Thursday, September 18, 2014

Units 1

Units are very important in chemistry as we often have to do conversions.

Mole- This is the SI unit for amount of substance.

Avogadro no  = 6.023 *10^23 mol ^-1

Unit of force - newton N

1 N = 1 kgms^-2
as per my experience units expressed in terms of simple ' kg - m - s ' are very important for deriving equations.

Pressure is force applied per area
Pascal is the unit used for measuring pressure.

1 Pa = 1 Nm^-2 = 1 kgm^-1s^-2

Energy is measured in terms of joule

1 J = 1 Nm = 1 kgm^2s^-2

calorie ( cal) = the amount of heat required to raise temp of 1g of water by 1 degree C

1 cal = 4.184 J
1 atm= 101,325 Pa
760 torr = 1 atm
1 bar= 750 torr

bar stands for barometer which is the unit for measuring pressure.
average barometric pressure near sea level is approx 1 atm.


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