Chemistry Answers

A. One mole each of compounds A and B reacts to give one mole each of products C and D, at 25 oC. The reaction is first-order with respect to A and first order overall.

i. What is the order with respect to reactant B?

ii. How will the rate of the reaction change when B’s concentration is doubled?

iii. Write the rate law for this reaction.

iv. Explain if this rate law is consistent with the reaction stated.

v. Define the term ‘half-life of a reactant’.

vi. Calculate the half-life of reactant A at 25 oC if the rate constant (k) at this temperature is 0.052 s-1 .

B. Explain how:

i. the rate of a chemical reaction can be determined graphically.

ii. a catalyst affects the rate of a chemical reaction.

iii. the surface area of reacting particles impact reaction rates.

A. State Le Chatelier’s Principle. (1 mark)

B. Explain how the presence of a catalyst affects a system at chemical equilibrium.(2 marks)

C. State the effect of increasing total pressure on the equilibrium conditions for a chemical equation that has:

i. more moles of gaseous products than gaseous reactants.

ii. more moles of gaseous reactants than gaseous products.

iii. the same number of moles of gaseous reactants and gaseous products. iv. all its reactants and products as pure solids and pure liquids.

D. For the Haber process N2(g) + 3H2(g) ⇌ 2NH3(g),

i. write the equilibrium expressions for Kc and Kp.

ii. calculate a value for Kc given that nitrogen and hydrogen are placed in an empty 5.00 dm3 container at 100 oC. When equilibrium is reached, the moles present are NH3 = 0.600 mol, N2 = 3.00 mol and H2 = 1.85 mol.

iii. write the relationship between Kc and Kp and use it to find a value for Kp at 100 oC, having determined a value for Kc at B ii. [R = 0.0821 (atm L)/(mol K)]. (5 marks)

A. Using the data booklet provided, complete the following tasks for the cell shown below: Ca (s) | Ca] 2+ (aq) || H+ (aq) | H2 (g) | Pt (s)

i. Identify the cathode and the anode. (2 marks)

ii. Write the standard half-cell equations. (4 marks)

iii. Write the overall balanced cell reaction and calculate the standard cell potential. (4 marks)

iv. Do a sketch of the cell. Write the half-cell reaction at each electrode. Indicate the standard cell properties, the direction of electron and ion flow as well as the identity of the electrolyte in the salt bridge. (10 marks)

(Total 20 marks)

Which compounds do ionic bond occur between elementary particles

Calculate the potential of a zinc electrode immersed in a solution in which the molar analytical concentration of Zn(NO3)2 is 4.00 ´ 1023, that for H2Y2- is 0.0550 M, and the pH is fixed at 9.00.