Which are solutions?

Solutions

A. A solution is a uniform mixture of substances.

1. Types of solutions:

solid in liquid: NaCl in water Na+, Cl-, H20

gas in gas: Air (N2, O2, Ar, etc)

solid in solid: Bronze (Cu and Sn) = an alloy

gas in liquid: CO2 in H2O

liquid in liquid: alcohol in H2O

liquid in solid: Hg in Ag

2. solute: substance being dissolved

the smaller amount

solvent: dissolves the solute

the greater amount

Ex. solution solute solvent

salt water

air

NaCl water

O2 N2

3. The most common solvent: water

Water solutions are called aqueous (aq)

Ex: In water: NaCl(s) Na+(aq) + Cl-(aq)

solid water

Water H2O is polar. It has a + and – side:

H H

O

+ +

-

Attracts + charges

+ -

Attracts - charges

NaCl dissolves because:

+-

+-

Na Cl

Ex. Surface tension occurs because water molecules attract each other.

Oil is nonpolar.

H2O cannot pull it apart.

It does not dissolve in water.

Olive oil:

Diesel oil:

Pentane:

Oil slicks

Rule: Likes dissolve likes:

1. Polar substances dissolve polar ones.

Ex. NaCl in water

2.Nonpolar substances dissolve nonpolar ones.

Ex. Oil in turpentine

3. Nonpolar ones do NOT dissolve nonpolar ones.

Ex. Water does not dissolve oil.

4.

An electrolyte conducts electricity in a solution because

the solute is ions.

Ex: Na+ and Cl- are charged. They conduct.

Which solution contains electrolytes?

4.

An electrolyte conducts electricity in a solution because

the solute is ions.

Ex: Na+ and Cl- are charged. They conduct.

Non-electrolyte: solution does not conduct electricity.

Ex: Sugar (C6H12O6) is not charged.

It’s what plants crave.

http://www.youtube.com/watch?v=e1fKzw05Q5A

5. Particles in solution are too small to filter out, but they can be separated by other physical means.

Ex Desalination of sea water by distillation When salt water is boiled, the salt remains. The pure water can be condensed and used.