Understanding Solutions

Solutions consist of solvents and solutes:

The solvent is part of the solution that makes up the biggest part.

The solute is present in the smallest part and is dissolved by the solvent.

QUESTION: In sugar water, what is the solvent and what is the solute?

Answer: Water is the solvent and sugar is the solute

A solution has the same properties throughout. It contains solute particles that are too small to see.

Water is called the “universal Solvent” because it dissolves so many other substances.

Water is the solvent in blood, sweat, tears, and the soil

Question: Can a solution only be made with liquid solvents?

Answer: No, solutions can be made with other solvents. Any combination of gases, liquids, and solids can make up solutions.

A colloid is a mixture containing small, un-dissolved particles that do not settle out.

A colloid contains larger particles than a solution.

Question: Which of the following are examples of colloids?a. fog b. Salt water

c. milk d. Snow globe

Answer:

a. Fogb. milk

A suspension is a mixture in which particles can be seen and easily separated by settling or filtration.

Question: How does a suspension differ from a solution?

Answer: A solution has same properties throughout and a suspension does not. A suspension contains visible particles that will settle out - they are larger than the particles in a solution.

Pepper and water is an example of a suspension

When an ionic solid mixes with water, the positive and negative ions are attracted to the polar water molecules.

An ion is a group of atoms with an electric charge. When an atom loses an electron, it becomes a positive ion.

Question: What happens when an atom gains an electron?

Answer: It gains a negative charge and becomes a negative ion.

Whenever a solution forms, the particles of the solute leave each other and become surrounded by particles of the solvent.

A solution of ionic compounds in water conducts electricity such as in salt water. Solutions such as sugar water have no ions and will not have conductivity.

Solutes lower the freezing point and raise the boiling point of a solvent.

This is the reason that antifreeze mixed with water in a car’s engine help to keep a car’s engine from overheating or freezing up.

Solute LABProblem: How is the temperature of

water affected by salt being added to it?

Hypothesis: When salt is added to water, then the temperature of the water _____________.

Materials:glass beaker salt50 milliliters of water teaspoonthermometer paper and

pencil

Procedure: 1. Place 150ml of water into a clear beaker.2. Take the temperature using thermometer

and write on your chart.3. Add 1 teaspoon of salt and stir thoroughly.

Wait five minutes and take temperature. Write on your chart

4. Continue steps above until 4 teaspoons have been added.

Salt Water Temperature Salt Content Temperature

No salt added _______________°Celsius

1 teaspoon _______________°Celsius

2 teaspoons _______________°Celsius

3 teaspoons _______________°Celsius

4 teaspoons _______________°Celsius

Solute Lab (cont’d)

Write a one paragraph summary about the findings of your lab. Also write how this lab relates to adding rock salt to our bags when we made ice cream.