Name three uses of hydrogen gas. Write the equation for the reaction of hydrogen with: (I) sodium metal, (II) copper (II) chloride solution, (III) chlorine gas. Give the reason why: (I) tin is used in the canning of food; (II) copper is used in the manufacture of wires?

here are the answers to the remaining questions:

5. a)

(i) To test for hydrogen, bring a lighted splint to the mouth of a test tube containing the gas. If hydrogen is present, it will extinguish the flame with a characteristic 'pop' sound.

(ii) Three uses of hydrogen gas are:

• As a fuel in rocket propulsion.
• In the Haber process for the industrial synthesis of ammonia.
• For the hydrogenation of vegetable oils to produce margarine.

(iii) Write the equation for the reaction of hydrogen with:
(I) sodium metal: $2\text{Na (s)} + \text{H}_2\text{ (g)} \rightarrow 2\text{NaH (s)}$ (II) copper (II) chloride solution:
Hydrogen is less reactive than copper, so it cannot displace copper from its salt solution. $\boxed{\text{No reaction}}$ (III) chlorine gas: $\text{H}_2\text{ (g)} + \text{Cl}_2\text{ (g)} \rightarrow 2\text{HCl (g)}$

b)

(i) Give the reason why:
(I) tin is used in the canning of food:
Tin is used because it is unreactive with food and non-toxic, preventing corrosion of the can and contamination of the food.
(II) copper is used in the manufacture of wires:
Copper is used because it is an excellent electrical conductor and is ductile, meaning it can be easily drawn into thin wires.

(ii) Name one ore of:
(I) iron: $\boxed{\text{Hematite}}$ ($\text{Fe}_2\text{O}_3$)
(II) tin: $\boxed{\text{Cassiterite}}$ ($\text{SnO}_2$)

(iii) Name one alloy of:
(I) iron: $\boxed{\text{Steel}}$
(II) copper: $\boxed{\text{Brass}}$