Question

How to convert molecular weight from $ g/mol $ to $ lb/mol $ ?

Answer 1

Hint: To solve this question, we need to use the relation between one pound and one kilogram, and the relation between one kilogram and one gram. From these two relations, we can express one gram in pounds, from which the desired conversion can be formulated.

Complete step-by-step solution
The unit $ lb $ stands for a pound. It is an imperial unit and is used in the United states. We know that one pound is equal to nearly $ 0.45 $ kilograms. So we can write
 $ 1lb = 0.45kg $
Dividing by $ 0.45 $ both the sides, we get
 $ 1kg = \dfrac{1}{{0.45}}lb $
On simplifying the above equation, we get
 $ 1kg = 2.2lb $ ....................(1)
Now, we also know that one kilogram is equal to one thousand grams. So we can write that
 $ 1kg = 1000g $
Substituting one kilogram in terms of pounds from (1) in the above equation, we get
 $ 2.2lb = 1000g $
Dividing by $ 1000 $ on both the sides, we get
 $ 1g = \dfrac{{2.2}}{{1000}}lb $
On simplifying and writing in terms of the scientific notation, we get
 $ 1g = 2.2 \times {10^{ - 3}}lb $
For getting the relation between units of the molecular weight, we divide both of the sides of the above equation by one mole to get
 $ 1g/mol = 2.2 \times {10^{ - 3}}lb/mol $
Hence, for converting the molecular weight from one gram per mole to one pound per mole, we have to multiply the molecular weight given in gram per mole with $ 2.2 \times {10^{ - 3}} $ .

Note:
The unit of the weight, Pound, is used in the imperial, United states customary and the other measurement systems. It has been descended from the Roman Libra, and hence the unit is abbreviated as lb. One use of this unit includes in the measurement of the weight of the smoothbore cannon and carronades.