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General Chemistry Review
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General Chemistry Review
General Chemistry Review
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1
Question
What type of bonds are formed when two nonmetals share electrons?
Answer
Covalent bonds are formed between two nonmetals sharing electrons.
2
Question
How are ionic bonds formed between metals and nonmetals?
Answer
Ionic bonds are formed when a metal transfers electrons to a nonmetal and the resulting opposite charges attract each other.
3
Question
How does electronegativity difference affect bond polarity?
Answer
The greater the electronegativity difference between two atoms, the more polar the bond becomes.
4
Question
What are the typical products of a combustion reaction?
Answer
Combustion reactions produce carbon dioxide (CO₂) and water (H₂O).
5
Question
What is the empirical formula rhyme and what is it used for?
Answer
The rhyme is '% to mass, mass to mole, divide by small, times until whole' and it is used to find the simplest whole number ratio of moles (or atoms) in a compound to determine its empirical formula.
6
Question
How is the molecular formula related to the empirical formula of a compound?
Answer
The molecular formula is a whole number multiple of the empirical formula ratio.
7
Question
What determines the amount of product formed in a chemical reaction?
Answer
The limiting reactant determines the amount of product formed in a reaction.
8
Question
Why are gas mixtures considered homogeneous?
Answer
Because of the constant random motion of gas particles, gas mixtures are homogeneous.
9
Question
Explain the relationship between pressure (P) and volume (V) of a gas.
Answer
Pressure and volume are inversely related; doubling the volume of a container cuts the pressure of the gas in half.
10
Question
What is the ideal gas law and the units used for temperature, volume, and pressure?
Answer
The ideal gas law is PV = nRT, where temperature is in Kelvin, volume in liters, and pressure in atmospheres. The gas constant R = 0.08206.
11
Question
What conditions correspond to one mole of an ideal gas occupying 22.4 liters?
Answer
One mole of an ideal gas occupies 22.4 liters only at standard temperature and pressure (STP).
12
Question
Describe the general relationship between molar mass and molecular speed at a given temperature.
Answer
The greater the molar mass of a gas, the slower it moves at a given temperature.
13
Question
How does temperature relate to the kinetic energy of gas particles?
Answer
Temperature represents the average kinetic energy of gas particles; gases at the same temperature have the same average kinetic energy.
14
Question
What is lattice energy and how does it relate to ion charge and size?
Answer
Lattice energy is the energy required to break an ionic bond in a compound. It increases as the ion’s charge increases and decreases as the radii of the ions increase.
15
Question
How do intermolecular forces (IMFs) rank from weakest to strongest?
Answer
IMFs rank from weakest to strongest as: London dispersion, dipole-dipole, hydrogen bonding, and ion-dipole forces.
16
Question
What causes a molecule to be polar or nonpolar in terms of dipoles and molecular symmetry?
Answer
An asymmetrical molecule has dipoles that do not cancel, making it polar; a symmetrical molecule has dipoles that cancel, making it nonpolar.
17
Question
What is the difference between single, double, and triple covalent bonds in terms of sigma and pi bonds?
Answer
A single bond is a sigma bond; a double bond is one sigma plus one pi bond; a triple bond is one sigma plus two pi bonds.
18
Question
What is the formula to calculate the heat of reaction (ΔH_rxn)?
Answer
ΔH_rxn = Bonds broken − Bonds formed (reactant bonds are broken, product bonds are formed), or equivalently ΔH_rxn = ΔH_products − ΔH_reactants.
19
Question
What happens to ΔH when a reaction is doubled or reversed?
Answer
Doubling a reaction doubles ΔH; reversing a reaction changes the sign of ΔH.
20
Question
What are the bond angles and hybrid orbitals for molecules with 4, 3, and 2 electron domains?
Answer
4 domains: 109.5° angle, sp³ hybrid; 3 domains: 120° angle, sp² hybrid; 2 domains: 180° angle, sp hybrid.
21
Question
What determines the boiling and melting points of substances in relation to intermolecular forces?
Answer
Boiling and melting points increase as intermolecular forces (IMFs) increase.
22
Question
What are the characteristics of molecular solids versus ionic solids?
Answer
Molecular solids have low melting/boiling points and do not conduct electricity; ionic solids have high melting/boiling points, do not conduct electricity as solids but conduct when molten or aqueous.
23
Question
How do catalysts affect the rate of a chemical reaction?
Answer
Catalysts speed up reactions by lowering the activation energy, allowing more particles to react.
24
Question
How is the half-life of a first-order reaction calculated?
Answer
The half-life (t_1/2) of a first-order reaction is calculated as t_1/2 = 0.693 / k, where k is the rate constant.
25
Question
Explain Le Chatelier's Principle when Q > K_eq.
Answer
If the reaction quotient Q is greater than K_eq, the reaction shifts to the left, toward the reactants, to re-establish equilibrium.
26
Question
What is the relationship between pH, acids, and bases?
Answer
Acids have pH less than 7, bases have pH greater than 7; pure water has a pH of 7 at 25°C.
27
Question
What is the difference between strong acids and strong bases?
Answer
Strong acids fully ionize in solution (examples: HNO₃, H₂SO₄, HClO₄, HBr, HI, HCl), and strong bases fully ionize (Group 1 hydroxides, some Group 2 hydroxides, hydride, oxide, and nitride ions that produce OH⁻).
28
Question
How do you calculate pH from hydrogen ion concentration ([H⁺])?
Answer
pH = −log[H⁺]; conversely, [H⁺] = 10^(−pH).
29
Question
What does the strength of an acid imply about its conjugate base?
Answer
The stronger the acid, the weaker its conjugate base.
30
Question
How do you calculate the concentrations at equilibrium for a weak acid using the shortcut method?
Answer
[H⁺] = √(M_a × K_a), where M_a is the initial molarity of the acid and K_a is the acid dissociation constant, applicable only if the change is small relative to M_a.