Question

20 L of H2 gas at STP weigh about
1) 44.8 g
2) 12.2 g
3) 1.8 g
4) 20 g
with step by step explanation

Answer 1

Answer: 20 L H2 gas will weigh

 =( 20/22.4)*2

 =1.8182

 =1.8 g

Explanation:The H2 gas weights 2 g (approx) in 22.4L where there is Avagadro no of molecules present in it . Therefore the gas will weight about 1.8 g  (approximately)

If you want to study the mole concept and stoichiometry  then I prefer Khan Academy lessons which is available on Youtube as well as in their website.

All the very best for your studies.

Answer 2

Answer:

20 L of H₂ gas at STP has weigh about 1.8g.

Explanation:

As we know that,

22.4 Liters H₂ gas has weight at STP $= 2g$

Weight of  1 L of H₂ gas $=\frac{2}{22.4}gL^{-1}$

Weight of 20 L of H₂ gas at STP $=20*0.089=1.78g$ ≈ $1.8g$

Therefore the option 3 is correct.