# AP Chemistry/Constants and Equations

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## Don't Need to Memorize[edit]

- D = density = M/V
- m = mass, molality
- M = Molar mass, molarity
- n = number of moles
- P = pressure
- T = temperature
- t = time
- V = volume

## Need to Memorize[edit]

- Avogadro's number = 6.02 * 10^23
- R = ideal gas constant = 0.0821 L•atm/K•mol
- PV = nRT (Ideal gas equation)
- 1 atm = 760 torr = 760 mm Hg
- STP = 273K and 1 atm (100kPa)
- 1 cal = 4.184 J = energy needed to warm 1 g (1 mL) of water by 1K.