Grade 11 Pre-AP Chemistry - Unit 4 Test Review

Arrhenius Theory

Acids:

-sour taste

-contain H+ ions

-pH > 7

-releases H2 gas with metals

-releases CO2 gas with carbonates

Bases:

-bitter taste

-contain OH- ions

-pH < 7

-feels slippery

-reacts with CO2 to form carbonate precipitate

Both:

-corrosive

-electrolyte

Problems with Arrhenius' Theory

1. Some bases do not contain OH-

2. According to Arrhenius' Theory, a substance can only act as either an acid or base, not both. Some substances can act as both.

Bronsted-Lowry Theory

Acids: proton (H+) donors

Bases: proton (H+) receivers

Litmus Paper indicator colours

acid: red

neutral: purple

base: blue

Phenolphthalein indicator colours

acid: colourless

neutral: colourless

base: pink

Bromothymol Blue indicator colours

acid: yellow

neutral: green

base: blue

Methyl Red indicator colours

acid: red

neutral: orange

base: yellow

nitrate and phosphate contaminants

come from fertilizers

heavy metal contaminants (Pb, Hg, Cr, Cd)

come from mines/landfills

pesticide contaminants

come from pesticides

salt contaminants

come from roads

medication contaminants

come from household sewage

organic solvent contaminants

come from cleaners

sulfur compound contaminants

come from bacteria

Concentration of HCl

12.0M

Concentration of H2SO4

18.0M

Dissociation vs. Ionization

dissociation starts with an ionic compound

ionization starts with a molecular compound

List 3 ways to increase the rate of dissolving and explain

1. Heat it up

-allows the particles to have more E and move faster, resulting in more collisions, resulting in more bonds being broken so the particles can separate + dissolve

2. Swirl the solution

-same reasons as 1

3. Add more solvent

-increases the number of particles available for collisions, resulting in more collisions + more bonds being broken

amphiprotic/amphoteric

a substance that can act as either an acid or a base

polyprotic acid

an acid that can donate more than one proton

Process of Titration

1. burette is filled to the top (where the 0 mark is) with a solution with a known concentration (titrant)

2. analyte (solution with unknown concentration) goes in the erlenmeyer flask with a few drops of indicator

3. add titrant while constantly swirling

4. stop when the solution has achieved the lightest possible permanent colour change throughout (endpoint)

Process of Dilution

1. Calculate the amount of stock solution needed to achieve the desired concentration (V1)

2. Add that volume of stock solution to an erlenmeyer flask

3. Add water until you reach the desired volume

Ways to remove contaminants from water

-filter them out

-use chlorine to kill micro-organisms and medicine

-precipitate the contaminants by adding ions