Question

A hydrogen-filled balloon is ignited and 1.50 g of hydrogen reacts with 12.0 g of oxygen. How many grams of water vapor form? (assume that water vapor is the only product.)

Answer 1

The balanced chemical reaction between hydrogen and oxygen to form water is given as:

`H_2(g)+(1)/(2)O_2(g)\rightarrow H_2O(g)`

From the balanced chemical equation it is clear that one mole of hydrogen reacts to give 1 mole of water.

Since, number of moles =
`(mass of the substance)/(Molar Mass)`

So, number of moles of hydrogen =
`(mass of the hydrogen)/(Molar Mass of hydrogen)`

Mass of hydrogen =
`1.50 g` (given)

Molar mass of hydrogen,
`H_2 = 2* 1 = 2 g/mol`

Substituting the values:

Number of moles of hydrogen =
`(1.5)/(2) = 0.75 mol`

Number of moles of water formed on reacting with
`0.75 mol` of hydrogen is:

Number of moles of water =
`0.75 mol`

Mass of water can be calculated by:

Number of moles of water =
`(mass of water)/(Molar Mass of water)`

Molar mass of water =
`2* 1+16 = 18 g/mol`

Substituting the values:

`0.75 mol = (mass of water)/(18 g/mol)`

`mass of water = 13.5 g`

Hence, the mass of water vapor forms is
`13.5 g`.