Although a reaction system may be at chemical equilibrium, the rate constants of the forward and reverse reactions will in general be different.

When 50.0 mL of 0.25 M methanoic acid, HCOOH, Ka = 1.8 × 10−4 is combined with 50.0 mL of 0.25 M hydrazine, a base, H2NNH2, Kb = 1.3 × 10−6, the resulting solution is:

A physical therapist assistant conducts an inservice on exercise guidelines for a group of senior citizens. As part of the inservice the physical therapist assistant discusses the benefits of improving cardiovascular status through a low intensity activity such as a walking program. What frequency of exercise would be the MOST desirable to achieve the stated objective?

Consider the following gas phase reaction: A(g) + B(g) ⇌ 2C(g)    Kp = 36 If initially 2.0 atm of A and 2.0 atm of B are placed in a chamber and then the reaction is allowed to proceed, calculate the equilibrium partial pressure of C.

Consider the acid ionization reaction of carbonic acid (H2CO3), which has a Ka of 3.98 × 10─7 H2CO3(aq) + H2O(l) ⇌ HCO3−(aq) + H3O+(aq) Which of the following will decrease the pH of the resulting solution? I. Addition of HCO3− II. Addition of H2CO3 III. Removal of HCO3−  

A chemist dissolves 324.mg of pure barium hydroxide in enough water to make up 90.mL of solution. Calculate the pH of the solution. (The temperature of the solution is 25°C)

Nitrous acid, HNO2, is a weak acid in water (pKa = 3.35). If an aqueous solution of nitrous acid with pH 2.69 is required, what concentration, in M, of the acid is needed? Enter your numerical answer to 4 decimal places and without units.

A chemical engineer is studying the following reaction: CH4(g) + 2H2S(g) → CS2(g) + 4H2(g) At the temperature the engineer picks, the equilibrium constant, Kp, for this reaction is 31. The engineer fills the reaction vessel with methane and hydrogen sulfide, and lets the reaction begin. He then measures the composition of the mixture inside each vessel from time to time. His first set of measurements show that there are 9.59 atm CH4, 6.70 atm H2S, 7.54 atm CS2, and 8.52 atm H2. Predict the changes in the compositions the engineer should expect next time he measures the compositions. Select all that apply.

Consider the equilibrium: CH4(g) + 2H2S(g) ⇌ CS2(g) + 4H2(g) In one experiment, 1.00 mol of CH4, 1.00 mol of CS2, 2.00 mol of H2S, and 2.00 mol on H2 are mixed in a 250-mL vessel at 960

The equilibrium constant, Kc, for the reaction PCl3(g) + Cl2(g) ⇌ PCl5 (g) is 49 at 230 ˚C. If 0.70 mol of PCl3 is added to 0.70 mol of Cl2 in a 1.00-L reaction vessel at 230 ˚C, what is the concentration, in mol/L, of PCl3 when equilibrium has been established? Enter a number, to 3 significant figures, and without units.