Question

C3H8 + 5 O2 → 3 CO2 + 4 H2O What is the number of atoms on each side of the equation?

Answer 1

Answer: 1.2642*10²⁵ on both sides

Explanation:

First check how many moles are there on each side.
Since this is a balanaced equataion the number of moles on each side is the same thus the number of atoms is also same on both sides

There are 3 moles of carbon and 8 moles of hydrogen in C3H8
and 2 moles of oxygen in O2 but there 5 infront so 2*5 is 10
Number of moles on the right is 10+8+3 = 21

Now use Avogrado's constant

21 Moles* (6.02*10²³)/Mol
= 21*6.02*10²³

= 1.2642*10²⁵

Answer 2

According to law of conservation of mass

• Mass of reactants=Mass of products

So

No of moles of reactants

• 3+8+10
• 21

No of moles of products

• 21

No of atoms

• 21×6.023×10²³
• 1.26×10²⁵atoms