This document discusses how to separate a salt solution. It describes evaporating a saltwater solution to separate out the salt. When the solution evaporates, it leaves behind salt crystals. Observing the crystals allows them to be identified by their cubic shape and sometimes X-like pattern. The mass of the salt can be determined by subtracting the mass of water alone from the total mass of the saltwater solution.

1. Focus Question:
How do you separate a salt
solution?
Mixtures and Solutions
Separating Mixtures 1-2

2. Mixtures Review
• What is a mixture? How can a mixture
be separated?
• All mixtures can be separated. We used
a metal screen and filter paper to
separate two of our mixtures.
• Salt and water make a special kind of
mixture, called a solution.

3. Separating a Salt Solution
• Can you separate a solution with a
screen? With a paper filter?
• How might you separate the ingredients
in a solution?
• Today we’ll be putting together and
taking apart salt solutions.

4. Weighing Water
• Put two empty cups on the balance and
zero the balance
• Use a syringe to add 50 ml of water to
one cup
• Add 1-gram pieces to the empty cup
until it balances again
• Count the gram pieces
• What is the mass of 50 ml of water?

5. Salt Solution
• If you put a spoon of salt in 50 ml of
water and stir until the salt dissolves,
will the solution have the same mass as
50 ml of plain water? More mass? Less
mass? (Mass is the amount of matter in
an object)
• How can you find out?
• Discuss with your group to decide how
to answer this question.

6. Determining the Mass of Salt
• Did the salt and water mixture have the
same mass as plain water? More
mass? Less mass?
• How can you determine the mass
(number of grams) of salt you put in the
water to make the solution?
• 50 ml of water = 50 gr
• Mass of the salt is the difference
between the solution mass and 50 gr.

7. Separating the Salt Solution
• Mixtures can be separated
• Separated gravel and water, and
powder and water with filters.
• How can you separate the salt from the
water? How can you get the salt back?

8. Evaporating the Salt Solution
• Set up two evaporating dishes
• Use two pieces of scratch paper to label
with room # and group #
• Place scratch paper and empty dishes
in evaporating tray
• Then pour a small amount of solution
from the cup into each dish, just enough
to cover the bottom of the dish
• Clean up. Throw out remaining solution,
rinse cups and replace all equipment in
bin.

9. Results Observations
• We set up evaporating dishes to try to
separate the salt from the water in our
saltwater solution.
• What happened when the saltwater
solution evaporated?
• What is the material in the dish?
• What happened to the water that was in
the mixture?
• Does the salt look the same as it did
originally?

10. Evaporation Results
• Use the hand lenses to help complete
Evaporation Results worksheet.
• Draw and label a picture of the crystals
in the dish.
• Zoom in on one crystal; draw and label
the crystal.
• Answer the questions on the page.

11. Crystals
• Observing sodium chloride (salt)
crystals
– A crystal is the solid form of a material that
can be identified by its properties, such as
shape, color, and pattern.
– The salt crystal looks square and
sometimes has lines corner to corner,
making an X.
• Replace dishes for use in later
investigation.

12. Separation Review
• In your group, describe how you would
separate the following mixtures:
– Gravel-and-water mixture
– Powder-and water mixture
– Salt-and-water solution
• Write your descriptions in your science
notebook.

13. Response Sheet
• Complete Response Sheet - Separating
Mixtures.
• Turn to Vocabulary when you are
finished.

14. Vocabulary
• Mass - a measure of the amount of matter in
an object. It can be determined by weighing
an object with a balance.
• Evaporation - the process of a liquid drying
up. The liquid turns to a gas and goes into
the air.
• Crystal - the solid form of a material that can
be identified by its properties, such as shape,
color, and pattern

15. Content
• How can you separate a solution?
• When a solution evaporates, it leaves the
dissolved solid material behind.
• How can you identify the material left behind
by evaporation?
• If the evaporation material forms a crystal, it
can be identified by its properties, such as
shape and pattern.
• Your questions?