Question

How to Balance symbol equations?

Answer 1

$2\; \text{Ca} + \text{O}_2 \to 2\; \text{CaO}$

Try the following steps:

1. Set the coefficient in front of the species with the greatest number of different atoms to one. In this question consider assigning Calcium Oxide $\text{CaO}$ a coefficient of one for containing two elements.
2. Deduce, using the rule of atomic conservation, the coefficient in front of other species. The product side of this equation contains one calcium $\text{Ca}$ and one oxygen $\text{O}$ atom, so should the product side. Thus assign calcium $\text{Ca}$ a coefficient of $1$ and oxygen gas a coefficient of $1/2$- since $1/2 \; \text{O}_2 \times 2 \; \text{O atoms per O}_2 = 1 \; \text{O atom}$: $1 \; \text{Ca} + 1/2 \; \text{O}_2 \to 1\; \text{CaO}$
3. In case any of the coefficient contains fractions, multiply all coefficients in the equation with the least common multiple of their denominators to convert the coefficients into whole numbers. In this example, multiple all coefficients by $2$ to deduce the equation shown at the beginning of this answer: $2\; \text{Ca} + \text{O}_2 \to 2\; \text{CaO}$.