weight to mol percent

how to convert 15 mole percent of styrene (MW=104 g/mol) to weight percent, if we know the other monomer M (MW= 54 g/mol) is 85 mole % in the polymer?
Is this info enough or dowe need more data to get the conversion?

[JohnS]

Originally Posted by www

how to convert 15 mole percent of styrene (MW=104 g/mol) to weight percent, if we know the other monomer M (MW= 54 g/mol) is 85 mole % in the polymer?
Is this info enough or dowe need more data to get the conversion?

Imagine that you have 100 moles total mixture, 15 moles styrene, 85 moles of the other monomer.

The weights of the mixture components are 15 moles*104 g/mol = 1560 g styrene, and 85 moles * 54 g/mole = 4590 g of the other monomer.


The total mixture is 1560 g + 4590 g = 6150 g,
and the weight ratio of styrene to total mixture is
1560 g/6150 g = 25.4%

Since we postulated 100 moles, and total weight is 6150 g, the average molar mass of the mixture is 61.5 g/mol, and you can get the same answer as
15% * 104 g/mol / 61.5 g/mol (this "average" approach is often used for pollutants mixed in air)

John thanks a lot for the explanation. It seems very simple now.

5mol percent of 6.26grm of Bi2O3

Originally Posted by Unregistered

5mol percent of 6.26grm of Bi2O3

I want to know how to calculate 10 mol % of CuO

I want to know how to calculate 10 mol % of para toluene sulphonic acid

the mole%of sodium hydroxide weight of 100gm.

[JohnS]

Originally Posted by Unregistered

the mole%of sodium hydroxide weight of 100gm.

Approximate molar mass is (23 + 16 + 1) g/mol or 40 g/mol
100 g is about 2.5 mol. No percent involved.

If it is pure sodium hydroxide then it is 100% sodium hydroxide whether by weight, volume, or molar ratios. Percent and parts per million are for mixtures of one thing in another thing.

What if I am given a molar flow rate (300mol/h) for a gas stream but am given %wt percents for each species in the stream? How can these be converted to mol%?

[JohnS]

Originally Posted by Unregistered

What if I am given a molar flow rate (300mol/h) for a gas stream but am given %wt percents for each species in the stream? How can these be converted to mol%?

First, are you sure they are weight percents? Gases are usually specified by molar percents or partial pressures (the same if you assume ideal gas law).

If they are percent by weight, divide by the molecular weight of the species and multiply by the (average) molecular weight of the mixture.