Formulas

Formulas

1. Important Symbols and Constants

Symbol	Meaning
$R$	Gas constant
$n$	Number of moles
$m$	Mass
$T$	Temperature
$V$	Volume
$c$	Concentration

2. Essential Chemical Equations

Mole Calculations

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

Where:

• $n =$ Number of moles
• $m =$ Mass $(g)$
• $M =$ Molar mass $(g·mol⁻¹)$ $c = \frac{n}{V}$

Where:

• $c =$ Concentration $(mol·dm⁻³)$
• $V =$ Volume $(dm³)$ $c = \frac{m}{MV}$

Where:

• $MV =$ Molar volume $(dm³·mol⁻¹)$

Ideal Gas Law

$PV = nRT$

Where:

• $P =$ Pressure $(Pa)$
• $V =$ Volume $(m³)$
• $n =$ Number of moles
• $R =$ Gas constant $(8.31 J·mol⁻¹·K⁻¹)$
• $T =$ Temperature $(K)$

Chemical Equilibrium Expression

For a reaction:

$2P + 3R \rightleftharpoons 25 + 4T$

The equilibrium constant $(Kₑ)$ is given by:

$K_c = \frac{[S]^{x} [T]^{y}}{[P]^{z} [R]^{w}}$

Where [ ] represents the concentration of each substance in $mol·dm⁻³$.

3. Key Notes

• Subscripts in chemical formulas show the number of atoms (e.g. H₂O means 2 hydrogen atoms and 1 oxygen atom).
• Balanced equations are necessary when using stoichiometric calculations.