Physical Chemistry Answers

A fuel cell is constructed in which both electrodes make use of the oxidation of methane. The left-hand electrode makes use of the complete oxidation of methane to carbon dioxide and liquid water; the right-hand electrode makes use of the partial oxidation of methane to carbon monoxide and liquid water. (a) Which electrode is the cathode? (b) What is the cell potential at 25 °C when all gases are at 1 bar?

Tabulated thermodynamic data can be used to predict the standard potential of a cell even if it cannot be measured directly. The standard Gibbs energy of the reaction K2CrO4(aq) + 2 Ag(s) + 2 FeCl3(aq) → Ag2CrO4(s) + 2 FeCl2(aq) + 2 KCl(aq) is −62.5 kJ mol−1 at 298 K. (a) Calculate the standard potential of the corresponding galvanic cell and (b) the standard potential of the Ag2CrO4/Ag,CrO42− couple.

Use the information in the Resource section to calculate the standard potential of the cell Ag(s)|AgNO3(aq)||Cu(NO3)2(aq)|Cu(s) and the standard Gibbs energy and enthalpy of the cell reaction at 25 °C. (ii) Estimate the value of ΔrG⦵ at 35 °C.

Calculate the standard potential of the cell Pt(s)|cystine(aq),

cysteine(aq)|| H+(aq)|O2(g)|Pt(s) and the standard Gibbs energy of the cell reaction at 25 °C. Use E⦵ = −0.34 V for cystine(aq) + 2 H+(aq) + 2 e− → 2 cysteine(aq).

Helium gas is contained inside a piston cylinder assembly as shown in the figure. Initially the gas is

having pressure 1 bar and volume 0.01 m3

. Then the current is supplied, and the gas is heated such

that the final pressure is 1.2 bar and the final volume is 0.0145 m3

. 10 % of the electrical energy

supplied to the gas is lost as heat from the cylinder. Determine the followings. If necessary, make

assumption(s) with justification.

(a) How long the current is supplied if process is ideal?

(b) How long the current is supplied if process is real?

1. Calculate the pH of the original buffer solution of dihydrogen phosphate/hydrogen phosphate.

2. Calculate the pH The 20 mL (dihydrogen phosphate/hydrogen phosphate buffer) solution when 1 mL of 0.1 molL-1 NaOH has been added

3. Calculate the pH of the 20 mL (dihydrogen phosphate/hydrogen phosphate buffer) solution when 1 mL of 0.1 molL-1 HCl has been added

- Using the Henderson formula for the pH of a solution: pH = pKa + log ([A-]/ [HA]), and show working out

Suggest reasons why a glass electrode can be used for the determination of the pH of an aqueous solution

a sample of air, upon analysis by an environmentalist showed that it contains 1.4x 10 of mercury per 50 ml of solution, what is the mercury concentration in a ppm chemistry answer

Increasing the temperature increases reaction rate because

A ) the activation energy of the reaction decreases (B)collision frequency increases C) Increases the rate of forward as well as backward reaction equally (Đ) all