# Question e8863

Nov 19, 2015

The volume of 0.00988 moles of Oxygen @ STP = 224.5 ml

#### Explanation:

Since the condition is at STP, therefore the value of P = 0.98692 atm, T= 273.15 K and the R = 0.0821 li- atm/mole-K. The no. of moles of Oxygen is given as 0.00988 moles.

Using the Ideal Gas Law:

PV = nRT , divide both sides by P to isolate the V
V = nRT/P, the desired formula, then substitute the given data
V = {0.00988$\cancel{m o l}$}{0.0821 li-$\cancel{a t m}$/($\cancel{m o l}$-$\cancel{K}$}{273.15$\cancel{K}$}/{0.98692$\cancel{a t m}$}
V = 0.2215519 li/0.98692
V = 0.2244882 li, convert to ml
V = 224.5 ml, the volume of 0.00988 moles of Oxygen at STP

Nov 20, 2015

The volume of oxygen gas is $\text{224 mL}$.

#### Explanation:

$\text{STP}$ is $\text{273.15 K}$ and $\text{100 kPa}$.

Use the ideal gas law to answer this question. The equation for the ideal gas law is $\text{PV=nRT}$.

Given/Known
$P = \text{100 kPa}$
$T = \text{273.15 K}$
$n = \text{0.00988 mol}$
$R = \text{8.3144598 L kPa K"^(-1) "mol"^(-1)}$

Unknown
Volume in mL

Solution
Rearrange the equation to isolate $V$ and solve. Then multiply the volume in liters times 1000 to get mL.

$V = \frac{n R T}{P}$

V=((0.00988cancel"mol")xx(8.3144598"L" cancel"kPa" cancel("K"^(-1)) cancel("mol"^(-1)))xx(273.15cancel"K"))/(100cancel"kPa")="0.224 L"#

Convert 0.224 L to mL

$0.224 \text{L"xx(1000"mL")/(1"L")="224 mL}$