Chemistry Quiz 2 Partial 3

Question 1

Why is the ozone layer important?

Answer 1

It’s important because it protects us from UV rays because it has enough lenght to absorb them. If we wouldn’t have it our skin would polymerize and have mistakes in our DNA

Question 2

What is a CFC?

Answer 2

Chlorine Fluoride Carbons, mostly used in spray and refrigeration, can lead to the destruction of the ozone layer.

Question 3

What type of mixtures are there?

Answer 3

Solutions, colloids and suspensions

Question 4

Properties/Description of solutions and examples

Answer 4

It’s a stable homogeneous mixture of two or more substances uniformly distributed throughout in a single phase. Ex: Sugar and water, niquel and copper (alloy).

Question 5

Properties/Description of colloids and examples

Answer 5

Known as colloidal dispersions or colloids they have medium sized particles (between 1nm and 1000nm). Colloidal particles make the dispersing space and the solvent the displacing medium, colloids are stable and heterogeneous. Ex. Milk, cheese, gelatin, smoke, fog…

Question 6

Properties/Description of suspensions and examples

Answer 6

The partciles in these dispersions are so large that they settle down unless the mixture is constantly stirred, they can be separated by a filter from the heterogeneous mixture and have a size of more than 1000 nm. Ex: Muddy water, yogurt.

Question 7

Types of solutions

Answer 7

Solute-solvent:
gas-gas
gas-liquid
liquid-liquid
liquid-solid
solid-liquid
solid-solid

Question 8

Types of colloids

Answer 8

sol(paints,mud):solid in liquid
gel(gelatin): "
liquid emulion(milk, mayonnaise): liquid in liquid
foam(whipped cream): gas in liquid
solid aerosol(smoke): solid in gas
liquid aerosols(mist): liquid in gas
solid emulsion(cheese):liquid in solid

Question 9

Concentration (% mass) formula

Answer 9

(gr. solute/gr. solution)x100 %

Question 10

Molarity formula

Answer 10

moles of solute/L solution M

Question 11

Normality formula

Answer 11

Number of chemical equivalents/L of solution or molarity times eq

Question 12

Molality formula

Answer 12

moles of solute/kg solvent, it is useful for changes in solutions (reactions)

Question 13

ppm formula

Answer 13

mg solute/kg solution, useful for small concentrations (air)

Question 14

Definition of solubility

Answer 14

Amount of grams of solute necessary to reach the saturation point or when they are in equilibrium(same thing)

Question 15

Description of the process of solubility

Answer 15

First the bonds of the solute break (dissolution process), then the bonds of the solvent break and both are endothermic processes. The previous interactions of the solvent are replaced with solvation(can be exothermic or endothermic) and cristallization(exothermic).

Question 16

Why does a solute disolve even if you don’t move it?

Answer 16

Because things like to be in disorder (thermodynamics law)

Question 17

What is solvation?

Answer 17

Ex: chlorine ions- surrounded by the positive side of water or sodium ions+ surrounded by the negative side of water.

Question 18

Types of solubility

Answer 18

Saturated (when solute can be dissolved no more
Unsaturated (solute can still be dissolved)
Supersaturated (it is unstable, you heat, dissolve, and cool).

Question 19

Factors that affect solubility

Answer 19

• The different compositions(elements)
• Temperature
• Solubility rule(polarity, polar dissolves polar(ionic also) and non-polar dissolves non-polar)
• Amount solute

Question 20

Extra things about solubility

Answer 20

You can’t dissolve infinite amounts of solute because there will be a time when the cristallization rate reaches the dissolution one, “nothing” will happen. If you dissolve something at high temperatures and cool it, even though it’s supersaturated the solution will remain the same.