Question

Balance the following equation in acidic solution using the lowest possible integers and give the coefficient of water. Cl2(aq) + S2O32- (aq) → Cl-(aq) + SO42-(aq)

Answer 1

Follow the steps as:

First, split the above equation in two parts and then balance individually and then combine as:

Cl2(aq) ---------> Cl-(aq)    ------(1) and S2O32-(aq) ---------->    SO42-(aq)    -------(2)

First balance eq (1) step by step as:

Cl2(aq) ---------> Cl-(aq)

Cl2(aq) ---------> 2Cl-(aq)    (balance Cl)

Cl2(aq) + 2e- ---------> 2Cl-(aq)       (balance charge) ------(3)

Now, balance equation (2) as:

S2O32-(aq) ---------->    SO42-(aq)

S2O32-(aq) ---------->    2SO42-(aq)       (balance S)

S2O32-(aq) + 5H2O ---------->    2SO42-(aq)                              (balance O)

S2O32-(aq) + 5H2O ---------->    2SO42-(aq)     +   10H+        (balance H)

S2O32-(aq) + 5H2O ---------->    2SO42-(aq)     +   10H+    +    8e- (balance charge)   -----------(4)

Now, multiply eq (3) by 4 as:

4Cl2(aq) + 8e- ---------> 8Cl-(aq) ----------(5)

Finally, add eq (4) and (5) and cancell the common things from either side to get the balanced equation as:   

4Cl2(aq) + S2O32-(aq) + 5H2O    ---------->    2SO42-(aq)     +   10H+ 8Cl-

coefficient of water = 5