Question

13.What volume of hydrogen gas is produced when 92.4 g of sodium reacts completely according to the following reaction at 25 °C and 1 atm?

sodium (s) + water(l)------->sodium hydroxide (aq) + hydrogen(g)

Answer 1

44.8L of hydrogen gas

Step-by-step explanation:

The reaction expression is given as:

2Na + 2H₂O → 2NaOH + H₂

Given parameters:

Mass of sodium = 92.4g

Unknown:

Volume of hydrogen gas = ?

Solution:

To solve this problem:

1 mole of a substance at STP occupies a volume of 22.4L

Let us find the number of moles of the hydrogen gas;

Number of moles of Na =
`(mass)/(molar mass)`

Molar mass of Na = 23g/mol

Number of moles =
`(92.4)/(23)` = 4.02mole

From the balanced reaction expression:

2 mole of Na will produce 1 mole of hydrogen gas

4.02 mole of Na will produce
`(4.02)/(2)` = 2mole of hydrogen gas

So

1 mole of a substance at STP occupies a volume of 22.4L

2 mole of hydrogen gas will occupy a volume of 2 x 22.4 = 44.8L of hydrogen gas