Unit A: Mix and Flow of Matter
Section 2.2 & 2.3 Concentration and Solubility
A solution is made up of two parts:
Solute: The substance that is being dissolved (ex. Salt)
Solvent: The substance that is doing the dissolving (ex. Water)
Soluble means to be able to be dissolved in a particular solvent. Solutes and solvents can be
gases or liquids.
Water is known as the Universal Solvent
When you dissolve anything into something else you get a SOLUTION.
We can measure the amount of SOLUTE in any SOLVENT by calculating the CONCENTRATION of
the solution.
Measuring Concentration
The concentration of a solution is the actual amount of solute in a specific amount of solvent.
Concentration =
𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒
𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡
For example: 50 grams of solute dissolved in 100 ml of water. What is the concentration?
Concentration =
50𝑔
100𝑚𝑙
Comparing Concentrations
To compare concentrations of two solutions, you need to know the amount of solute in the
same volume of solvent for each solution.
Solution 1
10g of salt in 50ml of water
Solution 2
More
concentrated
25g of salt in 100ml of water
10𝑔
50𝑚𝑙
=
20𝑔
100𝑚𝑙
25𝑔
100𝑚𝑙
Which has a higher concentration? Place a star beside your prediction and then calculate to find
the correct answer.
Solution 1
More concetrated
12g of salt in 50ml of water
Solution 2
17g of salt in 100ml of water
12𝑔
50𝑚𝑙
2
24𝑔
2
100𝑚𝑙
x =
12𝑔
50𝑚𝑙
=
24𝑔
100𝑚𝑙
17𝑔
100𝑚𝑙
Saturated and Unsaturated Solutions

A Saturated solution is one in which no more solute will dissolve in a specific amount of
solvent at a specific temperature.

An Unsaturated solution is one in which more solute can be dissolved in a specific
solvent at the same specific temperature
Supersaturated solutions - a solution that contains more solute than would normally dissolve
at a certain temperature is called a super-saturated solution.
When no more solute can be added to a solution, we say that we have reached the Saturation
point. This is the point of no return. Absolutely no more solute can be added. Unless you
change something in the solution. This is all related to the solubility (the maximum amount of
solute that can be dissolved in a fixed volume of solvent at a given temperature.)
Section 2.3 Factors affecting solubility
Factors Affecting Solubility
How well a solute dissolves in a solvent depends on three main factors:
1. The type of solute
2. The type of solvent
3. The temperature of the solution
Solubility Changes with Temperature
Solubility increases as the temperature of the solvent increases, because more space is
provided between the particles for the solute particles to fit (dissolve) into. The reverse is true
for a gas though - as the temperature increases, the solubility of a gas, in a liquid solvent
decreases.
Thermal Pollution
If the temperature of water increases (warm industrial waste water poured directly into lakes
and rivers) then there is less oxygen that can be dissolved in the water because the oxygen
“bubbles out” of the water– thus, affecting the living organisms in the water. This is called
thermal pollution.
Section 2.2 – Concentration and Solubility Questions
1. What does the term CONCENTRATION refer to when talking about fluids?
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2. If a solution has a concentration of 75 g per 100 mL, what does this mean?
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3. Calculate the concentrations in grams per 100 mL for the following solutions:
a. 10 g of chocolate in 50 mL of water.
b. 3 g of sugar in 300 mL of water.
c. 2.5 g of maple syrup in 25 mL of water.
4. Which one of the above solutions has the highest concentration? Which has the
lowest?
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5. What is the difference between a saturated solution and an unsaturated solution?
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6. Identify the solutes and the solvents in the following solutions:
a. Kool-Aid ______________________________________________________
b. Coffee ____________________________________________________
c. Air ______________________________________________________
d. Seawater ______________________________________________________
e. Pepsi ______________________________________________________
Section 2.3 – Factors Affecting Solubility Questions
1. Why water is called the “universal solvent”?
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2. What three factors affect the solubility of a solute? Explain each one briefly.
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