In the explosion of a hydrogen-filled balloon, 0.40 g of hydrogen reacted with 3.2 g of oxygen. How many grams of water vapor are formed? (water vapor is the only product.) express your answer using two significant figures.

3.568 g of H₂O

Solution:

The Balance Chemical Equation is as follow,

2 H₂ + O₂ → 2 H₂O

Step 1: Calculate the Limiting Reagent,

According to Balance equation,

4.04 g (2 mol) H₂ reacts with = 32 g (1 mol) of O₂

So,

0.40 g of H₂ will react with = X g of O₂

Solving for X,

X = (0.40 g * 32 g) : 4.04 g

X = 3.17 g of O₂

It means 0.4 g of H₂ requires 3.17 g of O₂, while we are provided with 3.2 g of O₂ which is in excess. Therefore, H₂ is the limiting reagent and will control the yield of products.

Step 2: Calculate amount of Water produced,

According to equation,

4.04 g (2 mol) of H₂ produces = 36.04 g (2 mol) of H₂O

So,

0.40 g of H₂ will produce = X moles of H₂O

Solving for X,

X = (0.40 g * 36.04 mol) : 4.04 g

X = 3.568 g of H₂O