Honors Chemistry Review Flashcards

A set of flashcards based on key concepts and definitions from the Honors Chemistry lecture notes.

What is the rule for rounding when multiplying or dividing numbers in chemistry?

Round based on the smallest number of significant figures in the original numbers.

How should you round when adding or subtracting numbers?

Round based on the smallest number of decimal places in the original numbers.

What are the rules for significant zeros?

Leading zeros are not significant, trapped zeros are significant, trailing zeros with decimal are significant, trailing zeros without decimal are not significant.

What is the principle of dimensional analysis?

It's a method used throughout the year to ensure proper unit conversions.

Does mass change during chemical and physical changes?

No, mass is conserved.

How can compounds and mixtures be separated?

Compounds can be separated by chemical changes, mixtures can be separated by physical changes.

What does filtering do?

It separates mixtures based on differences in particle size; large particles are trapped on the filter, while soluble components pass through.

How does distillation work?

It separates mixtures based on differences in boiling points.

What is chromatography used for?

To separate mixtures based on differences in polarity.

How do you read a graduated cylinder correctly?

Always read from eye level.

How do you estimate volume using a graduated container?

By reading in between the graduated markings for more significant figures.

What is the formula for density?

Density = mass/volume.

What distinguishes isotopes from ions?

Isotopes have different numbers of neutrons, while ions have different numbers of electrons.

What did Rutherford's Gold Foil Experiment discover?

It discovered the dense, positively charged nucleus and that the atom is mostly empty space.

What does the Aufbau principle state about electron filling?

Fill lowest energy orbitals first.

What are the main types of chemical reactions?

Synthesis, decomposition, single replacement, double replacement, combustion.

What is the molar mass?

It is the sum of each atom in the formula expressed in g/mol.

How do you calculate percent yield?

% yield = (experimental / theoretical) x 100.

What is the Ideal Gas Law equation?

PV = nRT.

What does the Le Chatelier’s Principle state?

A system at equilibrium will shift to lessen the effect of an applied stressor.

What is the reaction of an acid with a base?

Acid + Base → H2O + a salt.

What is oxidation?

The loss of electrons.

What is the equivalence point in titration?

It is where the moles of acid equal the moles of base.

What is activation energy?

Activation energy is the minimum energy required for particles to collide and break bonds, often visualized as the height of the 'hill' in a reaction profile.

How do you write a rate law for an elementary step?

For an elementary step such as 2A + B → C + D, the rate law is Rate = k[A]^2[B]^1.

What are the units of the rate constant (k) for different reaction orders?

0th order: Ms^-1, 1st order: s^-1, 2nd order: M^-1 s^-1.

What is the graphical representation for first and second order reactions?

1st order reactions are linear when plotting ln[A] versus time, while 2nd order reactions are linear when plotting 1/[A] versus time. The absolute value of the slope equals k.

What are the ways to speed up a reaction?

1. Add a catalyst to lower activation energy.
2. Increase reactant concentration.
3. Increase surface area for more collisions.
4. Increase pressure of gases for more collisions.
5. Increase temperature to increase collision frequency and activation energy.

What is the half-life formula for different order processes?

0th order: t1/2 = [A]0/2k; 1st order: t1/2 = 0.693/k; 2nd order: t1/2 = 1/k[A]0.

How does the half-life of a 1st order reaction behave?

The half-life of a 1st order reaction remains constant regardless of the initial concentration.

What is the relationship between activation energy and reaction speed?

The taller the 'hill' of activation energy, the slower the reaction.

What is the slow step (rate-determining step) in a reaction mechanism?

The rate-determining step is the slowest step that dictates the overall speed of the reaction and determines the rate law.

What are intermediates in reaction mechanisms?

Intermediates are species produced in one step of a reaction mechanism and consumed in a subsequent step.

How are catalysts used in reaction mechanisms?

Catalysts are used in an early step of a reaction mechanism and are regenerated in a later step.

Do catalysts shift an equilibrium?

No, catalysts do not shift an equilibrium; they only increase the rate at which equilibrium is reached.

Do inert gases affect equilibrium?

No, inert gases do not shift an equilibrium because they do not react with the substances involved in the equilibrium.

What phases appear in an equilibrium expression?

