Reactions and Equilibrium - AP Chemistry

pOH would be 4 (use –log \[OH–\]) and pH would be 14–pOH = 14 – 4 = 10

\[OH-\] = 4 X 10-6

pOH = 5.4 — use –log \[OH–\] to find pOH

pH = 14– pOH = 8.6

NaOH is a base, so that won't produce an acidic solution. Of the remaining acids, HCl and HI are strong acids, and HF is weak. HI is at a higher molarity, so it will produce the most acidic solution.

The conjugate base of an acid will be the same compound, short one H atom. ClO4– is the only one that meets this criterion.

A Lewis base is an electron-pair donor. Only PH3 has a pair of nonbonding electrons and can act as a donor.

The conjugate base has one less H atoms and one unit greater negative charge because of this. Thus, the correct answer is HC2O4–

This question is simply testing your memorization of strong and weak acids. Of the list, you should recognize that nitric acid is the only strong acid, and the rest of the choices are weak.

To answer this question we need to look at the reaction below:

An increase in the pH will result in a decrease in the concentration of hydrogen ions (). Using Le Chatelier’s principle we can find out which answer choices will decrease .

Removing carbonic acid will decrease the concentration of . To maintain equilibrium, the reaction will shift to the left and make more reactants from products; therefore, there will be a decrease in the and an increase in pH.

Recall that salts like sodium bicarbonate, or , will dissociate in water and form ions. Sodium bicarbonate will form sodium () and bicarbonate () ions. This side reaction will result in an increase in the bicarbonate ion concentration. Le Chatelier’s principle will shift the equilibrium of the given reaction to the left and, therefore, decrease the . Adding sodium bicarbonate will increase the pH.

Acid strength of an oxy acid increases with increasing electronegativity on the halogen.

For an oxyacid, the acid strength increases as the number of oxygens increase.

The correct answer gives the accurate definition of both the equilibrium constant and the reaction quotient.

According to the law of mass action, the equilibrium constant expression can always be written given the equation of the reaction itself. The equilibrium-constant expression will be written as the products over the reactants, each raised to their respectively stoichiometric coefficient. The rate law and concentrations can only be determined if there is additional data given.

Equilibrium expressions are specific for certain temperatures. Physical state, pressure, and volume do not factor into the expression.

Based on the balanced equation, one would use -x, -2x, and +x.

According to Le Chatelier's principle, any changes in concentration or pressure to a system at equilibrium will cause the system to readjust to a new equilbrium. The addition of a reactant will cause the reaction to shift to the right, increasing the equilibirum concentration of the products. Thus, adding additional reactant A would increase the equlibrium concentration of product C.

Removing species A or adding species E will drive the reaction to the left, reducing the amount of species C. Since the reaction is exothermic, heat can be considered a product. Thus, increasing the temperature will also shift the reaction to the left.