Student Reader

Measurement

Units of Mass

Atomic Mass Unit1 u = 1.6605 × 10-27
Mole (mol)

One mole is defined as the amount of substance that contains exactly as many atoms or molecules as are in precisely 12 grams of 12C.

units in moles = mass ( grams ) / molecular mass ( g mol-1 )

Units of Temperature

Celsius/Centigrade (C)

Absolute zero: -273.15°C
Water freezes: 0°C
Water boils: 100°C

T°C = 59 ( T°F - 32 )

Fahrenheit (F)

Absolute zero: -459.67°F
Water freezes: 32°F
Water boils: 212°F

T°F = 95 T°C + 32

Kelvin (K)

Kelvin and Centigrade have equal increments. The difference between Kelvin and Centigrade is that 0°K is absolute zero (-273.15°C) and 0°C is the freezing point of water (273.15°K). Thus, ΔT in °K and °C will be equal, even though T°F ≠ T°C.

Absolute zero: 0°K
Water freezes: 273.15°K
Water boils: 373.15°K

Units of Pressure

Pascals (Pa)N/m2 1 Pascal = 7.50247 · 10-3 mm-Hg 1 Pascal = 9.86923 · 10-6 atm 1 Pascal = 10-5 Bar 1 Pascal = 1.45037738 · 10-4 PSI
Torrmm-Hg 1 Torr = 133.289437 Pascal
Atm 1 atm = 1.01325 · 105 Pascal 1 atm = 760.0 mm-Hg
Bar 1 Bar = 105 Pascal
PSIlbs in-2 1 PSI = 6894.75729 Pascal

Units of Heat and Energy

Joule (J)
calorie (cal)1 calorie = 4.186 J
Calorie (Cal)1 Calorie = 4.186 kJ = 1000 cal = 1 kcal = 4186 J
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