Solutions and Their Characteristics

In 2010, Hamilton, Ontario, issued warnings about potential lead contamination in drinking water, especially in homes built before 1955.
Lead pipes connecting homes to the main water supply were the primary cause.
Chronic lead exposure is dangerous because it impairs brain and nervous system development, particularly in children.
Lead reacts with water (especially acidic water), releasing toxic lead ions into the water.
The longer water is in contact with lead pipes, the higher the concentration of lead ions.
Officials advised residents to run taps for five minutes before using water, but replacing lead pipes is the better solution.

Tap water contains dissolved substances, including naturally occurring minerals and gases, as well as intentionally added substances like chlorine (for disinfection) and fluoride (to prevent dental decay).
Municipalities conduct tests to ensure tap water is safe to drink.

A solution is a homogeneous mixture of two or more substances, meaning it has only one phase and uniform mixing.
Samples from different locations in a solution have the same composition.
Solutions can be solids, liquids, or gases.
Liquid and gaseous solutions are transparent because their components are too small to block light.
Solutions may be colored or colorless depending on the substances they contain.

Glucose (C6H12O6) is dissolved in water to create an intravenous (IV) drip solution.
After mixing, glucose grains are no longer visible; molecules separate and disperse evenly.
Each glucose molecule is in direct contact with water molecules and won't settle due to their small mass.
The diameter of these molecules is approximately 10^{-9} m, allowing light to pass through, resulting in a clear, homogeneous mixture.

Solutions are homogeneous mixtures with uniform composition and only one phase.
Heterogeneous mixtures have two or more phases (e.g., oil and vinegar).
Blood and milk appear homogeneous but are heterogeneous upon closer inspection (microscopically).
Translucent or opaque liquid and gaseous mixtures are heterogeneous.

Dry, clean air is a homogeneous mixture (solution) of nitrogen, oxygen, argon, and carbon dioxide.
Classroom air can appear homogeneous, but dust particles deflect light, proving it's a heterogeneous mixture.

A solution consists of a solute (lesser quantity) dissolved in a solvent (greater quantity).
In a glucose solution, glucose is the solute, and water is the solvent.
White rum is a 40% by volume solution of ethanol (solute) in water (solvent).
Solutions can contain multiple solutes.

Concentration describes the ratio of solute quantity to solution or solvent quantity.
\text{Concentration} = \frac{\text{Quantity of Solute}}{\text{Quantity of Solution or Solvent}}
A concentrated solution has a high quantity of solute, while a dilute solution has a low quantity of solute.

Urine composition varies and consists of water and dissolved solutes excreted by the kidneys.
Changes in urine composition can indicate medical conditions.
Dilute urine (from drinking plenty of water) is pale yellow, while concentrated urine (from dehydration) is darker.
Excess water-soluble vitamins are excreted in urine.

Solutions exist in different states: gaseous (air), aqueous (urine), and liquid (gasoline).
Gasoline is a solution of liquid hydrocarbons and other solutes.
Different gasoline grades have varying solute compositions.

An alloy is a solution of two or more metals (e.g., gold jewelry alloyed with silver and copper).
Gold purity is measured in karats (24k is pure gold; 14k is 58% gold).

An amalgam is an alloy of mercury with other metals (e.g., silver-colored dental fillings).
Mercury can form an amalgam with gold, discoloring it.

Solutes and solvents can be solid, liquid, or gas, resulting in various solution types.
Metals form alloys when heated until molten.

Adding acid to thiosulfate ions in water decomposes them, producing sulfur atoms that clump together to form visible particles.
This reaction distinguishes solutions from other mixtures that appear homogeneous.
Sodium thiosulfate, hydrochloric acid, distilled water are mixed and observed for changes.

Homogeneous mixtures have one visible phase; heterogeneous mixtures have more than one.
Solutions are homogeneous mixtures of solutes in a solvent and can be solids, liquids, or gases.
The solvent is present in the greatest quantity.
Concentration measures solute quantity per unit volume of solution.
Concentrated solutions have a high solute quantity; dilute solutions have a low solute quantity.
Solutions of metals are called alloys.