Group 3--2P04 Answer Scheme

1. What can you conclude ablut the reaction between some dilute acids and some metals?

Ans:    Dilute acids react with reactive metals to produce salt and hydrogen gas.

2. Write the general equation for the reaction between dilute acid and metal.

Ans:    Dilute Acid + Metal --> Salt + Hydrogen Gas

3. How can you identify the gas formed when some dilute acids react with some metals?

Ans:    We can place a lighted splint inside the test tube and if hydrogen is present, a 'pop' will be heard.

4. From the effect of gas damp litmus paper, what can you conclude about the nature of hydrogen gas?

Ans:    Hydrogen gas is neutral.

5. Arrange the metals according to their reactivity in descending order. (most reactive first)

Ans:    Iron(Fe), Magnesium(Mg), Zinc(Zn), Copper(Cu)

Exercise

1(a) magnesium + hydrochloric acid --> magnesium chloride + hydrogen gas
  (b) Mg + 2HCl --> MgCl2 + H2

2(a) iron + hydrochloric acid --> iron(II) chloride + hydrogen gas
  (b) Fe + 2HCl --> FeCl2 + H2

3(a) zinc + hydrochloric acid --> zinc chloride + hydrogen gas
  (b) Zn + 2HCl --> ZnCl2 + H2

4(a) magnesium + sulfuric acid --> magnesium sulfate + hydrogen gas
  (b) Mg + H2SO4 --> MgSO4 + H2

5(a) iron + sulfuric acid --> iron(II) sulfate + hydrogen gas
  (b) Fe + H2SO4 --> FeSO4 + H2

6(a) zinc + sulfuric acid --> zinc sulfate + hydrogen gas
  (b) Zn + H2SO4 --> ZnSO4 + H2

7(a) magnesium + nitric acid --> magnesium nitrate + hydrogen gas
  (b) 2Mg + 2HNO3 --> 2MgNO3 + H2

8(a) iron + nitric acid --> iron(II) nitrate + hydrogen gas
  (b) 2Fe + 2HNO3 --> 2FeNO3 + H2

9(a) zinc + nitric acid --> zinc nitrate + hydrogen gas
  (b) 2Zn + 2HNO3 --> 2ZnNO3 + H2

Done by: Cheh Fu Yang
              Wesley Kam
              Nesman Ng
               joker Tan Zi Jie