Unit A

Matter and Chemical Change

Science 24

The MRE (Meal, Ready-to-Eat)

- In 1992, the United States Department of Defense developed a flameless ration heater that would allow soldiers to have a fully-cooked hot meal available in a small, light package- To cook the meal, water is added to a small amount of magnesium metal and salt in order to produce heat

What evidence of chemical reactions would you see if you were to use an MRE? What kind of changes would take place?Prior to the 1990s, how would the cooking of these meals have been different?

Chapter 1 - Useful Chemistry

What You Will Learn Skills You Will Use

How new materials have changed everyday life over the last 100 years.

Investigate how modern chemicals and processes have changed daily routines.

About some chemical changes involved in cooking, cleaning and gardening.

Investigate chemical changes involved in cooking, cleaning, gardening, and cosmetics.

About the role of chemicals in the workplace

Read and interpret HHPS and WHMIS symbols.

How to interpret safety information at work and home.

Read and interpret an MSDS.

1.1 - Chemistry Then and Now

Chemistry on the Farm

Farm practice 100 years ago

Farm practice today

- using horses to pull plows

- shovelling manure

- pulling weeds

- removing insects by hand

The Benefits of Chemical Pesticides & Fertilizers

Pesticides:

Fertilizers:

Chemistry for Cleaning

- Humans have produced soap for thousands of years- Early soap was made using ashes from stoves and fireplaces mixed with animal fat- We now use plant oils to make most soaps, and add chemicals to produce more suds or help soften skin

What are some benefits to using plant oils rather than animal fat?

How Does Soap Work?

- Most cleaners use strong bases, which react with fatty acids in the oil or fat used in the soap-This produces a two-ended molecule- One end attaches to grease particles, and the other attaches to water

Chemistry and Synthetics

Synthetic:

What are some examples of natural fibres?

What are some examples of synthetic fibres?

1.2 - Plastics, Polymers, and Alloys

Polymer:

What are some examples of natural polymers?

What are some examples of synthetic polymers?

Plastics

- Plastics are simply a certain type of polymer- Here are some common types of plastics:

Neoprene Polyethylene Polystyrene Polyurethane

rubbery, porous and insulating

can be easily formed into lightweight containers

does not absorb water or conduct electricity

flexible & fibrous, does not absorb water

Alloys

Alloy:

- Think of some examples of alloys that you have seen or used

Why Use Alloys?

- Alloys often are much stronger and lighter than using a pure metal- We can make alloys that are resistant to rust and other environmental factors- Some alloy mixtures allow steel to become more flexible, allowing it to bend or stretch

1.3 - Chemistry at Home

What are some examples of chemicals that you might use at home?

- For items sold for household use, a safety system known as HHPS is used

HHPS:

Chemistry and Cooking

- When you cook something, you are carrying out a series of chemical reactions

Here are some examples of these reactions:

1.4 - Chemistry at Work

- Blacksmiths, welders, bakers and many others have used chemistry at work for hundreds of years- Today, there are many different places where we use chemistry in the workplace

What are examples of where chemistry is used in...

- Automotive Repair Shops

- Hair Salons

- Offices

- Construction Sites

Cosmetic Chemistry

- If you use normal bar soap on your hair, it leaves it dull and rough- This is because the base in the soap breaks down the protein in your hair- The soap, along with calcium in water, also leaves a layer of scum on your hair- Hair stylists knew that removing the scum with a weak acid such as lemon juice or vinegar would make your hair shiny after washing- Modern shampoos (first made in the early 1940s) are a synthetic detergent

Make-up and Face Cream

- Cosmetics have been around for thousands of years- Some cosmetics can be toxic or have other side effects- Many cosmetics have been tested on animals to check for negative side-effects

What are some positive and negative views on animal testing?

Chemical Safety in the Workplace

- In a workplace, you should be aware of the chemicals that you work with, and the hazards associated with each of them- In Canada, two systems are in place to keep us aware of what chemicals are in the workplace, and how they should be handled

WHMIS:

MSDS:

WHMIS Symbols

The MSDS

- Although their formats may differ, all MSDS sheets have the same categories