Question 1

A chemical reaction in a hand warmer releases heat to the surroundings. Which of the following statements is TRUE regarding the enthalpy change ($$\Delta H) $$and the type of process?

Accepted Answer

The process is exothermic and $$\Delta H is $$negative.

Question 2

Which of the following molecules has a tetrahedral molecular geometry?

Accepted Answer

$$\mathrm{CH_4$}$$

Question 3

Which of the following best describes the change in entropy ($$\Delta S) $$for the system and surroundings when ice melts at room temperature?

Accepted Answer

The entropy of the system increases and the entropy of the surroundings decreases.

Question 4

Which of the following molecules is nonpolar?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 5

A system absorbs 150 J of heat from the surroundings and does 50 J of work on the surroundings. What is the change in internal energy ($$\Delta U) of $$the system?

Accepted Answer

$$\Delta U = 100\ \mathrm{J}$$

Question 6

Which of the following Lewis structures for $$\mathrm{$$ClO_3$$^-}$$ best minimizes formal charges?

Accepted Answer

A structure with one double bond and two single bonds to chlorine.

Question 7

Which of the following molecules contains a central atom with sp$$^3d$^2$$ hybridization?

Accepted Answer

$$\mathrm{SF_6$}$$

Question 8

Which of the following pairs of atoms forms a polar covalent bond?

Accepted Answer

C and F

Question 9

Which of the following statements is TRUE for a system that is doing work on the surroundings and losing heat to the surroundings?

Accepted Answer

$$q \u003c 0$$, $$w \u003c 0$$, $$\Delta U \u003c 0$$

Question 10

Which of the following molecules has the longest carbon–carbon bond length?

Accepted Answer

$$\mathrm{C_2H_6}$$

Question 11

Which of the following best describes the Lewis symbol for oxygen?

Accepted Answer

Six dots around the symbol O

Question 12

Which of the following molecules has a dipole moment?

Accepted Answer

$$\mathrm{H_2O}$$

Question 13

Which of the following is the correct bond order for the molecular ion $$\mathrm{H_2$^+}$$?

Accepted Answer

0.5

Question 14

Which of the following molecules contains a central atom with two lone pairs and two single bonds? What is its molecular geometry?

Accepted Answer

Bent

Question 15

Which of the following molecules contains a carbon–oxygen double bond?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 16

Which of the following best describes the electron geometry and molecular geometry of $$\mathrm{SF_4$}$$?

Accepted Answer

Electron geometry: Trigonal bipyramidal; Molecular geometry: Seesaw

Question 17

Which of the following is the correct formula for calculating the heat absorbed or released by a substance?

Accepted Answer

$$q = mC_s \Delta T$$

Question 18

Which of the following molecules has a linear molecular geometry?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 19

Which of the following is TRUE about the Lewis structure of $$\mathrm{NO_3$^-}$$?

Accepted Answer

It has three resonance forms.

Question 20

Which of the following best describes the hybridization of the central atom in $$\mathrm{CH_4$}$$?

Accepted Answer

sp$$^3$$

General Chemistry Exam 3 Study Guide: Thermochemistry, Chemical Bonding, and Molecular Geometry

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