AP Chemistry Unit 4 Exam

What are other oxidation number rules?

- H is usually +1 when bonded to a nm and -1 when bonded to a metal - fluorine always has an oxidation # of -1 - the sum of all oxidation numbers in a neutral compound is zero - the sum of all oxidation numbers in a polyatomic ion equals the charge

What are gas evolution reactions?

- carbonate (CO32-) + acid -> salt + H2O - sulfite (SO32-) + acid -> salt + H2O

Oxidation-Reduction (REDOX) reactions

- redox reactions involve transfer of one or more electrons between reactants - the rusting of iron is an example

What are the four driving forces?

1. transfer of e- (redox) 2. formation of water (H2O); neutralization 3. formation of a solid 4. formation of a gas

Physical and chemical changes?

A physical process involves changes in intermolecular attractions. Bonds are generally not broken and/or formed when a substance undergoes a physical change

What are Bronsted-Lowry acids and bases?

Bronsted-Lowry acids-base reactions involve a transfer of one or more protons (H+) from the acid to the base - a bronsted-lowry acid is a proton (H+) donor, and a bronsted-lowry base is a proton (H+) acceptor - the products of a bronsted-lowry acid- base reaction are often water and ionic compound (salt)

What is a chemical change

Chemical changes occur when a substance undergoes a reaction and a new substance is formed (heat, light, flammability, new substance, precipitate)

Based on the Brønsted-Lowry theory of acids and bases, which of the following species can act as both a conjugate acid and a conjugate base?

Correct.HS− can accept a proton to form H2S, its conjugate acid. Also, HS− can donate a proton to form S2−, its conjugate base.

What is decomposition?

DESTROYING A COMPOUND via ENERGY electricity + ionic compound -> elements

What is a single replacement?

Element + compound alkali earth metal + water -> metal hydroxide + hydrogen gas ex. 2Li(s) + 2H2O (l) -> 2LiOH(aq) + H2 (g)

What are the strong acids? (strong electrolyte)

HCl, HBr, HI, HNO3, HClO3, HClO4, and H2SO4

What are weak acids (weak electrolyte)

HF, HC2H3O2 (acetic acid), H2CO3 (carbonic acid), H3PO4 (phosphoric acid), and many more

What are conjugate acid-base pairs?

In an acid-base (protein transfer) reaction every acid has a conjugate base formed by removing an H+ and each base has a conjugate acid.

What are synthesis / combination reactions?

MAKING A COMPOUND metal + oxygen -> most common oxide ex 4Li(s) + O2(g) -> 2Li2O(s) alkali metal oxide or alkaline earth metal oxide + water -> metal hydroxide ex. Li2O(s) + H2O(l) -> LiOH(aq)

What are weak bases (weak electrolyte)

NH3 (ammonia), C5H5N (pyridine), and several more, all containing "N"

What are the salts? (strong electrolyte)

NaCl, KBr, MgCl2, and many, many more

What are the strong bases? (strong electrolyte)

NaOH, KOH, LiOH, Ba(OH)2, and Ca(OH)2

What are formation of a solid or precipitation reactions?

Precipitation reactions; these solubility rules only apply if the substance s are in water. if they are not in water, then they would be solid RULES (IN ORDER) 1. Salts formed with group 1 cations and NH+4NH4+ cations are soluble. There are some exceptions for certain Li+Li+ salts. 2. Acetates (C2H3O−2C2H3O2−), nitrates (NO−3NO3−), and perchlorates (ClO−4ClO4−) are soluble. 3. Bromides, chlorides, and iodides are soluble. 4. Sulfates (SO2−4SO42−) are soluble with the exception of sulfates formed with Ca2+Ca2+, Sr2+Sr2+, and Ba2+Ba2+. 5. Salts containing silver, lead, and mercury (I) are insoluble. 6. Carbonates (CO2−3CO32−), phosphates (PO3−4PO43−), sulfides, oxides, and hydroxides (OH−OH−) are insoluble. Sulfides formed with group 2 cations and hydroxides formed with calcium, strontium, and barium are exceptions.

What do the formation of bubbles tell us about a reaction?

That reaction underwent a chemical change because the formation of gas is possible evidence that a reaction has occurred.

A student was given two clear liquids; a colorless liquid and a dark-blue liquid. The student was asked to combine the liquids in a beaker and record observations. Which of the following results, if true, would provide the best evidence that a chemical change took place when the liquids were combined?

The resulting mixture was cloudy because the formation of a solid (precipitate) can result in the development of cloudiness, and the solid may eventually be visible at the bottom of the beaker. The formation of a precipitate is possible evidence that a chemical change has occurred.

What is a physcial change?

When a substance undergoes a physical process, the composition does not change (ex. shape, solubility at different temperatures, and phase changes)

What are combustion reactions?

a hydrocarbon and O2 undergoing an exothermic reaction (giving off heat) to produce CO2 + H2O

What are formation of water or neutralization / acid and base reactions?

an arrhenius acid and base will produce salt and water

What are elements with an oxidation number of zero?

h2, fe, o2, ca, ag, n2, al

Monatomic ions have oxidation numbers equal to their charge

li+, s2-, h+, o2-, mg2+

What are oxygen's oxidation numbers

oxygen in a compound most often has an oxidation # of -2, one notable exception is peroxides, like h2o2, where oxygen has an oxidation # of -1

What is the equivalence point?

the point at which neutralization occurs (# moles in acid = #moles in base)

What are acid-base reactions?

when a solution of an acid and a base are mixed, a neutralization reaction occurs - BL acid is a proton donor, and BL Base is a proton acceptor