Given the following unbalanced chemical reaction: As + NaOH Na3AsO3 + H2 What would be the coefficient of the NaOH molecule in the balanced reaction?

a. 1

b. 2

c. 4

d. 6

Answer: -

6

Explanation: -

The given unbalanced chemical equation is As + NaOH - - > Na3AsO3 + H2

We see there 3 sodium on the right side from Na3AsO3.

But there are only 1 sodium on the left from NaOH.

So we multiply NaOH by 3.

As + 3 NaOH - - > Na3AsO3 + H2

Now we see the number of Hydrogen on the left is 3.

But the number of hydrogens is 2 on the left.

So, we multiply to get both sides 6 hydrogen.

As + 6NaOH - - > Na3AsO3 + 3 H2

Rebalancing for Na,

As + 6NaOH - - > 2Na3AsO3 + 3 H2.

Finally balancing As,

2 As + 6 NaOH - - > 2Na3AsO3 + 3H2

The coefficient of the NaOH molecule in the balanced reaction is thus 6