Question

If 0.42 mole of helium occupies 9.9 L, how

many moles must be added to inflate the
balloon to 17.0 L?

Answer 1

0.301 moles

Further explanation

Avogadro's hypothesis:

In the same T,P and V, the gas contains the same number of molecules

So the ratio of gas volume will be equal to the ratio of gas moles

Given

n₁=initial mol of Helium : 0.42

V₁=initial volume : 9.9 L

V₂=final volume : 17 L

Required

number of moles added

Analysis

Use formula :

`\tt (V_1)/(n_1)=(V_2)/(n_2)`

Solution

`\tt n_2=(n_1* V_2)/(V_1)\\\\n_2=(0.42* 17)/(9.9)\\\\n_2=0.721~moles`

moles added :

0.721 - 0.42 =0.301 moles

Paraphrase

0.301 moles must be added to inflate the balloon to 17.0 L