Midterm 2025

Question 1

What is the general equation for an acid + base reaction?

Answer 1

Acid + Base → Salt + Water

Question 2

Write the balanced equation for hydrochloric acid + sodium hydroxide.

Answer 2

HCl + NaOH → NaCl + H₂O

Question 3

Write the balanced equation for sulfuric acid + potassium hydroxide.

Answer 3

H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O

Question 4

What type of reaction occurs when an acid reacts with a base?

Answer 4

Neutralisation

Question 5

What is the general equation for an acid + metal reaction?

Answer 5

Acid + Metal → Salt + Hydrogen

Question 6

Write the balanced equation for hydrochloric acid + magnesium.

Answer 6

2HCl + Mg → MgCl₂ + H₂

Question 7

Write the balanced equation for sulfuric acid + zinc.

Answer 7

H₂SO₄ + Zn → ZnSO₄ + H₂

Question 8

Why do acids react with metals to produce hydrogen gas?

Answer 8

Because hydrogen ions (H⁺) from the acid gain electrons from the metal to form hydrogen gas (H₂).

Question 9

How can you test for hydrogen gas?

Answer 9

Use the pop test – if a burning splint is placed in the gas, it makes a squeaky pop sound.

Question 10

What is the general equation for an acid + metal carbonate reaction?

Answer 10

Acid + Metal Carbonate → Salt + Water + Carbon Dioxide

Question 11

Write the balanced equation for hydrochloric acid + calcium carbonate.

Answer 11

2HCl + CaCO₃ → CaCl₂ + H₂O + CO₂

Question 12

Write the balanced equation for sulfuric acid + sodium carbonate.

Answer 12

H₂SO₄ + Na₂CO₃ → Na₂SO₄ + H₂O + CO₂

Question 13

What gas is released when an acid reacts with a metal carbonate?

Answer 13

Carbon dioxide (CO₂)

Question 14

How can you test for carbon dioxide gas?

Answer 14

Bubble it through limewater; if CO₂ is present, the limewater turns cloudy.

Question 15

What ions do acids release in solution?

Answer 15

H⁺ (hydrogen ions)

Question 16

What ions do alkalis release in solution?

Answer 16

OH⁻ (hydroxide ions)

Question 17

What is the pH range for acids?

Answer 17

0-6

Question 18

What is the pH range for alkalis?

Answer 18

8-14

Question 19

What color does litmus paper turn in an acid?

Answer 19

Red

Question 20

What color does litmus paper turn in an alkali?

Answer 20

Blue

Question 21

What is the name of the indicator that turns pink in alkalis and colorless in acids?

Answer 21

Phenolphthalein

Question 22

What is the name of the indicator that turns red in acids and yellow in alkalis?

Answer 22

Methyl orange

Question 23

What is the reactivity series?

Answer 23

A list of metals in order of their reactivity.

Question 24

Name the top three most reactive metals.

Answer 24

Potassium (K), Sodium (Na), Lithium (Li)

Question 25

Name a metal that reacts with acid but not water.

Answer 25

Zinc (Zn) or Iron (Fe)

Question 26

Name a metal that does not react with acid or water.

Answer 26

Gold (Au) or Platinum (Pt)

Question 27

What happens when a more reactive metal is placed in a solution of a less reactive metal’s compound?

Answer 27

The more reactive metal displaces the less reactive one.

Question 28

Write the balanced equation for the reaction of magnesium with copper sulfate.

Answer 28

Mg + CuSO₄ → MgSO₄ + Cu

Question 29

What is oxidation?

Answer 29

The gain of oxygen or loss of electrons.

Question 30

What is reduction?

Answer 30

The loss of oxygen or gain of electrons.

Question 31

What does OIL RIG stand for?

Answer 31

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

Question 32

What is a redox reaction?

Answer 32

A reaction where both oxidation and reduction happen at the same time.

Question 33

In the reaction Mg + CuO → MgO + Cu, which element is oxidised and which is reduced?

Answer 33

Magnesium is oxidised, Copper is reduced.

Question 34

What is an acid

Answer 34

A substance that produces hydrogen ions, H+(aq), when dissolved in water

Question 36

Observations when acids react with metal and metal carbonates

Answer 36

With Metals: Hydrogen gas (H₂) is released, and the metal dissolves. With Metal Carbonates: Effervescence (bubbling) occurs due to the release of CO₂ gas.

Question 37

Hydrochloric acid

Answer 37

HCl

Question 38

Nitric Acid

Answer 38

HNO3

Question 39

Sukfuric Acid

Answer 39

H2SO4

Question 41

How does paint prevent rusting

Answer 41

Painting creates a barrier between the iron and the environment, preventing oxygen and water from coming into contact with the metal