# Question #e4692

May 29, 2017

2.675 grams of Helium.

#### Explanation:

995 torr equals 1.309 atm (P).
T is $173.15 + 25 = 298.15$ K
Now we can use this formula (The ideal gas law)

$P \cdot V = n \cdot R \cdot T$

$1.309 \cdot 12.5 = n \cdot 0.082056 \cdot 298.15$

$n = 0.6688$ moles of Helium.

Since Helium has a mass of 4 g/mol, you can compute

$M a s s = 0.6688 \cdot 4$

$M a s s = 2.675$ grams of Helium.