Separating mixtures in chemistry lab (PLEASE HELP. URGENT!)

Question

You are to separate the two components of a mixture of sand and sugar. The initial mass of the mixture is 32.4563g. You found that the mass of sand was 19.5642g. 

 

A) Describe the procedure you would have to follow to determine the mass of the sand. 

 

B) Upon heating the sugar solution, it was found that the sugar turned to a black gooey mess. How will you determine the mass of the sugar?

 

C) Calculate the percent composition of the original sample.  

Answer 1

Hello Alex,

 

If you look at the whole question, a clue to the answer to part A is given in part B: "the sugar solution" implies that the sugar was dissolved in something, almost certainly water. Sand, of course, is not soluble in water, so that gives you a method of getting the sugar away from the sand (don't forget to dry the sand before you weigh it).

 

The real answer to part B is not "get rid of the water from the sugar solution," but instead you should apply the Law of Conservation of Mass. Since the original mixture was just sugar and sand, and you know how much of the mixture you had and how much sand was in it, a quick subtraction will give you how much must have been sugar.

 

Percent composition is a simple calculation:

 

% of a component = (mass of component)/(total mass)×100

 

Use that formula for the sugar and the sand, and you have the percent composition for the mixture.

 

Jim Scripko