Lesson 3.3 Separating Solutions

The clear water you produced in the last part of Lesson 3 still contained many dissolved solutes.  They are not visible, but neither is the salt in saltwater visible.  Is there a way to separate the salt from the water in a saltwater solution?  This next investigation will show one of the ways it can be done. 

Read pages 52 and 53 to learn how you could separate the salt from a saltwater solution.

Prepare a salt-water solution by adding a spoonful of salt to 50 mL of water in a small pot.  Look at the solution and record any observations such as colour.  Heat the salt solution with low heat on your stove.  When all the water has evaporated, remove the pot from the stove, let it cool, and look at the residue and record any observations.

Based on your observations answer the following questions.

Question 1. Describe the appearance of the salt before adding it to the water.

Question 2. Describe the appearance of the saltwater solution.

Question 3. What happened to the water in the solution as the solution was heated?

Question 4. Describe the appearance of the substance left in the pot.

Question 5. What is the substance that is left in the pot?

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. Describe the appearance of the salt.

The salt is a white, grainy, solid.

Question 2. Describe the appearance of the saltwater solution.

The saltwater solution is a clear, colourless solution.  It looks the same as water.

Question 3. What happened to the water in the solution as the solution was heated?

The water evaporated.

Question 4. Describe the appearance of the substance left in the pot.

The substance left in the pot looks the same as the original salt except that it is not as grainy.

Question 5. What is the substance that is left in the pot?

The substance left in the pot is salt.


Click on the page forward to continue Lesson 3.