Question

Balance the following equations.

a. SO2 + H2S →S + H2O

b. Ag + HCl →AgCl + H2

c. NaOH + H2SO4→ Na2SO4 + H2O​

Answer 1

a.We want to balance the equation SO2+H2S=S+H2O.

It can be seen that on the RHS, the number of hydrogen atoms is twice the number of oxygen atoms.

⇒ On the LHS the number of molecules of H2S should be twice the number of molecules of SO2.

So, as an intermediate step, we tentatively put SO2+2H2S=S+H2O.

Now we see that there are four atoms of hydrogen and two atoms of oxygen in the LHS.

⇒ We should have two molecules of water on the RHS.

So, we modify the equation to SO2+2H2S=S+2H2O.

Now there are three sulphur atoms on the LHS.

⇒ There should be three sulphur atoms on the RHS also.

So we get the balanced equation SO2+2H2S=3S+2H2O.

b.Ag + HCl →AgCl + H2

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