Introduction to Solutions (Chapter 5)

7 SCIENCE

How do solutions relate to matter?• These chemical compounds

cannot be separated by physical processes like squeezing, filtering etc

• If a substance can be broken down by physical processes it is called a mixture

• Atoms make up all matter on earth; therefore solutions are made from atoms

• When atoms combine they are called chemical compounds– Ex: What atoms make up the

chemical compound water?

Mixtures

• A mixture is a combination of substances that can be separated by physical means – Ex: boiling saltwater to separate the salt from the

water

• Two types of mixtures:– Heterogeneous– Homogeneous

Heterogeneous Mixtures

• Hetero = different• The substances in a heterogeneous mixture are

not mixed evenly, so different parts have different compositions

• Different parts of the mixture are easy to see– Ex: watermelon and seeds– Ex: oil in water

Homogeneous Mixtures

• Homo = same • Made up of 2 or more substances and one appears to

‘disappear’ into the other

• Not easy to see the different parts– Ex: Saltwater – you cannot see the salt as different than

the water– Ex: Nestea powder into water

cannot see the powder is different

• Also called a solution

Solutions • When you mix 2 or more substances together,

the substance that seems to disappear (dissolves), is called the solute

• The substance that dissolves the solute is called the solvent– Ex: Sugar and coffee– Which is the solute? Solvent?

Mixtures activityInstructions: You will travel to each mixture station and be responsible for creating a mixture with your group, record observations and answer questions individually

1) Read and follow the instructions from Ms.Young and create a hypothesis for each substance.

2) Test your hypothesis by creating a mixture at each station with 100mL of water and half a teaspoon of each substance.

3) Stir until there is no change in the mixture.

4) Record observations for each substance.

5) Please answer the following questions on the back of your observation paper:a. Which substances dissolved into the water when you stirred?b. For the substance(s) that dissolved, how do you know that it is still there? How

could you figure this out?c. Do you think the ability of water to dissolve many substances is useful in our lives?

Explain why/why not.