Question 1

Which of the following statements best describes the VSEPR theory and its application to molecular geometry?

Accepted Answer

VSEPR theory is used to predict the three-dimensional shape of molecules by minimizing the repulsion between electron pairs around a central atom.

Question 2

A student is analyzing a sample of hard water in a lab. Which chemical reaction is most likely being investigated to determine the hardness of the water?

Accepted Answer

The reaction of calcium ions with carbonate ions to form insoluble calcium carbonate: $$\mathrm{Ca$$^{2+}$$ + CO_3$^{2-} \rightarrow $$CaCO_3$$ (s)}$$

Question 3

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

Accepted Answer

Higher temperature increases the frequency and energy of collisions between reactant molecules, leading to more effective collisions.

Question 4

A solution of crystal violet is used in a kinetics experiment. The rate law for its fading is found to be first order with respect to crystal violet. Which equation correctly represents the integrated rate law for this reaction?

Accepted Answer

$$\ln [\mathrm{CV}] = -kt + \ln [\mathrm{CV}]_0$$

Question 5

During a calorimetry experiment, a student mixes 50.0 g of water at $$25.0\ ^\circ\mathrm{C}$$ with 50.0 g of water at $$75.0\ ^\circ\mathrm{C}. $$Assuming no heat is lost to the surroundings, what is the final temperature of the mixture?

Accepted Answer

$$50.0\ ^\circ\mathrm{C}$$

Question 6

Which of the following changes will shift the equilibrium of the reaction $$\mathrm{N_2$ (g) + 3H_2 (g) \rightleftharpoons 2NH_3 (g)} to $$the right, according to Le Chatelier’s principle?

Accepted Answer

Removing $$\mathrm{NH_3$} as it $$forms

Question 7

A student is performing a titration of a strong acid with a strong base. Which of the following best describes the pH at the equivalence point?

Accepted Answer

The pH is exactly 7 because the resulting solution contains only water and a neutral salt.

Question 8

Which of the following best describes the relationship between Gibbs free energy ($$\Delta G$$), enthalpy ($$\Delta H$$), and entropy ($$\Delta S) at $$constant temperature?

Accepted Answer

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

Question 9

Which of the following is a correct application of Beer’s Law in a laboratory setting?

Accepted Answer

Using the equation $$A = \varepsilon b c to $$determine the concentration of a colored solution by measuring its absorbance.

Question 10

A sample of $$0.50$$ mol of $$\mathrm{NaCl} is $$dissolved in $$500 mL of $$water. What is the molarity of the solution?

Accepted Answer

$$1.0\ \mathrm{M}$$

Question 11

Which of the following statements about the properties of solids is correct?

Accepted Answer

Metallic solids conduct electricity because of delocalized electrons.

Question 12

Which of the following best describes the process of dimensional analysis in stoichiometry?

Accepted Answer

Using conversion factors to systematically solve problems involving different units.

Question 13

In an electrochemical cell, which of the following statements is true?

Accepted Answer

Electrons flow from the anode to the cathode through the external circuit.

Question 14

A weak acid is titrated with a strong base. Which of the following best describes the shape of the titration curve?

Accepted Answer

The pH rises gradually at first, then sharply near the equivalence point, and the equivalence point is above pH 7.

Question 15

Which of the following is the correct expression for the equilibrium constant $$K_c$$ for the reaction $$\mathrm{2NO_2 (g) \rightleftharpoons N_2O_4 (g)}$$?

Accepted Answer

$$K_c = \frac{[N_2O_4]}{[NO_2$]^2}$$

Question 16

Which of the following best explains why ionic compounds tend to have high melting points?

Accepted Answer

They are held together by strong electrostatic attractions between oppositely charged ions.

Question 17

A reaction has $$\Delta H = -100\ \mathrm{kJ}$$ and $$\Delta S = -200\ \mathrm{J/K}. At $$what temperature (in K) does the reaction become non-spontaneous?

Accepted Answer

$$500\ \mathrm{K}$$

Question 18

Which of the following is a correct statement about mixtures?

Accepted Answer

Components of a mixture retain their individual properties.

Question 19

Which of the following best describes the purpose of a salt bridge in a galvanic cell?

Accepted Answer

To maintain electrical neutrality by allowing the flow of ions between the half-cells.

Question 20

A student designs a hand warmer using an exothermic reaction. Which of the following best explains why the hand warmer gets warm?

Accepted Answer

The reaction releases heat to the surroundings as products have lower enthalpy than reactants.

General Chemistry: Unit Overview and Study Guide

Guida di studio - Domande di pratica

Study guide - Flashcard