Reaction of Metals with Dilute Acids

Question 1 Name the metal which has been placed at the top of reactivity series?

Question 2 Name the metal which has been placed at the bottom of reactivity series?

Question 3 Which of the two metals is more reactive: Copper or silver?

Question 4 What happens when sodium react with HCl?

Question 5 What happens when magnesium react with HCl?

Question 6 What happens when aluminium react with HCl?

Question 7 What happens when zinc react with HCl?

Question 8 What happens when iron react with HCl?

Question 9 Write an equation for reaction of sodium with sulphuric acid?

Question 10 Write an equation for reaction of zinc with sulphuric acid?

Question 11 Write an equation for reaction of magnesium with sulphuric acid?

Question 12 What is an activity series?

Reaction of metals with Dilute Acids

Metals usually displace hydrogen from dilute acids.

Less reactive metal(Cu, Au, Ag) do not displace hydrogen from dilute acid.

2Na+2HCl——>2NaCl + hydrogen (react violently)

Mg(s) + + 2 HCl (aq) —–> MgCl₂ (aq) + H₂ (g)

Al(s) + 6 HCl (aq) —-> AlCl₃ (aq) + 3 H₂ (g)

Zn(s) + 2 HCl (aq) —-> ZnCl₂  (aq) + H₂ (g)

Fe (s) + 2 HCl (aq) —-> FeCl₂  (aq) + H₂ (g)

Silver and gold do not react with dilute acids.

The metals like Cu, Au, Ag are less reactive than hydrogen. They do not displace hydrogen from dilute acids.

Those metals which are above in the reactivity series displace hydrogen from dilute acids.

2Na (s) + H₂SO₄  (aq) ——> Na₂SO₄ (aq) + H₂ (g)

Mg (s) + H₂SO₄  (aq) ——> MgSO₄ (aq) + H₂ (g)

2Al (s) + 3 H₂SO₄  (aq) ——> Al₂(SO₄)₃ (aq) + H₂ (g)

Zn(s) + H₂SO₄  (aq) ——>  ZnSO₄ (aq) + H₂ (g)

Cu (s) + H₂SO₄  (aq) ——>  no reaction

When a metal react with dilute nitric acid, then hydrogen gas is not evolved. Nitric acid is a strong oxidising agent. As soon as hydrogen gas is formed in reaction between metal and dilute nitric acid, the nitric acid oxidises this hydrogen to water. Nitric acid itself is reduced to nitrogen oxides such
as nitrogen monoxide, dinitrogen monoxide.

The arrangement of metals in decreasing order of their reactivities is called reactivity series or activity series of metals.

K

Na

Ca

Al

Zn

Fe

Sn

Pb

H

Cu

Hg

Ag

This is a decreasing order of chemical reactivity. K is most reactive whereas Au is least reactive.

1) If a metal atom can lose electron easily to form positive ion, it will react rapidly with other substances and hence is a reactive metal.

2) If a metal atom losses electron less readily to form positive ion, it will react slowly with other substances and hence is less reactive metal.

3) Those metals which lose electrons more readily than hydrogen are said to be more reactive than hydrogen (metals placed above hydrogen are more reactive than hydrogen)

4) Those metals which lose electrons less readily than hydrogen are said to be less reactive than hydrogen (metals placed below hydrogen are less reactive than hydrogen)