Only aqueous (aq) and gaseous (g) phases appear in an equilibrium expression.

What is the notation used for molarity and gas pressure in equilibrium expressions?

Use [A] for molarity (concentration in mol/L) and P_gas for pressure in atm.

What do mass spectroscopy graphs measure?

Mass spectroscopy graphs measure the atomic masses of isotopes.

What happens to atomic radius and ionization energy as you move across a row in the periodic table?

As you move across a row in the periodic table, the effective nuclear charge (Z_eff) increases, attracting valence electrons more strongly, which decreases atomic radius and increases ionization energy.

How are covalent bonds formed?

Covalent bonds are formed between two nonmetals that share electrons.

How are ionic bonds formed?

Ionic bonds are formed when a metal transfers electrons to a nonmetal, resulting in opposite charges that attract each other.

What effect does electronegativity difference have on bond polarity?

The greater the electronegativity difference between two atoms, the more polar the bond becomes.

What is the significance of asymmetrical and symmetrical molecules in terms of polarity?

Asymmetrical molecules have dipoles that do not cancel, making them polar; symmetrical molecules have dipoles that cancel, making them nonpolar.

What are the types of bonds and their characteristics?

Single bond = sigma bond; double bond = sigma + pi bond; triple bond = sigma + 2 pi bonds.

What is lattice energy?

Lattice energy is the energy required to break an ionic bond in a compound, increasing with ion charge and decreasing with increasing ion radius.

How does formal charge work in Lewis structures?

Formal charge involves comparing the number of valence electrons an atom has with the number of electrons around it in the Lewis structure, splitting bonded electrons evenly between atoms.

What rule should be obeyed when drawing Lewis Dot Structures?

Obey the octet rule first, then use formal charge if necessary. Extra electrons can go on the larger central atom, and if there are too few electrons, create double or triple bonds.

Why are gas mixtures considered homogeneous?

Gas mixtures are homogeneous because of the constant random motion of the particles.

Why are gases compressible?

Gases are compressible due to the large spaces between the particles.

What causes gas pressure?

Gas pressure is caused by the collisions of particles with the walls of the container; more collisions result in more pressure.

What is the relationship between pressure and volume (P and V)?

Pressure and volume are inversely related; doubling the volume of a container will cut the pressure of the gas in half.

What is the relationship between temperature and volume (T and V)?

Temperature and volume are directly related; if you heat a balloon, it will expand.

What is the relationship between temperature and pressure (T and P)?

Temperature and pressure are directly related; if you heat a rigid container, the pressure of the gas will increase.

What is the ideal gas law equation?

The ideal gas law is expressed as PV=nRT, where R=0.08206.

What are the units for temperature, volume, and pressure in gas law calculations?

Temperature is in Kelvin, volume is in Liters, and pressure is in atm.

What is the volume of one mole of an ideal gas at STP?

One mole of an ideal gas occupies 22.4 Liters ONLY at STP.

How do gas pressure and the number of moles relate?

Gas pressure and the number of moles are directly related; doubling the number of moles of gas in a container will double the pressure.

What is the formula for calculating molar mass of a gas?

Molar Mass = dRT/P, where 'd' stands for density in g/L.

How does molar mass affect the speed of gas molecules?

The more molar mass a gas has, the slower it moves at a given temperature.

What does temperature represent in relation to kinetic energy of gases?

Temperature equals the average kinetic energy; gases at the same temperature have the same average kinetic energy.

What is the equation used when collecting a gas by water displacement?

Ptotal = Pdry gas + P_water vapor.

Under what conditions do real gases behave most like ideal gases?

Real gases behave most like ideal gases at high temperatures and low pressures; small, nonpolar gases are the most ideal.

What is the order of intermolecular forces from weakest to strongest?

The order of intermolecular forces from weakest to strongest is: London Dispersion, dipole-dipole, hydrogen bonding, ion-dipole.

What are London Dispersion forces, and how do they change with molecule size?

London Dispersion forces are present in all molecules and become stronger as the molecule is larger; a larger electron cloud leads to more polarizability.

Which molecules possess dipole-dipole forces?

All polar molecules possess dipole-dipole forces, and the strength increases with the polarity of the molecule.

What are hydrogen bonds, and between which atoms do they occur?

