A balloon containing helium gas expands from 230
mL to 860 mL as more helium is added. What was
the initial quantity of helium present if the
expanded balloon contains 3.8 x 10-4 mol,
assuming constant temperature and pressure?
Which of the variables are known?
DONE

The answer for the following problem is mentioned below.

Explanation:

Given:

Initial volume () = 230 ml

Final volume () = 860 ml

Initial moles () = 3.8 × moles

To find:

Final moles ()

We know;

According to the ideal gas equation;

    P × V = n × R × T

where;

P represents the pressure of the gas

V represents the volume of the gas

n represents the no of the moles of the gas

R represents the universal gas constant

T represents the temperature of the gas

So;

    V ∝ n

=

where,

() represents the initial volume of the gas

() represents the final volume of the gas

() represents the initial  moles of the gas

() represents the final moles of the gas

Substituting the above values;

    =

  = 14.2 × moles

Therefore the final  moles of the gas is 14.2 × moles.