Chapter 1 Answers

Lesson 1 Answers

1. Farming 150 years ago consisted of animal and manual labour to plant, grow, and maintain crops, gardens, and livestock. The technological advances farmers use today include automatic feeders, barn cleaners, and modern tractors with tillage equipment to do the work.

2. Farmers 150 years ago pulled weeds in fields and picked insects of f crops in gardens. The chemical advances that have changed farming today are the use of chemical pesticides to kill unwanted plants and insects and the use of fertilizers to produce larger crop yields.

3. Chemical and technological advances have provided 

   • increased food production 

   • more appealing fruit and vegetables •

   • food with a longer shelf life

4. Manufactured fertilizers are more effective than natural fertilizers because they are designed for specific crops and soil conditions.

5. Natural fertilizers provide organic matter to the soil. 6. 

6. A pesticide like Dursban must be handled with care because it can damage the brain and central nervous system if inhaled or ingested. 

7. Farmers can learn about the precautions required when handling pesticides by carefully reading the labels on the product and any literature that accompanies the product. 

8. Over the past 100 years soaps have been improved by adding ingredients that make them smell nice, produce more suds, and help soften skin. 

9. Soap consists of two-ended molecules that allow one end to dissolve in grease while the other end dissolves in water. This allows water to wash away any grease. 

10. The soap feels similar to soaps of today; it is slippery and produces lather. It does not, however, lather as well as today’s soaps. Also, the soap does not have a nice fragrance; but, then again, no fragrances were added. 

11. Answers will vary. Although soap making is a large commercial industry with dozens of brands on the market, soap making is also a popular, home-based business. At one time, various types of animal fat were used to make soap. Today, many varieties of ingredients are used: goats milk, glycerine, coconut oil, vegetable oils, and oatmeal to name a few. Various natural fragrances are used to scent the soaps. Soap-making 100 years ago often used stove ashes as the base in place of lye (caustic soda). Today, you can buy ready-made bases, where you only need to melt and add softening or fragrance ingredients. 

12. Sports items made from synthetic materials include 

    • hockey jerseys (polyesters) 

    • canoes (Kevlar) 

    • tents (nylon) netting for basketball hoops (nylon) 

    • waterproof and windproof jackets (Gore-Tex) 

13. Polyester is a good material for sports clothing because it does not absorb moisture and it retains its shape.

Lesson 1.4 Answers

1. Automotive repair shops, hair salons, offices, and construction sites are four areas of work where a working knowledge of chemistry is needed. 

2. Chemicals in paints, fillers, and cleaners are used in an automotive repair shop to fix and paint damaged car bodies. 

3. In a hair salon chemicals are used in colourants, curling solutions, shampoos, and conditioners. 

4. Before 1938, hair stylists removed soap scum from hair by rinsing it with an acid solution made up of vinegar or lemon juice. 

5. Shampoos add texture to your hair by coating each hair strand with plastic resins. 6. Deter gents have a pH of about 10.5, according to the pH scale on page 16 of the textbook. 

7. The manipulated variable is the brand of dish detergent. The responding variable is how clean the plastic glass gets. 

8. The amount of dish detergent used for each washing and the temperature of the wash water are variables that must be controlled.