The Cr₂O₇^2-(aq) gains electrons to change the oxidation state on Cr from +6 to +3. The Ni(s) loses electrons to change the oxidation state on Ni from 0 to +2.

In phase I, an increased temperature means the molecules are moving faster and will spread out more, leading to an increased volume. For the volume to remain constant in phase II, either both pressure and volume have to remain constant, or they both have to increase or decrease together, as they are inversely proportional.

Water is polar, and using "like dissolves like," we know that only polar solvents will be able to fully mix with it to create a homogenous solution.

Between trial 1 and 3, the concentration of NO doubled while the concentration of Br₂ held constant, and the rate went up by a factor of four. So, the reaction is second order with respect to NO. Between trial 1 and 2, the concentration of NO was held constant while the concentration of Br₂ doubled, and the rate went up by a factor of two. Thus, the reaction is first order with respect to Br₂.

Distillation involves the boiling off of substances with different boiling points. The other three compounds are all ionic, meaning that in solution they are free ions. If we were to boil off all of the N₂H₄ and the water, the remaining ions would all mix together to form multiple precipitates. However, by heating the solution to a boiling point greater than that of N₂H₄ and lower than that of water, the N₂H₄ can be collected in a separate flask.

14.0 g of Si is 0.50 mol, and 32.0 g of oxygen is 2.0 mol. Converting that to a whole number ratio gives us 1 mol of Si for every 4 moles of O.

Adding (or removing) any species in an equilibrium reaction does not change the equilibrium constant and also does not change the magnitude of the Gibbs free energy at standard conditions.

In one mole of dichromate, two moles of chromium are reduced, each requiring three moles of electrons. Three moles of nickel are being oxidized, each requiring two moles of electrons. Thus, six moles of electrons are being transferred.

The precipitate is PbCl₂, and in every mole of precipitate there are two moles of chlorine ions. Thus, there are 0.010 mol of chlorine present in the precipitate, and through conservation of mass, the same number of moles of chlorine were present in the original sample. 0.010 mol × 35.5 g = 0.355 g

Except for CO₂, the other three molecules all display resonance.

The farther away an electron is from the nucleus, the less ionization energy that is required to eject it, and as a result, the electron will have more kinetic energy after it is ejected. The 3p subshell is the farthest one that a neutral chlorine atom would have electrons in. Beware of choice (D); chlorine does not have a 3d subshell.

Strong acids and bases do not make good buffers, so that eliminates (A) and (D). Of the remaining choices, a solution of H₂PO₄^- would with a K_a in the 10^-13 range would have a [H⁺] of . That would put [H⁺] between 10^-6 and 10^-7, yielding a pH in the required range.

All three of those structures have three electron domains, and thus sp² hybridization.

Temperature in Kelvins is a measure of kinetic energy. When that temperature doubles, so does the kinetic energy. However, a doubling of the temperature in Celsius, while increasing the amount of kinetic energy, would not double it.

The addition of a catalyst speeds up the reaction but will not affect the enthalpy or the entropy values.

One way to calculate enthalpy is by subtracting the strength of the bonds broken in the reactants from the strength of the bonds formed in the products. If the first value is greater than the second value, the overall enthalpy change will be negative.

The bonds between HF molecules are hydrogen bonds, which are very strong dipoles created due to the high electronegativity value of fluorine. No other hydrogen halide exhibits hydrogen bonding, and thus they would have weaker intermolecular forces (and lower boiling points) than HF.

Weak acids resist changes in pH more effectively than strong acids because so many molecules of weak acid are undissociated in solution. The base must cause those molecules to dissociate before affecting the pH significantly.

Both are nonpolar, but propane has a lot more electrons and thus is more polarizable than ethene.

The outermost s-block electrons in a transition metal tend to be lost before the d-block electrons do. Additionally, the other options do not accurately describe the properties of transition metals.

London dispersion forces are created by temporary dipoles due to the constant motion of electrons in an atom or molecule.

The following Lewis structures are necessary to answer questions 38-41:

CO₂ has a bond order of 2, which exceeds the order of the other structures. Remember that a higher bond order corresponds with shorter and stronger

An ionic substance would dissolve in water, and a nonpolar covalent substance would have a low melting point. A metallic substance would be a good conductor. The only type of bonding that meets all the criteria is covalent network bonding.

Even if this were true, any pathways that become available at higher temperatures would be less likely to be taken than the original pathway.

Using M₁V₁ = M₂V₂, we can calculate the amount of stock solution needed. (12.0)V₁ = (4.0)(100.0), so V₁ = 33.3 mL. When making solutions, always add acid to water (in order to more effectively absorb the heat of the exothermic reaction).