Some Chem Questions

1. KMnO4 + HCl = KCl + MnCl2 + H2O + Cl2

First to find out what is unique in both side of the reaction
in this case, O in MnO4- ion on the left and O in H2O on the right
4 O in KMnO4 on the left to form 4 O in 4 H2O on the right
a) KMnO4 --> 4 H2O
8 H in 4 H2O on the right from 8H in 8 HCl on the left
b) KMnO4 + 8 HCl --> 4 H2O
1 K & 1 Mn in KMnO4 on the left to form 1 K & 1 Mn in 1 KCl & 1 MnCl2 on the right
c) KMnO4 + 8 HCl --> KCl + MnCl2 + 4 H2O
8 Cl in 8HCL on the left and only 3 Cl on the left, so 5 Cl for the formation of 2 1/2 Cl2
d) KMnO4 + 8 HCl --> KCl + MnCl2 + 4 H2O + 2 1/2 Cl2
For the unity of each reagant, the whole equation has to be multiplied by 2
e) 2 KMnO4 + 16 HCl --> 2 KCl + 2 MnCl2 + 8 H2O + 5 Cl2


For 2 to 5, similar to above but much easy to balance, you can try yourself =)
2. Ca(OH) + H3PO4 = Ca3(PO4) + H2O

3 Ca(OH) + H3PO4 --> Ca3(PO4) + 3 H2O


3. Ca(OH)2 + HCl = CaCl2 + H2O

Ca(OH)2 + 2 HCl --> CaCl2 + H2O


4. FeCl3 + NH4OH = Fe(OH)3 + NH4Cl

FeCl3 + 3 NH4OH --> Fe(OH)3 + 3 NH4Cl


5. Na + HCl = NaCl + H2

2 Na + 2 HCl --> 2 NaCl + H2

I hope this can help your understanding. :)