# Zn + HCl → ZnCl2 + H2 Can you show how this balances out?

### 1 Answer

- lenpol7Lv 73 years agoFavorite Answer
Zn + HCl = ZnCl2 + H2

#1 ; Zinc /Zn ; 1 x Zn on each side ; Balanced.

#2 ; Hydrogen/H ; 1 x H on the LHS , but 2 x H (as H2) on the RHS

So we put a '2' on the LHS in front on 'HCl' . This indicates two hydrogens to start.

It also indicates ' 2 x Cl'

#3 ; Chlorine/Cl ; 2 x Cl on the RHS (ZnCl2), and as deduced from '#2' there are now '2 Cl' on the LHS.

So the BALANCED equation is

Zn + 2HCl = ZnCl2 + H2

Another way of doing this is : -

Zn + (H-Cl) + = (Cl-Zn-Cl) + (H-H) To start.

Notice that there are 2 x Cl on the RHS and 2 x H also on the RHS.

So to Balance we mu put in another H-Cl on the LHS

Hence

Zn + (H-Cl) + (H-Cl) = (Cl-Zn-Cl) + (H-H)

Since there are two lots of (H-Cl) on the LHS we write '2HCl'

NB

The Prefix (Large) number indicates the number of molecules required to balance.

The Suffix Subscript number indicates the number of atoms of the same element within a given molecule.

NNB

All chemical reactions follow the Law of Conservation of Mass. That means the total mass of reactants MUST be the same as the total mass of the products. Hence it follows that you must have the same numbers and type of atoms on each side of the reaction equation.

Casually, the atoms just 'swop partners'!!!!

Hope that helps!!!