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 × 10-4 mol, assuming constant temperature and pressure? Which of the variables are known?

Answer :

Answer and Explanation:

For computing the initial quantity of helium we have to apply the law of ideal gas which is shown below:

[tex]pV=nRT\[/tex]

[tex]n=\dfrac{pV}{RT}[/tex]

Now we have to compute the ratio between the initial and the final numbers of moles which is

[tex]\dfrac{n_1}{n_2}=\dfrac{\dfrac{p_1V_1}{RT_1}}{\dfrac{p_2V_2}{RT_2}}[/tex]

The statement defines that

[tex]T_1=T_2,~p_1=p_2.[/tex]

Therefore

[tex]\dfrac{n_1}{n_2}=\dfrac{V_1}{V_2}[/tex]

[tex]\dfrac{n_1}{3.8\times10^{-4}}=\dfrac{230}{860}\iff\\\\ n_1=\dfrac{3.8\times10^{-4}\times230}{860}[/tex]

[tex]\boxed{n_1\approx1.0\times10^{-4}~mol}[/tex]

And, the variables are known is starting volume and ending gas quantity

Answer:

beginning volume and ending quantity of gas

Explanation:

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