Chemistry: Lesson 7 Solutions

Front 1

Describe the differences between solutions, suspensions and colloids.

Back 1

Solutions < 1nm; do not settle on standing,mostly transparent.
Colloids - 1 - 1000nm; scatter light (Tyndall effect), appear milky or turbid. Fog, smoke, jello.
Suspensions - > than 1000nm; settle on standing, choc milk, paint.

Front 2

Define the term Saturation

Back 2

When a solvent contains all the solute it can hold at a given temperature.

Front 3

Define the term Supersaturation

Back 3

When a solvent holds more solute than it can normally hold at room temperature.

Front 4

Define the term Molarity

Back 4

Molarity is the concentration of molecules in a solution.

Front 5

Define the term Solubility

Back 5

The maximum amount of solute that will dissolve in a given amount of solvent under a particular set of conditions.

Front 6

Calculate concentrations of solutions as a percentage.

Calculate amount needed for 4.4% w/v KBr in 250ml solution water.

Back 6

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Front 7

Calculate concentrations of solutions as a molarity of ppm

Back 7

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Front 8

Recognise what compounds will dissolve specific solvents and how electro-negativity is important in determining this property.

Back 8

The concept of "like dissolves like".
Fats and oils are non-polar - no negative or positive charges on their molecules. Water is polar and has charge separation (H +, O -). Therefore oils, fats won't dissolve in water. To dissolve oil you need another non-polar solvent such as petrol.
Sugar and salt are polar therefore they will dissolve in water.

Front 9

Explain the process of dissolution

Back 9

The process by which molecules interact and attract each other to form a solution.

Front 10

Demonstrate an understanding of osmotic pressure using an example.

Back 10

Osmotic pressure is the amount of pressure that must be applied to stop the flow of water. Water will flow into a hypertonic solution (one with a greater concentration of a solute) from a hypotonic solution (lower concentration of solute) as the hypertonic solution has the greater osmotic pressure. Once the concentration is equal (isotonic) the flow will stop.

Front 11

Calculate how many grams of glucose (C6H12O6) are needed to make a 1L solution of 0.1M.

Back 11

1m of glucose in 1L water gives a 1M solution.
0.1m of glucose on 1L water gives a 0.1M solution.
Formula weight of glucose C6H12O6 is 180g.
Therefore 18g glucose is needed to give a 0.1M solution.

Front 12

What is a colligative property?

Back 12

Relates to solutions. Colligative properties depend on the number of particles in a solution.

Front 13

What is freezing-point depression?

Back 13

A colligative property. The decrease in the freezing point of a liquid caused by adding a solute.

Front 14

Define Osmotic pressure

Back 14

The amount of external pressure that must be applied to the more concentrated solution to stop the passage of solvent molecules across a semi-permeable membrane.

Front 15

Define Osmosis

Back 15

The passage of solvent molecules from a less concentrated solution across a semi-permeable membrane into a more concentrated solution.