Hydrogen bonds occur between nitrogen, oxygen, or fluorine (NOF) in one compound and hydrogen that is already bonded to NOF in another compound.

How do boiling and melting points correlate with intermolecular forces?

Boiling point and melting point increase as intermolecular forces (IMFs) increase.

How does vapor pressure and volatility relate to intermolecular forces?

Vapor pressure and volatility decrease as intermolecular forces increase.

What are the characteristics of molecular solids?

Molecular solids have low melting/boiling points and do not conduct electricity.

What are the properties of ionic solids?

Ionic solids have high melting/boiling points, do not conduct electricity as solids, but do conduct as liquids or in aqueous solution.

What are covalent network solids, and what are some examples?

Covalent network solids, such as SiO2 (quartz) and diamonds (C), have very high boiling/melting points.

What are metallic bonds, and how do they conduct electricity?

Metallic bonds occur between metals, and they always conduct electricity; their hardness varies.

What happens to intermolecular forces when a molecular solid melts or boils?

When a molecular solid melts or boils, it is the intermolecular forces between the molecules that break, not the covalent bonds.

What are interstitial and substitutional alloys?

Interstitial alloys are formed when a smaller atom fits into gaps between larger atoms in a metallic crystal; substitutional alloys occur when metals of similar radius substitute into the crystal lattice.

What does buffer capacity depend on?

Buffer capacity depends on the concentration of the components in the buffer solution.

How does acidity relate to the size of cations?

Smaller cations are more acidic because they have a higher charge density, which can stabilize the negative charge on anions.

What effect does charge on a cation have on acidity?

More positive charge on the cation makes it more acidic due to stronger attraction to negative ions.

How does the presence of electronegative atoms in an anion affect acidity?

More oxygens or more electronegative atoms on an anion makes it more acidic, as they can stabilize negative charges better.

What are two factors that can make a cation more acidic?

1) The size of the cation (smaller is more acidic), 2) The positive charge on the cation (more positive charge increases acidity).

What are the two general components of a buffer?

1) A weak acid, 2) Its conjugate base.

What does MaKa/[salt] equal?

MaKa/[salt] equals the concentration of hydrogen ions, [H+].

What units can be used instead of molarity for Ma and [salt] when calculating [H+]?

You can use millimolar (mM) instead of molarity.

What happens to the % ionization of a weak acid when a common ion is added?

Adding a common ion to a weak acid decreases the % ionization.

What effect do common ions have on the pH of a weak acid/base?

Adding a common ion to a weak acid/base will generally decrease the pH.

What is the condition for MaVa=MbVb to be true in a titration?

This equation is true at the equivalence point of a titration.

What type of calculation is M1V1 = M2V2 used for?

M1V1 = M2V2 is used for dilution calculations.

At the equivalence point of a weak acid + strong base titration, what is the pH?

The pH at the equivalence point is above 7.

At the equivalence point of a weak base + strong acid titration, what is the pH?

The pH at the equivalence point is below 7.

At the equivalence point of a strong acid + strong base titration, what is the pH?

The pH at the equivalence point is equal to 7.

At what point in a titration is pH equal to pKa?

pH = pKa at the ½ equivalence point during a titration.

What two concentrations are equal at the ½ equivalence point for a weak + strong titration?

At the ½ equivalence point, the concentrations of the weak acid and its conjugate base are equal.

What does the pKa equal at the ½ equivalence point for a weak + strong titration?

At the ½ equivalence point, pKa equals pH.

What does the magnitude of Ksp indicate about a salt?

The magnitude of Ksp indicates the solubility of the salt; a larger Ksp means the salt is more soluble.

Will a precipitate form when the reaction quotient Q is greater than Ksp?

A precipitate will form when Q is greater than Ksp.

What are common spectator ions in a chemical reaction?

Common spectator ions include Na^+, K^+, and Cl^−.

How do you choose an appropriate indicator for a titration?

Choose an indicator with a pKa close to the pH at the equivalence point of the titration.

When does hydrogen NOT have a +1 oxidation number?

Hydrogen has a -1 oxidation number in hydrides, where it is bonded to metals.

When does oxygen NOT have a -2 oxidation number?

Oxygen has a -1 oxidation number in peroxides.