Condition : graphite + hydrogen gas
Chemical formula : C + H2
Reaction formula :
C + H2 -> C2H6
#First, you see the number of atom
•Product
C = 1
H = 2
•Reactant
C = 2
H = 6
#Note that, in a chemical reaction both number of each atom in product must be equal in reactant so, you think what number you need to put Infront of the chemical formula so that the number of atom equal
2C + 3H2 -> C2H6
#Now check again
•Product
C = 2
H = 6
•Reactant
C = 2
H6
#Now, its equal. The bold one is the balance chemical reaction
Reactant -> product (the thing you get after reaction)