Stoichiometry

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• $x$ mols of a substance reacts with $x$ mols of another substance to create $x$ mols of a product
• If one reactant has more moles than another (i.e. is in excess, and some moles are not involved in the reaction), the reactant with the lowest number of moles is the limiting reagent, and thus only that amount of moles will react
• For example: $kX+mY\to nZ$
• $k$ moles of $X$ will react with $m$ moles of $Y$ to produce $n$ moles of $Z$
• Here, if the number of moles of $X$ exceeds $k$, only $k$ moles will react, and $mY$ would be the limiting reagent (assuming $m$ is constant)

Moles (not gas)

$n=\frac{m}{M}$

• $n=$ number of moles
• $m=$ mass (g)
• $M=$ Molar Mass (g per mol)
• Note: this is only for solids, aqueous solutions, and liquids

Moles for Ideal Gases

$n=\frac{V}{22.71}$

• $n=$ number of moles
• $V=$ volume (L)
• This is for standard temperature and pressure ($0˚C=273.15K$, $100kPa$)
• Always assume standard conditions, unless stated otherwise

$PV=nRT$

• $n=$ number of moles
• $P=$ pressure (kPa)
• $V=$ volume (L)
• $T=$ temperature (k)
• $R=$ universal gas constant, $8.314J{K}^{-1}mo{l}^{-1}$