Concentration and Solubility - Grade 7 Science is Awesome!
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Transcript Concentration and Solubility - Grade 7 Science is Awesome!
Concentration and
Solubility
Grade 7 Science: Pure Substances and Mixtures
Learning Goals / Success Criteria
I can describe the concentration of a solution in
qualitative and quantitative terms.
I can describe the difference between saturated and
unsaturated solutions.
Key terms: concentrated solution, dilute solution,
concentration, saturated solution, unsaturated solution
Concentration and Solubility
Did you know apple seeds contain tiny amounts of a
toxic chemical called cyanide? Eating a few of these
will not harm us, but eating a large amount will have an
effect on the human body.
Pure substances can be good or bad for you depending
on how much of the substance you consume (think of
aspirin!).
Doctors need to know how much of a substance there is
in a solution when prescribing medication.
Concentration and Solubility
The words “concentrated” and “dilute” are used to describe how much
solute is in a certain volume of solution.
Concentrated solution: a solution with a large number of
solute particles in a given volume of solution
Dilute solution: a solution with a small number of solute
particles in a given volume of solution
Concentration and Solubility
Calculating Concentration
Concentration: the amount of solute present in an
amount of solution
The more solute dissolved, the greater the
concentration.
This concentration can be expressed in mathematical
terms:
Suppose 100ml of solution contains 5.0g of sugar. The
concentration of sugar in that solution is 5.0g/100ml (a
ratio!).
Calculating Concentration
The following is the equation for calculating
concentration:
Concentration = mass of solute in grams
100 ml of solution
Practice: Suppose a solution contains 6.0g of sugar in
200ml of solution. What is the concentration of the sugar
and water?
Saturated and Unsaturated Solutions
What would happen if you were mixing Kool-Aid and
you kept adding drink powder?
Eventually, no more powder would dissolve and the
solution would be saturated.
Saturated solution: a solution in which no more solute
can dissolve
Unsaturated solution: a solution in which more solute
can be dissolved
Solubility
We now know there is a limit to the amount of solute that
can dissolve in a solvent. Chemists call this amount
solubility.
Solubility: a measure of how much solute can dissolve in
a solvent to form a saturated solution at a particular
temperature and volume.
Different solutes have different solubilities (e.g. sugar
dissolves more easily than salt) and different factors
affect solubility (something you will be exploring!)