Question 1

Which of the following best describes the effect of a catalyst on the activation energy ($$E_a) of a $$chemical reaction?

Accepted Answer

A catalyst decreases the activation energy, making the reaction faster.

Question 2

Given the rate law $$ 	ext{rate} = k[	ext{A}]^2[	ext{B}] $$, what is the overall order of the reaction?

Accepted Answer

Third order

Question 3

Which of the following statements about dynamic equilibrium is correct?

Accepted Answer

At equilibrium, the rates of the forward and reverse reactions are equal.

Question 4

A reaction has a positive entropy change ($$ \Delta S \u003e 0 ) $$and a negative enthalpy change ($$ \Delta H \u003c 0 ). $$What can be said about the spontaneity of the reaction at all temperatures?

Accepted Answer

The reaction is spontaneous at all temperatures.

Question 5

Which of the following is the correct expression for the equilibrium constant $$K_c$$ for the reaction $$ \ce{2NO2(g)  N2O4(g)} $$?

Accepted Answer

$$ K_c = \frac{[\ce{N2O4}]}{[\ce{NO2}]^2} $$

Question 6

Which of the following best explains why increasing temperature generally increases the rate of a chemical reaction?

Accepted Answer

It increases the frequency of effective collisions between molecules.

Question 7

Which of the following is a correct statement about Le Chatelier's Principle?

Accepted Answer

If the pressure is increased on a system at equilibrium, the system shifts toward the side with fewer moles of gas.

Question 8

Which of the following is the correct formula for Gibbs free energy change?

Accepted Answer

$$ \Delta G = \Delta H - T\Delta S $$

Question 9

Which of the following is a correct statement about the effect of a common ion on the solubility of a sparingly soluble salt?

Accepted Answer

The presence of a common ion decreases the solubility of the salt.

Question 10

Which of the following best describes the difference between SN1 and SN2 mechanisms in organic chemistry?

Accepted Answer

SN1 reactions proceed via a carbocation intermediate, while SN2 reactions are concerted.

Question 11

A student mixes $$0.1$$ mol of acetic acid ($$\ce{CH3COOH}) $$with $$0.1$$ mol of sodium acetate ($$\ce{CH3COONa}) in$$ $$1 L of $$water. What type of solution is formed?

Accepted Answer

A buffer solution

Question 12

Which of the following is the correct IUPAC name for the compound $$\ce{CH3CH2COOH}$$?

Accepted Answer

Propanoic acid

Question 13

Which of the following statements about optical isomerism is correct?

Accepted Answer

Optical isomers rotate plane-polarized light in opposite directions.

Question 14

Which of the following is the correct structure for the enolate ion formed from acetone ($$\ce{CH3COCH3}) $$under basic conditions?

Accepted Answer

$$ \ce{CH2=C(O^-)CH3} $$

Question 15

Which of the following best describes the product of the reaction between an aldehyde and a primary amine?

Accepted Answer

An imine (Schiff base)

Question 16

Which of the following is a correct statement about the infrared (IR) absorption of a carbonyl group ($$\ce{C=O}$$)?

Accepted Answer

It absorbs strongly near $$1700\ 	ext{cm}^{-1}.$$

Question 17

Which of the following best explains why carboxylic acids have higher boiling points than alcohols of similar molecular mass?

Accepted Answer

Carboxylic acids form stronger hydrogen bonds due to dimerization.

Question 18

Which of the following is the correct product when benzene reacts with bromine in the presence of iron(III) bromide ($$\ce{FeBr3}$$)?

Accepted Answer

Bromobenzene ($$\ce{C6H5Br})$$

Question 19

Which of the following is the correct mechanism for the reaction of an alkene with $$\ce{HBr} in $$the presence of peroxides?

Accepted Answer

Free radical addition (anti-Markovnikov)

Question 20

Which of the following statements about the Diels-Alder reaction is correct?

Accepted Answer

It is a reaction between a diene and a dienophile to form a six-membered ring.

Comprehensive Overview of Organic Chemistry: Rates, Equilibria, and Advanced Topics

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