Chem. 123 Mid-Term 1, Version A

Chem. 123 mid-term 1, Version A

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Write the equations for the substitution reaction of n-bromobutane, a primary haloalkane, with the following reagents:

Draw the structures. (4 marks)

a)N(CH3)3

b)NaCN

Answer the following questions for this SN2 reaction: (6 marks)

CH3CH2CH2CH2Br + NaOH → CH3CH2CH2CH2OH + NaBr

a)What is the rate expression for the reaction?

b)What is the effect of doubling the concentration of n-butyl bromideon the rate of the reaction?

Give the major product that forms when (Z)-3-methyl-2-pentene reacts with: (4 marks)

a)HI

b)H2 in the presence of a platinum catalyst

Draw the structure of (2E)-4-methylpent-2-ene. (3 marks)

What is the relationship between the following compounds? (2 marks)

Is the molecule shown below chiral or achiral? Explain your answer. (2 marks)

Thiamphenicol (shown below) is an antibacterial agent; a) circle chiral carbon atom(s) on the structure. b) what is the hybridization of the numbered atoms.(4 marks)

What product results from the SN2 reaction between (R)-2-chloropentane

and hydroxide?(2 marks)

A) (R)-2-pentanol B) (S)-2-pentanol

C) racemic pentanol D) 1-pentanol

9. For the reaction, N2(g) + 3 H2(g) ↔2NH3(g) , the rate law would be: (2 marks)

A) First order B) Second order with regard to [NH3]

C) Third order D) not enough information to determine

For the first order reaction below(4 marks)

N2O5 (g) → 2 NO2 (g) + ½ O2 (g)

If t1/2= 22.5 h at 20◦ C and 1.5 hat 40◦C.

Calculate the activation energy of this reaction.

11. For the second order reaction A → products, the following data are obtained:(3 marks)

[A] = 3.024 M, t = 0 min

[A] = 2.935 M, t = 1.0 min

[A] = 2.852 M, t = 2.0 min

What is the rate constant, k? Show your work!

A) 3.6 × 10-3 M-1 min-1

B) 1.4 × 10-2 M-1 min-1

C) 2.2 × 10-2 M-1 min-1

D) 9.7 × 10-3 M-1 min-1

E) 1.0 × 10-2 M-1 min-1

Data for the reaction A + B → C are given below. (6 marks)

Experiment[A], M[B], MInitial rate, M/s

10.0300.0602.5 × 10-5

20.0300.0202.5 × 10-5

30.0600.06010.0 × 10-5

a)From the data given, determine the order of the reaction with respect to A and B.

b)What is the overall reaction order?

c)Write the rate equation and determine the value of the rate constant, k.

For the reaction PCl5 (g) ⇌ PCl3 (g) + Cl2 (g) Kc = 0.0454 at 261°C. If a vessel is filled with these gases such that the initial concentrations are [PCl5] = 0.2 M, [PCl3] = 0.20 M, and [Cl2] = 2.25 M, determine: (6 marks)

a)In which direction will a reaction occur and why?

b)What is the maximum concentration (M) of PCl5 at the equilibrium?

Which of the following keep the equilibrium position unchanged?(2 marks)

A) temperature decrease

B) concentration change

C) pressure change

D) homogeneous catalyst

15. Consider the reaction: (2 marks)

2SO2(g) + O2(g) ⇌ 2SO3(g) ΔH° = -196.6 kJ/mol

If the temperature is raised the equilibrium is displaced to which direction? Why?

Hydroxide ion is involved in the mechanism of the following reaction but is not consumed in the overall reaction. (4 marks)

OCl- + I- → OI- + Cl-

Show that the following mechanism is consistent with the rate law established for the following reaction:

Fast : OCl- + H2O HOCl + OH-

Slow: I- + HOCl → HOI + Cl-

Fast: HOI + OH- H2O + IO-

One of the reactions in the gasification of coal is

CO(g) + 3H2(g) ⇌ CH4(g) + H2O(g)ΔH° = -237 kJ

For each of the following changes, explain the effect (increase, decrease, no effect) on the number of moles of CH4(g) produced.(4 marks)

(a)increase the concentration of H2O(g

(b)decrease the volume of the container

(c)add a catalyst

(d) decrease the temperature