Section 1

Question 1

Define a solution.

Answer 1

It is a homogeneous mixture of 2 or more substances in a single phase. It is transparent and non-filterable.

Question 2

Define solvent.

Answer 2

The substance that is in the largest amount in the solution.

Question 3

Define solute.

Answer 3

Any substance(s) present in smaller amounts in a solution. A solution may contain more than one.

Question 4

Define suspensions.

Answer 4

These are mixed, but not dissolved in each other Will settle over time Particles are bigger than 1 μm Examples: dust in air, muddy water

Question 5

Define colloid.

Answer 5

A colloid is a suspension of molecules or aggregates of molecules or ions ranging in size from 1 to 1000 nm in some medium.

Question 6

Define the tyndall effect.

Answer 6

It is scattering of light by particles.

Question 7

Define coagulation.

Answer 7

Destruction of a colloid. Usually accomplished either by heating or by adding an electrolyte.

Question 8

Define emulsion.

Answer 8

A colloidal dispersion of a liquid in a liquid Must have an “emulsifying agent” Ex) detergent, soap, egg yolk, solvents

Question 9

What are the 3 types of solubility of solutes?

Answer 9

Dissolution Process Temperature Pressure

Question 10

Define dissolution process.

Answer 10

Water dissolves ionic compounds and polar covalent molecules best. The rule is: “like dissolves like” Polar dissolves polar. Nonpolar dissolves nonpolar. Oil is nonpolar but water is polar. Oil and water don’t mix. Salt is ionic (polar) - makes salt water.

Question 11

Define molecular polarity.

Answer 11

Determined by the arrangement of the molecule. Symmetrical molecules are nonpolar. Nonsymmetrical molecules are polar.

Question 12

Define nonpolar.

Answer 12

Need to be exactly the same.

Question 13

What is the exception to the polarity rule?

Answer 13

Carbon and hydrogen bonds

Question 14

Define inter molecular forces.

Answer 14

Attractive forces between molecules. Much weaker than chemical bonds within molecules.

Question 15

Define the 3 types of IMF.

Answer 15

London dispersion Attraction between two instantaneous dipoles. Asymmetrical electron distribution for all atoms and molecules Weakest of the IMF Dipole-Dipole Forces Attraction between two permanent dipoles Force for all polar molecules Hydrogen Bonding Attraction between molecules with N-H, O-H, or F-H bonds Extremely polar bonds. Strongest IMF

Question 16

How does water interact with non-polar molecules?

Answer 16

Water doesn’t dissolve nonpolar molecules because water can not hydrogen bond to non-polar molecule. Instead, water hydrogen bonds to itself.

Question 17

How does water interact with solids?

Answer 17

Solids will dissolve if the attractive force of the water molecules is stronger than the attractive force of the crystal.

Question 18

How do ionic solids dissolve?

Answer 18

Water breaks the + and - charged pieces apart and surrounds them. Opposites attract. Salt Cation to Hydrogen in water. Salt Anion to Oxygen in water.

Question 19

What are the steps in the Interactions in the Solution Process?

Answer 19

Step 1: Expanding the Solute (solute-solute interaction) must overcome IMF or ion-ion attractions in solute requires energy, ENDOTHERMIC ( + ΔH) Called ΔH1 Step 2: Separation of Solvent (solvent-solvent interaction) must overcome IMF of solvent particles requires energy, ENDOTHERMIC (+ ΔH) Called ΔH2 Step 3: Combine solvent with solute. (solvent-solute interaction) attractive IMF form between solute particles and solvent particles “Solvation” or “Hydration” (where water = solvent) releases energy, EXOTHERMIC (- ΔH) Called ΔH3 ΔH1 + ΔH2 + ΔH3 = ΔHsoln

Question 20

Define the Temperature Effect on Solids

Answer 20

solubility increases with increasing temperature Increase K.E. increases motion and collision between solute / solvent.

Question 21

What are the exceptions to the Temperature Effect on Solids.

Answer 21

Na₂SO₄ and Ce₂(SO₄)₃ solubility decreases with increasing temperature

Question 22

What are the 3 types of solutions?

Answer 22

Saturated contains the maximum amount of solute that will dissolve in a given solvent at a specific temperature. Unsaturated contains less solute than the solvent has the capacity to dissolve at a specific temperature. Supersaturated contains more solute than is present in a saturated solution at a specific temperature.

Question 23

How do you solve a solubility curve problem?

Answer 23

Use the formula

Sat. pt. From graph X (g H₂O / 100)

Question 24

Define the Temperature Effect on Gas

Answer 24

The solubility usually decreases with increasing temperature. Increase K.E. result in gas escaping to atmosphere.

Question 25

Define the Pressure Effect.

Answer 25

* Solids/Liquids - Very little effect * They are already close together; extra pressure will not increase solubility. * Gas - Solubility increases with Pressure. * Increase pressure squeezes gas solute into solvent.

Question 26

Define Henry's Law.

Answer 26

The solubility of a gas in a liquid is proportional to the pressure of the gas over the solution. c = kP c is the concentration (M) of the dissolved gas P is the pressure of the gas over the solution k is a constant (mol/L•atm) that depends only on temperature

Question 27

How do you make a solution with solid solute?

Answer 27

1. Calculate the mass of the substance needed, and weigh out that amount. 2. Add some solvent to the solute to dissolve it, and pour this into a volumetric flask. 3. Rinse the weighing beaker with more solvent, and pour the rinse into the flask. 4. Add water until the volume nears the neck of flask. 5. Put the stopper in the flask, and swirl the solution thoroughly. 6. Carefully add solvent to the flask until the mark. 7. Restopper the flask and invert it at least ten times to ensure complete mixing.

Question 28

How do you make a solution with liquid solute?

Answer 28

1. Remove desired liquid using a Volumetric pipet 2. Transfer desired liquid to a Volumetric flask 3. Continue with steps 4-7 from how to make solution (w/solid)

Question 29

What are the 4 concentration of solutes?

Answer 29

Molarity Molality Mass Percent Normality

Question 30

Define Molarity.

Answer 30

_moles of solute_ 1 liter solution