Lesson 2.5 What Affects Solubility?

You learned that substances such as oil will not dissolve in water.  You learned that temperature affects the solubility of substances.  You know that many foods have oils and grease in them.  These oils and grease get on the dishes and utensils you use.  How does soap work to remove the oils and grease from dishes (and you and your clothes)? 

Read the section How Soap Works  on page 49 of your textbook. 

Question 1. Originally, from what two substances was soap made?

Question 2. How does soap work?

Question 3. Would clothes wash better in cold or hot water?  Hint: Think back to the investigation How Does Temperature Affect Solubility.

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. Originally, from what two substances was soap made?

Originally, soap was made from animal fat and ashes.

Question 2. How does soap work?

Soap can dissolve in both water and oil.  The soap is first dissolved in water.  The resulting solution can dissolve oils and grease.  The oils and grease on dirty clothes will now dissolve into the soapy solution and are rinsed away leaving the clothes clean.

Question 3. Would clothes wash better in cold or hot water?  Hint: Think back to the investigation How Does Temperature Affect Solubility.

Clothes will wash better in hot water because solubility is increased as temperature increases.  The problem with using hot water to wash clothes is that colours tend to fade or run, clothes may shrink, and clothes may lose some properties such as wrinkle resistance.  Many modern detergents are made to work well in cold water.


Now, do Assignment 3B.  Please page forward to access the computer-scored assignment.