Water – The Universal Solvent
Vocabulary:
Solute = A substance dissolved in another substance, usually the component of a solution present in the
lesser amount
Solvent = A substance in which another substance is dissolved, forming a solution
Solution = A homogeneous mixture of two or more substances
Homogeneous = a mixtures so well mixed, you can no longer see the solute and solvent. They appear as
one.
Solubility = the ability of a substance to dissolve in a liquid
Salt = In chemistry, salts are ionic compounds that are generally made for a metal bonding with a
nonmetal.
Background:
Water is often called the universal solvent because so many substances will dissolve in it. Why do so
many substances readily dissolve in water? The ability of a substance to dissolve, its solubility, is
dependent upon the molecular arrangements of the liquid and the substance. Water is a polar molecule
with positive and negative ends. For this reason, other substances with positive and negative surface
charges are attracted to the positive (+) and negative (-) ends of water and are therefore kept “in
solution”. Salts readily dissolve in water because they contain positive and negative ions (molecules)
that are attracted to the water molecules.
Ocean water contains many types of dissolved salts. Some salts are picked up by rainwater and melting
snow, are carried to rivers, and eventually end up in the ocean. Others originate within the ocean when
substances such as seashells dissolve in the ocean water and when underwater hot springs add or
remove chemicals from water. Still others make their way to the ocean through the atmosphere. These
salts ends up altering the density of seawater, and therefore, greatly affecting ocean currents and
circulation.
Materials:
Plain piece of computer paper
Test tubes
Stoppers
Test tube holder
Various labeled index cards
Graduated cylinder
Beaker of Water (H2O)
Isopropyl Alcohol (H2O2)
Baby oil
Table Salt (NaCl)
Spoons
Masking tape
Small plastic measuring containers
Procedure:
1. CLEARLY write all your group members’ names on the index card with a marker. Prepare 4 other
cards marked with the word “Start”, “15”, “30” and “45”.
2. At your table you should find 3 labeled test tubes in a test tube holder. If they are not already
labeled, please use masking tape and a marker to add the numbers 1,2,3.
3. Use your graduated cylinder to measure approximately 20mL of water into test tube 1
4. Use your graduated cylinder to measure approximately 20mL of isopropyl alcohol into test tube
2
5. ****ESTIMATE**** Pour 20 mL of baby oil into test tube 3 based on the level test tubes 1 and 2
were filled. (We will not have time to wash cylinders before the next class, so oil can’t be placed
into these)
6. Using your balance, measure approximately 5g of Table Salt into a small plastic measuring
container. Repeat this 3 times.
7. Carefully add your Table Salt to test tubes 1-3
8. Place your plain piece of paper behind your test tubes in the holder. This helps to give you some
background and blocks some of the light from coming through when you take photos.
9. Take a picture as they look when you first add the salt. If you are taking a picture, include the
index card with the word “start” as well as the card with your group’s names
10. Wait approximately 1 minute
11. Take a picture of your test tubes as they look now. If you are taking a picture, include the index
card with the word “start” as well as the card with your group’s names
12. Shake each test tube 15 times
13. Take a picture of your test tubes as they look now. If you are taking a picture, include the index
card with the word “15” as well as the card with your group’s names
14. Shake each test tube 15 additional times (30 total)
15. Take a picture of your test tubes as they look now. If you are taking a picture, include the index
card with the word “30” as well as the card with your group’s names
16. Shake each test tube 15 additional times (45 total)
17. Take a picture of your test tubes as they look now. If you are taking a picture, include the index
card with the word “45” as well as the card with your group’s names
18. Stop shaking and rest your arm. 
19. Rinse beakers 1-2 and return them to your table. Return beaker 3 (with baby oil) to a container
in the back for washing. Do not rinse the small plastic measuring containers. Leave all other
materials at your table as you found them.
20. Now take the time to look at your pictures and sketch what you see into the data section on
your last page. The most important aspect to show is how much your solute has dissolved into
the solvent. This will be the data for your lab.
Questions:
1. Which materials do you believe acted as your solutes? List and explain.
2. Which materials do you believe acted as your solvents? List and explain.
3. At any point, do you believe you created a solution? Explain using your vocab and use evidence
from your data.
4.
Which solvent had the greatest solubility? Explain using your vocab and use evidence from
your data.
5.
Which solvent had the least solubility? Explain using your vocab and use evidence from your
data.
6.
Explain why salts readily dissolve in water. Use your vocab.
7.
Why do you think your solvent (from #5) was not very soluble? Use your vocab.
8.
Why do you think shaking increased the amount of solute dissolved in your solvent?
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9.
Do you believe the density of any of your solutions changed during this experiment? Explain
using your vocab.
DATA
START
15
30
45