Relationship Between No. Of Moles And Mass

CHAPTER 3 : CHEMICAL FORMULAE & EQUATIONS 3.3 The Mole & the Mass of Substances

3.3 The Mole & the Mass of Substances

At the end of this lesson you should be able to:

1. State the meaning of molar mass 2. Relate molar mass to the NA 3. Relate molar mass of a substance to its Ar and Mr 4. Solve numerical problems to convert the number of moles of a given substance to its mass and vice versa

MOLAR MASS

The mass of 1 mol of a substance

Relative mass (Ar or Mr) of a substance

The mass of NA (6.02 x 1023 particles) • unit of molar mass: grams per mole or g mol-1

State the relative mass and the molar masses these substances:  Na  H2O  ZnCl2  CuSO4 Ar: Na,23; H,1; O,16; Zn,65; Cl2,35.5; Cu,64; S,32

Relationship between the number of moles and the mass of a substance x molar mass

No. of Moles

Mass (g) molar mass

No. of moles

=

Mass (g) Molar mass (Ar or Mr)