Unit 8 Solutions

What is a mixture? A Mixture is defined as a combination of two or more substances. The substances in a mixture can all be solids, like the mystery mixture, all liquids like salad dressing, all gasses, like the air, or combinations of solids liquids and gasses. A mixture is simply a combination of two or more substances

Write this in your notebook!

Today we are going to make two different mixtures by combining solid substances and a liquid substance. The solid substances are calcium carbonate and sodium chloride. The liquid substance is water.

Notebooks Look at the two powders and write your observations in your notebook Write down what each mixture looks like. What happened when you made a mixture of calcium carbonate and water? What happened when you made a mixture of sodium chloride and water?

Write this in your notebook!

Separate the mixture How can we separate the two mixtures? What methods can we use to separate the calcium carbonate/water mixture into its two substances? What methods can we use to separate the saltwater solution into its two substances?

Section 7 Review Vocabulary Dissolving Melting Evaporate Freeze Condense Freezing point – melting point Equilibrium

Results Were you able to separate the two mixtures? What happened when you tried to separate the sodium chloride from the water in the salt solution? Why do you think the filter paper seperated the calcium carbonate from the water but not the sodium chloride? How might we separate the sodium chloride and water? What happens during evaporation? 3241

Prepare Wells for evaporation Place 10 drops of each sample into just the well reserved for you class. Record in you notebook the time and date that the evaporation started. Predict when all the water will be gone. Clean and rinse the cups and pipettes well.

Summary (answer in workbook) Were you able to separate the two mixtures? What happened when you tried to separate the sodium chloride from the water in the salt solution? Why do you think the filter paper separated the calcium carbonate from the water? How can we separate the sodium chloride and water? What happens during evaporation?

Write in Your Notebook Saturated Solution  A solution in which the maximum amount of solute has been dissolved. Any more solute added will sit as crystals on the bottom of the container.

Observe the wells Did the water in wells 1 and 2 evaporate? What was left in the wells? Did the water in wells 5 and 6 evaporate? What was left in the wells? Did the water in wells 9 and 10 evaporate? What was left? Were you able to separate the two mixtures? How?

Part 2 Does sodium chloride dissolve in water? How do you know? What happens at the particle level when sodium chloride dissolves? In Part 1 you added 2-ml spoon of salt to 30 g of water. The salt dissolved. What do you think would happen if you added another 2 mL spoon of salt. Would it dissolve ?

Read How things Dissolve

Saturation Lab Is there a limit to the amount of a substance that will dissolve in a measure of water? If so, is the amount of a substance that will dissolve in a measure of water the same for all substances? What could you do to find out the answers to these questions? Discuss in your groups and write down a plan.

Two saturated solutions sodium chloride and magnesium sulfate were made. Which saturated solution had more solute dissolved in it? How much magnesium sulfate was needed to saturate 30mL of water?

Solution #1 is made with 200 mL of water and 20 g of magnesium sulfate Solution #2 is made with the same amount of water and 50 g of magnesium sulfate. How are the two solutions the same and how are they different?

Concentration Concentration is the ratio between the amount of solute and the amount of solvent in a solution. The more solute there is dissolved in a volume of solvent, the more concentrated the solution. Is Solution #1 or #2 more concentrated?

If I weigh a 40 mL sample of each of these two solutions, will the masses of the two be equal or will one weigh more than the other? Today each group will make their own solution with magnesium sulfate and water. After the solutions are made we will investigate them to see if we can figure out which solution is the most concentrated.

Concentration Solute / total Solution Order of Concentration

Mass of 20ml Concentration

Which of the solutions is most concentrated? How can we find out?