Grade 11 chemistry - Water and solutions

Evaporation and condensation

As water evaporates, any solutes are left behind. The evaporated water, when it condenses, is very pure

Filtration

As water passes through sand and gravel in the ground, suspended matter is filtered out

bacterial action

Soil bacteria decompose organic contaminants into simpler, less toxic substances as water percolates through the soil

water cycle

the flow of water on, above, and below the surface of earth

Transpiration

The evaporation of water from the leaves of a plant

Aquifer

A layer of underground rock that holds a considerable quantity of water; an important source of fresh water

potable

water that is suitable for drinking

significance of high melting and boiling points

-permits water to exist as a liquid at room temperature

-keeps body fluids liquid over a large range of temperatures

significance of expansion when cooling from 4 C to 0 C

-causes ice to float

-causes water to freeze from the top down, allowing life to continue below it

Significance of High surface tension

-pulls water into round droplets

-allows small insects to “walk on water”

Significance of ability to exchange thermal energy with little change in temperature

-enables water to absorb a great deal of thermal energy for a small increase in temperature and to release a great deal of energy for a small decrease in temperature

-has a moderating effect on temperature changes in organisms and the environment

Significance of inability to mix with non-polar compounds

-enables organisms to retain water because of a water proof coating

-allows organisms to store non-polar substances

heterogeneous mixture

a mixture that contains two or more phases

concentration

the ratio of the quantity of solute to the quantity of solution of solvent; usually quantity of solute per unit volume of solution

concentrated solution

a solution with a relatively large quantity of solute dissolved per unit volume of solution

dilute solution

a solution with a relatively small quantity of solute dissolved per unit volume of solution

alloy

a solution of two or more metals

amalgam

an alloy(solution) or mercury with other metals

aqueous solution

a solution in which water is the solvent

hydration

the process in which ions are surrounded by water molecules

dissociation

the separation of individual ions from an ionic compound as it dissolves in water

miscible

able to mix to form a solution; usually describing liquids that mix with each other in all proportions to form a solution

immiscible

unable to mix to form a solution; usually describing liquids that do not readily mix

surfactant

a compound that can reduce the surface tension of a solvent; surfactants have both a hydrophobic part and a hydrophilic part

saturated solution

a solution in which more solute can dissolve at a given temperature and pressure

unsaturated solution

a solution in which more solute can dissolve at a given temperature and pressure

supersaturated solution

A solution that contains more than the maximum quantity of solute that it should at a given temperature and pressure

solubility curve

a graph of the solubility of a substance over a range of temperatures

thermal pollution

an increase in water temperature, usually as a result of warm water being added to an aquatic ecosystem

pressure (P)

force per unit area; unit is the pascal, unit symbol Pa; 1 Pa = 1N/m²

amount concentration

the amount (in moles) of solute dissolved per litre of solution; unit symbol mol/L

stock solution

a concentrated solution that is used to prepare dilute solutions for actual use

standard solution

solution for which the precise concentration is known

dilution

the process of reducing the concentration of a solution; usually done by adding more solvent