Question 1

Which of the following best describes the difference between a sigma ($$\sigma) $$bond and a pi ($$\pi) $$bond in valence bond theory?

Accepted Answer

A $$\sigma$$ bond is formed by the end-to-end overlap of orbitals along the internuclear axis, while a $$\pi$$ bond is formed by the side-to-side overlap of parallel $$p$$ orbitals above and below the internuclear axis.

Question 2

A 0.250 L sample of Solution A containing an unknown concentration of hydrochloric acid (HCl) is titrated with 0.100 M NaOH. If the titration requires 12.5 mL of 0.100 M NaOH to reach the endpoint, what is the molarity of HCl in Solution A?

Accepted Answer

$$0.0500\ \mathrm{M}$$

Question 3

Which of the following compounds is expected to be soluble in water?

Accepted Answer

KNO$$_3$$

Question 4

Which of the following is a correct balanced molecular equation for the reaction between aqueous magnesium chloride and aqueous sodium carbonate to produce solid magnesium carbonate?

Accepted Answer

$$\mathrm{$$MgCl_2$$(aq) + Na_2CO_3(aq) \rightarrow $$MgCO_3$$(s) + 2NaCl(aq)}$$

Question 5

A gas has a density of $$1.41\ \mathrm{g/L} at a $$temperature of $$21^\circ\mathrm{C}$$ and a pressure of $$0.980\ \mathrm{atm}. $$What is the molar mass of the gas?

Accepted Answer

$$34.8\ \mathrm{g/mol}$$

Question 6

Which of the following species has unpaired electrons according to molecular orbital theory?

Accepted Answer

$$\mathrm{O_2$}$$

Question 7

Which of the following is NOT an electrolyte?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} ($$glucose)

Question 8

Which of the following reactions is a precipitation reaction?

Accepted Answer

$$\mathrm{Mg(NO_3$)_2(aq) + Na_2CO_3(aq) \rightarrow $$MgCO_3$$(s) + 2NaNO_3(aq)}$$

Question 9

A sample of gas occupies $$2.50\ \mathrm{L} at$$ $$1.00\ \mathrm{atm}$$ and $$24.0^\circ\mathrm{C}. $$How many moles of gas are present?

Accepted Answer

$$0.102\ \mathrm{mol}$$

Question 10

Which of the following best explains why real gases deviate from ideal gas behavior at high pressures and low temperatures?

Accepted Answer

Intermolecular forces between gas particles become significant, and the volume occupied by the particles themselves cannot be ignored.

Question 11

Which of the following is the limiting reactant when 16.1 grams of Mg(OH)$$_2$$ are mixed with 17.8 grams of HCl in the reaction $$\mathrm{Mg(OH)_2 + 2HCl \rightarrow $$MgCl_2$$ + 2H_2O}$$?

Accepted Answer

HCl

Question 12

Which of the following molecules has the largest bond angle?

Accepted Answer

CH$$_4$$

Question 13

What is the oxidation number of sulfur in the compound SO$$_4$$^{2-}$$?

Accepted Answer

$$+6$$

Question 14

Which of the following best describes the molecular geometry of ammonia (NH$$_3$$)?

Accepted Answer

Trigonal pyramidal

Question 15

A solution is prepared by dissolving 43.4 g of NaCl in enough water to make 1.00 L of solution. What is the molarity of the solution?

Accepted Answer

$$0.743\ \mathrm{mol/L}$$

Question 16

Which of the following statements about hybridization is correct?

Accepted Answer

The nitrogen atom in ammonia (NH$$_3) is$$ $$sp^3$$ hybridized.

Question 17

Which of the following gases will effuse most rapidly under identical conditions?

Accepted Answer

H$$_2$$

Question 18

Which of the following is a redox reaction?

Accepted Answer

$$\mathrm{Zn(s) + 2HCl(aq) \rightarrow $$ZnCl_2$$(aq) + H_2$(g)}$$

CHEM 111 Exam 3 Study Guide: Concepts and Skills from Chapters 6, 7, 8, and 10

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