General Chemistry ACS questions and answers

General Chemistry ACS questions and
answers

Law of Conservation of Mass ✔✔mass is neither created nor destroyed

Dalton's Atomic Theory ✔✔chemical compounds are formed when atoms combine with
each other

isotope ✔✔different number of neutrons

atomic mass ✔✔mass of an atom relative to "standard mass"; weighted average of
isotopes

mole ✔✔Avogadro's number
6.022 x 10²³ particles

molar mass ✔✔mass in grams of one mole of the compound

cation
anion ✔✔positive ion
negative ion

covalent bond ✔✔atoms sharing electrons between nonmetals

1. structural formula
2. chemical formula
3. molecular formula
4. empirical formula ✔✔1. individual bonds shown by lines
2. symbols
3. gives actual number of atoms
4. gives relative number of atoms

Ionic Compounds ✔✔- cation name first, anion after
- ex: CaCl₂ = calcium chloride
- charge of one becomes the quantity of the other; exception = simplification (BeS)

transition metal ions ✔✔CuCl₂ = copper (II) chloride ; same rule for charge

polyatomic ions ✔✔sulfate = SO₄²-

,sulfite = SO₃²-
phosphate = PO₄³-
acetate = C₂H₃O₂-
carbonate = CO₃²-
chlorate = ClO₃-
nitrate = NO₃-
ammonium = NH₄+

mass percent ✔✔mass % = (mass of element in compound)/(mass of compound) x
100%

How to find Empirical Formula: ✔✔1. Base calculation on 100g of compound
2. Determine moles of each element in 100g of compound
3. Divide each value of moles by the smallest of the values
4. Multiply each number by an integer to obtain whole numbers

Aqueous Solution ✔✔water is the dissolving medium/solvent

solute ✔✔- anything dissolved in a solvent (most likely water)
- changes its phase when dissolved
ex: NaCl (s) → NaCl (aq)

Precipitation Reactions ✔✔some molecules are soluble, some insoluble; insoluble
molecules are called "precipitates"

Electrolytes ✔✔- strong: conduct current efficiently
- weak: conduct only small current
- non: no current flows

Types of Chemical Reactions ✔✔- combination: A + B → AB
- decomposition: AB → A + B
- combustion: AB + O₂ → AO(x) + BO(x)
- single displacement: AB + C → AC + B
- double displacement: AB + CD → AD + BC

1. Complete ionic equation
2. Net ionic equation ✔✔1. Ex: Ag+(aq) + NO₃-(aq) + Na+(aq) + Cl-(aq) → AgCl(s) +
Na+(aq) + NO₃-(aq)

2. Ag+(aq) + Cl-(aq) → AgCl(s)

Stoichiometry ✔✔the study of quantities of materials consumed and produced in
chemical reactions

steps to convert form mass of one reactant/product to another ✔✔1. given

, 2. molar mass of given
3. mole ratio between given and desired
4. molar mass of desired

Limiting Reagent ✔✔any reactant that is used up first in a chemical reaction which
determines the amount of product that can be formed in the reaction

percent yield ✔✔= (actual yield)/(theoretical yield) x 100%

1. Molarity
2. Molality
3. Mass percent ✔✔1. moles solute/liters solution (m/L)
2. moles solute/kg solvent
3. mass solute/mass solution
OR mass solvent/mass solution

Dilution ✔✔M1V1=M2V2

oxidation-reduction reaction (redox) ✔✔any chemical change in which one species is
oxidized (loses electrons) and another species is reduced (gains electrons)
OIL RIG

combustion ✔✔combining with oxygen

Boyle's Law ✔✔Pressure x Volume = constant
P1V1 = P2V2
inversely proportional

Charles' Law ✔✔at a constant pressure, volume of a fixed amount of gas is directly
proportional to its absolute temperature
V1/T1 = V2/T2

Avogadro's Law ✔✔for a gas at a constant temperature and pressure, volume is
directly proportional to number of moles of gas
V1/n1 = V2/n2

Ideal Gas Law ✔✔PV = nRT
equation of state of gas
R = proportionality constant =
0.08206 Lxatm/molxK

1 mole of any gas at STP ✔✔22.4 L

Density of a gas ✔✔d = PM/RT
M = molecular weight