# Gases
+## Comibned gas equation
+
+$${P_1 V_1 \over T_1} = {P_2 V_2 \over T_2}$$
+
## Perfect gas equation
$$PV=nRT$$
-where $R =$ universal gas constant $= 8.31 \text{J} \text{K}^{-1} \text{mol}^{-1}$
-$P$ is measured in kPa
-$V$ is measured in L
-$T$ is measured in K
+where
+$R =$ universal gas constant $= 8.31 \text{ J K}^{-1} \text{mol}^{-1}$
+$P$ is measured in kPa
+$V$ is measured in L
+$T$ is measured in K
$n$ is no of mol of gas
> Equal volumes of all gases measured at the same temperature and pressure contain the same number of gas particles
-$\therefore$ 1 mole of any gas at SLC occupies 24.8L - **molar gas voluem**
+$\therefore$ 1 mole of any gas at SLC occupies 24.8L - **molar gas volume**
$$n={V \over V_M}$$
$V_m$ = molar volume of gas
$$\therefore n_{SLC} = {V \over 24.8}$$
+
+## Molar volume
+
+Volume of a mole of a gas - depends on pressure & temperature
+Molar gas volume = $V_M = 24.8 \text{ L mol}^{-1}$ at SLC
+Use $n = {V \over V_m}$ like $n={m \over M}$
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