Solutions and mixtures

Look at the pictures in the next few slides, can you tell what these substances are made of?

Can you divide them into categories?

The two categories... Homogeneous mixtures Heterogeneous mixtures

Mixtures Homogeneous It is composed of two or more substances You can see only one phase. It can only be a gas, liquid or solid. Heterogeneous It is composed of two or more substances. You can see many phases It may be a combination of solids, liquids, or gases Ex: air! Is a gaseous mixture. A spoon! Is made of steel, which is a mixture of iron, carbon, and nickel A salty solution: is made of salt and water, but you only see the liquid phase. Ex: Soft drink: bubbles of gas in a liquid phase A piece of marble! Is a mixture of solid phases. Raisin bread: is made of doe and raisins, two solid phases. Also gas in the doe.

Are the following substances homogeneous or heterogeneous? Liquid Gas Heterogeneous Soft Drink

A cup of coffee Homogeneous

Granite Two solid phases: heterogeneous

-The particles of different substances are uniformly distributed -The properties of mixture are identical throughout the mixture. -The particles of different substances are NOT uniformly distributed -The properties of mixture are NOT identical throughout the mixture.

SOLUTIONS A solution is a homogeneous mixture in which one or more substances are dissolved into another substance. Ex: Salt and water, or a cup of coffee, cleaning products, various creams, etc.

The dissolved substance is called the solute. It can be solid (ex: salt), liquid (ex: alcohol), gas (carbon dioxide)= it is always the smallest quantity The solute is dissolved into another substance called solvent. Ex: water= it is always the larger quantity SOLUTESOLVENTSOLUTION Ex: Sugar (solute) + Water (solvent) = sugar solution This mixture will have new physical properties, but the nature of the substances will not change. (Sugar is still sugar, but in a diluted form, and water is still water, but now it’s sweet, they physically changed, not chemically)

We then say sugar is soluble in water, it has dissolved. If we put too much solute and we start to see it at the bottom of the container, then the solution is saturated.

Suspensions Sometimes when we mix substances they stay in clusters. We therefore say it is insoluble in water. E.g. Chalk + Water = Suspension Eventually the particles sink to the bottom to form sediment.

Mixtures In Liquids When two liquids totally mix they are said to be miscible. An example of this would be alcohol and water. When to liquids do not mix they are said to be immiscible. An example would be oil and water: EMULSION OCCURS