To determine whether the reaction \( \text{SnO}_2 + \text{H}_2 \rightarrow \text{Sn} + \text{H}_2\text{O} \) is balanced, we need to count the number of atoms of each element on both sides of the equation.
On the left side (reactants):
- Sn: 1 (from SnO2)
- O: 2 (from SnO2)
- H: 2 (from H2)
On the right side (products):
- Sn: 1 (from Sn)
- O: 1 (from H2O)
- H: 2 (from H2O)
Now, comparing both sides:
- Sn: 1 (reactants) = 1 (products)
- O: 2 (reactants) ≠ 1 (products)
- H: 2 (reactants) = 2 (products)
The reaction is not balanced because the number of oxygen atoms in the reactants (2) does not equal the number of oxygen atoms in the products (1). Therefore, we affirm that:
It is unbalanced due to the fact that the mass of the reactants exceeds the mass of the products.