Solutions
Solution: A solution is a well-mixed mixture that contains a solvent and at least one solute.
Solvent: A solvent is the part of a solution present in the largest amount, it dissolves the other substances.
Solute: A solute is the substance that is present in a solution in a smaller amount and is dissolved by the solvent.
A solution has the same properties throughout. It contains solute particles that are too small to see.
Water is the most common solvent; it is often called the "universal solvent"
Examples: salt in water, sugar in water, tea, gasoline
Colloids and Suspensions
A colloid is a mixture containing small, undissolved particles that do not settle out.
The particles are too small to be seen easily, but large enough to scatter a light beam.(this is called the
Tyndall Effect)
Ex: milk, gelatin, fog, whipped cream
Not all mixtures are solutions, some are colloids and suspensions.
A suspension is a mixture in which particles can be seen and easily separated by settling or filtration. the particles are large enough to see.
Ex: pepper and water, a snow globe
Particles in a Solution
When a solution forms, particles of the solute leave each other and become surrounded by particles of a solvent.
Effects of Solutes on Solvents
Melting is changing from a solid to a liquid. The point at which a substance melts is its melting point. the melting point of pure water is 0 degrees Celsius
(W) Melting points are often used to identify unknown substances.
Freezing is changing from a liquid to a solid; a substances freezing point is where it begins to freeze. the freezing point of pure water is also 0 degrees Celsius

(W) Solutes lower the freezing point and raise the boiling point of a solvent.
Lower freezing points - solute particles make it harder for the water molecules to form crystals. (Water must drop below 0 C to freeze)
Higher Boiling Points - Solutes make it harder for water molecules to escape as a gas, so it makes it harder for it to boil. (Water must go above 100 C to boil)
Concentration
Sap and Syrup differ in their concentrations:
(W) The sap is a dilute solution and the syrup is a concentrated solution.
(W) A dilute solution is a mixture that has only a little solute dissolved in a certain amount of solvent.
(W) A concentrated solution is one that has a lot of solute dissolved in the solvent.
(W) You can change the concentration of a solution by adding more solute or by adding or removing solvent.
Measuring Concentration
To measure concentration, you compare the amount of a solute to the amount of a solvent or to the total amount of solution.
Solubility
(W) Solubility is a measure of how much solute can dissolve in a solvent at a given temperature.
(W) A saturated solution contains as much dissolved solute as is possible at a given temperature.
(If you add more solute, it will not dissolve, it will settle at the bottom of the container)
(W) the solute that settles at the bottom is called the precipitate. (It is not part of the solution)
(W) In an unsaturated solution, you can add more solute and the solvent will still dissolve it.
Soluble - something that can be dissolved
Insoluble - something that can't be dissolved
(W) The solubility of a substance tells you how much solute you can dissolve before a solution becomes saturated.

(W) Solubility can be used to help identify a substance
Factors Affecting Solubility
- pressure
- solvents
- temperature
Pressure - Pressure affects the solubility of gas. The higher the pressure, the more gas can dissolve.
Solvents - Some solutions and solvents are not compatible (Oil and water). Why? Polar compounds do not mix well with nonpolar compounds.
Temperature - For most solids, solubility increases as the temperature increases.
(W) A super saturated solution has more dissolved solute than is predicted by its solubility at the given temperature.
Acids
(W) an acid is a substance that tastes sour, reacts with metals and carbonates, and turns blue litmus paper red.
(W) More properties of Acids:
Contains hydrogen ions (H+) when dissolved in water
Has a pH less than 7

Examples:
Hydrochloric acid (HCl)
Sulphuric acid (H2SO4)
Nitric acid (HNO3)
Carbonic acid in soft drink (H2CO3)
Ascorbic acid (Vitamin C) in fruit
Citric acid in oranges and lemons
Acetic acid in vinegar
Tannic acid (in tea, grapes and wine)
Bases
(W) a base is a substance that tastes bitter, feels slippery, and turns red litmus paper blue.
Bases are often called the "opposite" of acids.

Examples of Bases:
Blood
Antacid
Baking soda
Ammonia
Egg whites laundry detergent pH Scale
(W) The pH scale measures how acidic or basic a solution is.
(W) the pH scale is a range of values from 0 to 14. It expresses the concentration of hydrogen ions in a solution.
(W) Acids have a pH from 0-7
(W) Bases have a pH from 7-14
Lower pH value indicates a stronger acid.
Higher pH value indicates a stronger base.
What happens when the pH of a substance is 7?
(W) A pH level of 7 indicates a Neutral Substance i.e: Water!