S

SolutionsSolutes, Solvents & Solutions

Mixtures

You should be able to recall what a mixture is. Two or more substances that are mixed together but not

chemically bonded to each other. Easiest example is saltwater or seawater

The proportion in a mixture is not fixed If you have lots of salt or very little salt the mixture is still

considered saltwater

Solutions

Solutions are mixtures in which soluble particles are completely dissolved in a liquid or a gas. Made up of a;

Solute Solvent

We will use coffee as an example of a solution The substance that dissolves is called the solute

In this example the coffee granules The substance that does the dissolving is called the solvent

In this example the hot water

Solutions

Black Tea

Mi-Wadi

Seawater

Wine

Fizzy Drinks

Substance Solvent Solute

Water

Water

Water

Water

Water

Tea

Flavours and Sugar

Salt

Flavours/Sugar/Carbon Dioxide

Grape Juice and AlcoholWater is called the universal solvent, as it can dissolve many substances

Solvents

Water is described as the universal solvent However there are other solvents

Ethanol Acetone (Nail polish remover) Toluene (Paint thinner) Chloroform

Solvents can be dangerous Think of the common hazard symbols Toxic Flammable Irritant Can cause significant health issues if abused

Solutions

Solutions do not have to be made from a solid and a liquid.

Solutions can also be made by dissolving a gas into a solvent. Oxygen is dissolved in water allowing marine life to

breathe Solutions can also be made from a liquid mixing with

another liquid Alcohol is dissolved in wine, beer, etc.

Dilute vs Concentrated

We can change the strength of the solution, i.e. its taste, colour, smell , etc… by changing the amount of solute used.

A dilute solution has a small amount of solute in a large volume of solvent.

A concentrated solution has a large amount of solute in a small volume of solvent

Soluble vs Insoluble

If a substance is soluble it will dissolve in a liquid and if it is insoluble it will not dissolve Calcium carbonate is not soluble in water because the

calcium carbonate and water particles are not able to mix. Copper sulfate is soluble in water because the copper sulfate

and water particles are able to interact and mix together.

Calcium Carbonate Copper Sulphate

water

Immiscible Liquids

Liquids that do not mix together are called immiscible liquids

Examples are Oil and water Toluene and water Gasoline and water

Liquids that do mix together are called miscible

oilwater

Suspensions

Suspensions are mixtures in which insoluble particles are suspended in a liquid or gas.

Examples of suspensions are; Milk Oil shaken in water Dust in air Sandy water

Insoluble substance

+ Solvent = Suspension

Sand + Water = Sandy water suspension

Conservation of Mass

If 10g of salt is added to 50g of pure water than the solution should have a mass of 60g.

+ =

50 g 10 g+ = 60 g

Solutions

The amount of solute that can dissolve in a solvent at a given temperature is called its solubility

The amount of a solute that can dissolve in a solvent can be increased by increasing a solvent’s temperature This is generally true A gas’ solubility decreases as the solvent temperature increases

Problem with the oceans warming due to climate change.

A solute will not dissolve in a solvent indefinitely. Eventually it reaches a limit where no more will dissolve

At this point the solution is described as saturated

Solubility Curve

Supersaturated solutions are very saturated indeed.

The solute will stay in solution until a ‘seed’ crystal is added, and then it will crystallise out of the solution very quickly.When it does this, it gives out heat energy. Supersaturated solutions are therefore used in heat packs.