Acids, Bases & Salts

Question 1

What are the numbers for strongly acid, weakly acidic, neutral, weakly alkaline and strongly alkaline in universal indicator?

Answer 1

Strongly acidic 0-3
Weakly acidic 4-6
Neutral 7
Weakly alkaline 8-10
Strongly alkaline 11-14

Question 2

What is an acid?

Answer 2

Source of H+ ions
Proton donor

Question 3

What is a base?

Answer 3

Neutralise acids
Proton accepters

Question 4

What is an alkali?

Answer 4

Soluble bases
Source of OH- ions

Question 5

What colour does universal indicator go in acidic, neutral and alkaline solutions?

Answer 5

Acidic - red, orange, yellow
Neutral - green
Alkaline - blue, purple

Question 6

What colour does phenolphthalein go in acidic and alkaline solutions?

Answer 6

Acidic - colourless
Alkaline - pink

Question 7

What colour does methyl orange go in acidic and alkaline solutions?

Answer 7

Acid - red
Alkali - yellow

Question 8

What is a metal oxide?

Answer 8

pH greater than 7

Question 9

What is a non-metal oxide?

Answer 9

pH less than 7

Question 10

Acid + alkali to?

Answer 10

Salt + water

Question 11

Acid + base to?

Answer 11

Salt + water

Question 12

Acid + metal to?

Answer 12

salt + hydrogen

Question 13

Acid + metal carbonate to?

Answer 13

salt + water + carbon dioxide

Question 14

How do you make a soluble salt from an insoluble base?

Answer 14

Excess method
1. Warm acid to increase rate of reaction
2. Add base until it’s in excess (no more will react), to make sure all the acid reacts
3. Filter the mixture so the excess base is removed
4. Concentrate solution by boiling it, until crystals form when cooled (test with glass rod) but don’t boil off all water
5. Leave solution to form crystals

Question 15

How do you make a soluble salt from a soluble base?

Answer 15

Titration method
To make ammonium, sodium or potassium salts
1. Add your known volume of alkali to a conical flask with a few drops of indicator
2. Add acid from beretta until contents of conical flask changes colour to neutral
3. Not volume of acid & alkali that reacted together
4. Mix volumes in a clean flask (with no indicator)
5. Evaporate until crystals form on cooling

Question 16

How do you make an insoluble salt?

Answer 16

Precipitation method
1. Make sure both components are in solution (dissolved water)
2. Mix 2 solution in a beaker
3. Use filter paper & funnel to get the precipitate
4. Wash precipitate with distilled water (wash of excess ions)
5. Leave salt to dry on filter paper

Question 17

How do you do crystallisation?

Answer 17

1. Heat and boil some water in an evaporating basin
2. Stop boiling when crystals form on a glass rod
3. Leave to dry on windowsill
4. Pick crystals out then blot dry OR filter