: Acids with insoluble bases

Answer 15

Metal oxide + Acid –> Salt + Water

Question 16

How do you make a soluble salt using an Acid and an Insoluble base?

Answer 16

Add Metal Oxide until in excess (no more bubbling) so all the acid has reacted
Filter to remove the unreacted Metal Oxide, leaving salt solution
Heat the solution in evaporating dish to remove some of water then all to cool to form crystals
Filter to remove crystals and then dry them, of leave in warm place for water to evaporate

Question 17

Making soluble salts: Acids with insoluble Metal Carbonates

Answer 17

Metal Carbonate + Acid –> Salt + Water + Carbon Dioxide

Question 18

How do you make a soluble salt using an Acid and an Insoluble Metal Carbonate?

Answer 18

Add Metal Carbonate until in excess (no more bubbling) so all the acid has reacted
Filter to remove the unreacted Metal Carbonate, leaving salt solution
Heat the solution in evaporating dish to remove some of water then all to cool to form crystals
Filter to remove crystals and then dry them, of leave in warm place for water to evaporate

Question 19

Why don’t all Metal Carbonates thermally decompose in labs?

Answer 19

Not all of them are broken down by the temperatures reached by a bunsen burner

Question 20

Which Metal Carbonates decompose in similar ways?

Answer 20

Carbonates of Magnesium, Copper, Zinc, Calcium, and Lithium