Question

2Na + 2H2O → 2NaOH+ H2
How many grams of hydrogen are produced if 120 g of Na are available? (show your work using factor-label method)

Answer 1

Answer:

2.6 gm

Explanation:

46 gm of Na required to produce 1 gm of H2

1 gm of Na required to produce 1/46 gm of H2

therefore

if 120 gm of Na available then , Hydrogen produce in amount =1/46 ×120 gm

=2.6 gm

Answer 2

120 g of sodium will result in the formation of 5.21 g of hydrogen gas.

Explanation:

Given:

• A reaction between sodium metal and water to produce sodium hydroxide and hydrogen gas, $2Na + 2H_2O \rightarrow 2NaOH+ H_2$
• Mass of Na = 120 g

To find: Mass of hydrogen gas formed

Solution:

• Using the balanced chemical equation $2Na + 2H_2O \rightarrow 2NaOH+ H_2$, we can conclude that

2 moles of sodium would produce one mole of hydrogen gas

• Mass of 1 mole of sodium = molar mass of sodium =  23 g
• Mass of 1 mole of hydrogen = molar mass of hydrogen =  2 g

Hence,

• 2 x 23 g of Na will produce =  2 g of $H_2$

Using the unitary method,

• 1 g of Na will produce $= \frac{2}{46}$ g of $H_2$

• 120 g of Na will produce $= \frac{2}{46}\times 120$ g of $H_2$ = 5.21 g of $H_2$

Hence, 120 g of sodium will result in the formation of 5.21 g of hydrogen gas.