Question

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 1

beginning volume and ending quantity of gas

Step-by-step explanation:

Answer 2

Answer and Explanation:

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

`pV=nRT\`

`n=(pV)/(RT)`

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

`(n_1)/(n_2)=((p_1V_1)/(RT_1))/((p_2V_2)/(RT_2))`

The statement defines that

`T_1=T_2,~p_1=p_2.`

Therefore

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

`(n_1)/(3.8*10^(-4))=(230)/(860)\iff\\\\ n_1=(3.8*10^(-4)*230)/(860)`

`\boxed{n_1\approx1.0*10^(-4)~mol}`

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