Solutions and

Concentration

What is a solution?

Homogeneous mixture of solute and solvent

Solute: substance dissolved

Often a solid

Solvent: substance in which the solute is dissolved

Usually a liquid

Recall Secondary 1-3

Homogeneous mixture

A mixture where you cannot see the difference

between the different substances involved in the

mixture

More definitions

Aqueous solution

Aqua = water

A solution where water is the solvent

I take a spoonful of Nesquik powder and mix it into my

milk to make chocolate milk.

What is the solute?

What is the solvent?

What is the solution?

Example of a solution

Nesquik powder

Milk

Chocolate Milk

What does it mean when something is more concentrated

than something else?

Example

More/less concentrated

What is concentration?

The amount of substance within a given volume

𝐂 =𝑴

𝑽C: concentration

m: mass of solute

V: volume of solution

More/less concentrated?

4L

1L

m=8g

V=4L

m=2g

V=1L

C=𝑚

𝑉

𝐶 =8𝑔

4𝐿C=2g/L

𝐶 =2𝑔

1𝐿C=2g/L

Consider 3 containers of water,

3 L

2 L

1 L

Consider 3 containers of water, each with cubes of sugar

dissolved into them.

Each cube represents an equal amount of sugar dissolved in the

water.

.

.

1 L

3 L

2 L

1 L

3 L

The water from which container would taste the sweetest?

The water from which container would taste the least sweet?

2 L

1 L

2 L

3 L

1 L5

= 5L 2 L

7= 3.5 L 3 L

12= 4 L

Highest

Concentration

of Sugar

Lowest

Concentration

of Sugar

Practice Problem –

Calculating ConcentrationIan is feeling a little under the weather and decides to make himself some tea. To make it a little more appealing he decides to add 15g of sugar to his teapot which contains 1.5L of tea. What is the concentration of his sweetened tea in g/L?

V=1.5L

m=15𝑔 C =𝑚

𝑉

C =15𝑔

1.5𝐿C = 10g/L

Converting Units

kg g mg

x1000 x1000

÷1000 ÷1000

Converting Units

kL L mL

x1000 x1000

÷1000 ÷1000

Practice Problem –

Calculating Concentration2. Jenna made herself 50ml of Kool-Aid by dissolving 2.5g of the

powder into water. What is the concentration of the Kool-Aid in

g/L?V=50ml

V=0.050𝐿

Remember, we need liters!

V=50𝑚𝑙 𝑥1𝐿

1000𝑚𝑙

m=2.5𝑔

C =𝑚

𝑉

C =2.5𝑔

0.050𝐿C = 50g/L

Rearranging the Equations

Example

Emma wants to make 125ml of a 8g/L saline solution. How

much salt will she need to use?

C= 8g/L

m= ?

V = 125ml

= 0.125L

C =𝑚

𝑉8𝑔

1𝐿=

𝑥 𝑔

0.125 𝐿

𝑥 = 1 𝑔

Example

What is the maximum volume that Cory can make of an

80g/L solution of chocolate milk if he only has 23g of Nesquik

powder?

C= 80g/L

m= 23g

V = ? ml

C =𝑚

𝑉80𝑔

1𝐿=23𝑔

𝑥 𝐿

𝑥 = 0.2875𝐿 = 287.5𝑚𝐿

Concentrations in Percent

What is percentage?

“per 100”

Percentage 10

10

What percentage of the squares are grey?

Grey squares

= 20

Total squares

= 100

Percentage

= 20%

We can also measure concentration in % (m/V)

Percent (m/V)

What is the % concentration?

1 ml of water (solvent)

1 g of solute

C=?

m= 2g

V = 25ml

C= 𝑚

𝑉=

2𝑔

25𝑚𝑙

2𝑔

25𝑚𝑙=

𝑥𝑔

100𝑚𝑙

8%

2𝑔

25𝑚𝑙=

8𝑔

100𝑚𝑙

Situation Which drink has the highest

concentration of sugar?

Practice Problem

1. What is the % concentration of sugar in

a 355ml can of Coca-Cola?

C=?

m= 42g

V = 355ml

C= 𝑚

𝑉=

42𝑔

355𝑚𝑙

42𝑔

355𝑚𝑙=

𝑥𝑔

100𝑚𝑙

11.83%

Practice Problem

2. What is the % concentration of sugar in

a 591ml bottle of Gatorade?

C=?

m= 35g

V = 591ml

C= 𝑚

𝑉=

35𝑔

591𝑚𝑙

35𝑔

591𝑚𝑙=

𝑥𝑔

100𝑚𝑙

5.92%

Practice

3. What is the maximum volume that Will can make of an 8%

solution of chocolate milk if he uses 24g of Nesquik powder?

C= 8%

m= 24g

V = ? V=300ml

C= 𝑚

𝑉

8%= 24𝑔

𝑉8𝑔

100𝑚𝑙=

24𝑔

𝑉