C4: Neutralisation (and other acid reactions)

Question 1

What type of reaction occurs when an acid reacts with an alkali?

Answer 1

Neutralisation reaction

Question 2

What is a base?

Answer 2

A substance that neutralises an acid

Question 3

What is an alkali?

Answer 3

A substance that neutralises an acid. A soluble base.

Question 4

Give 2 examples of bases.

Answer 4

Copper oxide (CuO) Calcium oxide (CaO)

Question 5

Give an example of an alkali.

Answer 5

Sodium Hydroxide (NaOH)

Question 6

If an acid is added to an alkali does the pH increase or decrease?

Answer 6

Decrease

Question 7

If an alkali is added to an acid does the pH increase or decrease?

Answer 7

Increase

Question 8

A farmer wants to start growing sweetcorn on his farm. He has found out that sweetcorn grows best in soil with a pH value of 7.5. Explain how he can use knowledge of acids, alkalis, and neutralisation to find out the pH value of his soil to make sure he gets the best crop possible.

Answer 8

1. Use an indicator to determine the pH value of the soil. 2. Add an acid to reduce the pH value if it is too alkaline. 3. Add alkai to increase the pH value if it is too acidic. 4. Adding acid/alkali causes a neutralisation reaction and changes the pH value. 5. The pH value will change over time due to weather/leeching into the surrounding soil/plant or animal waste. 6. The pH value will need to be regularly monitored and adjusted.

Question 9

Suggest how environmental organisations could calculate the amount of alkali needed to raise the pH of an acidic lake.

Answer 9

1. Measure pH of lake water. 2. Select a suitable alkali that can be used to neutralise the pH. 3. Carry out an investigation to find out the exact volume of alkali needed to neutralise the sample volume. 4. Carry out a suitable number of repeats including from various locations to obtain an average pH/amount of alkali needed.

Question 10

Acid + Alkali –>

Answer 10

Salt + Water

Question 11

Magnesium + Hydrochloric Acid –>

Answer 11

Magnesium + Hydrochloric Acid –> Magnesium Chloride + Hydrogen

Question 12

What is the chemical formula for Sodium Chloride (table salt)?

Answer 12

NaCl

Question 13

Acid + Base –> ? + ?

Answer 13

Acid + Base –> Salt + Water

Question 14

Sulfuric Acid produces which type of salt?

Answer 14

Sulfate salts (ending in SO₄)

Question 15

Metal + Acid –> ? + ?

Answer 15

Salt + Hydrogen

Question 16

How can we test for hydrogen gas?

Answer 16

Collect the gas

Hold a lit splint next to it

Squeaky pop = hydrogen!

Question 17

Hydrochloric Acid produces which type of salt?

Answer 17

Chloride salts (ending in ‘Cl’)

Question 18

H⁺ + OH^- –> ?

Answer 18

H⁺ + OH^- ​–> H₂O

Question 19

Sulfuric Acid + Copper Oxide –> ? + ?

Answer 19

Sulfuric Acid + Copper Oxide –> Copper Sulfate + Water

Question 20

Nitric Acid produces which type of salt?

Answer 20

Nitrate salts (ending in NO₃)