Question

Calculate the weight of glucose required to prepare 500ml of 0.1M solution?

Answer 1

Molar mass of glucose = 180.16 g/mol 

This means that 1 mole of glucose = 180.16 g. 

A 1M solution contains 1 mole per litre, that is, for glucose, 180.16 g per litre. 

So, 1M glucose = 180.16 g/L 

You only need 0.5M, so you divide the number of grams by 2. 

(Half the amount of solute in 1 litre gives you half the molarity) 

Therefore, 0.5M = 180.16 / 2 = 90.08 g/L 

So you now have a 0.5M solution which has 90.08 grams glucose in 1 litre, 

but you only need half a litre (500 mL). 

Half a litre will contain half the quantity of glucose, which is 90.08/2 = 45.04 g. 

So, to make 500 mL of a 0.5M solution of glucose, you add 45.04 g glucose 

to a flask and make up the rest of the volume to a total of 500 ml with water. 

This is the definition of molarity in that it is the number of moles of solute 

Answer 2

Answer:

Molar mass of glucose = 180.16 g/mol 

This means that 1 mole of glucose = 180.16 g. 

A 1M solution contains 1 mole per litre, that is, for glucose, 180.16 g per litre. 

So, 1M glucose = 180.16 g/L 

You only need 0.5M, so you divide the number of grams by 2. 

(Half the amount of solute in 1 litre gives you half the molarity) 

Therefore, 0.5M = 180.16 / 2 = 90.08 g/L 

So you now have a 0.5M solution which has 90.08 grams glucose in 1 litre, 

but you only need half a litre (500 mL). 

Half a litre will contain half the quantity of glucose, which is 90.08/2 = 45.04 g. 

So, to make 500 mL of a 0.5M solution of glucose, you add 45.04 g glucose 

to a flask and make up the rest of the volume to a total of 500 ml with water. 

This is the definition of molarity in that it is the number of moles of solute