If the chemical equation below is balanced using only whole numbers, what is the smallest whole-number coefficient for water? __ Fe2O3 + __ H2 ---> __ Fe + __ H2O

Select one:
a. 1
b. 2
c. 3
d. 4

c. 3

Explanation:

Fe₂O₃ + H₂ ---> Fe + H₂O

1) I'd start with balancing the oxygen on both sides as there are three on the left and one on the right. Add 3 in front of H₂O to solve this. Now we have

Fe₂O₃ + H₂ ---> Fe + 3H₂O

Fe₂O₃ + H₂ ---> Fe + 3H₂O

2) Fe is not balanced as there are two Fe on the left and one Fe on the right. Add 2 in front of Fe to give

Fe₂O₃ + H₂ ---> 2Fe + 3H₂O

3) Fe₂O₃ + H₂ ---> 2Fe + 3H₂O

H is not balanced as there are two H on the left and 6 H on the right (3 × 2 = 6) so add 3 in H₂ to be equal

Fe₂O₃ + 3H₂ ---> 2Fe + 3H₂O

the equation is fully balanced

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons