Question 1

The Lewis structure shown in Image 1 represents which molecule, and what is the formal charge on the carbon atom?

Accepted Answer

Formaldehyde (CH2O), formal charge on C = 0

Question 2

Which of the following best describes the resonance structures shown in Image 2 for the carbonate ion ($$\mathrm{CO_3$^{2-}}$$)?

Accepted Answer

All three resonance structures have the same arrangement of atoms but different arrangements of electrons.

Question 3

What is the formal charge on each oxygen atom in the carbonate ion ($$\mathrm{CO_3$^{2-}}) as $$shown in Image 2?

Accepted Answer

One oxygen is 0, two are -1

Question 4

Based on the resonance structures of $$\mathrm{CO_3$^{2-}}$$, how does the bond length of the C–O bonds compare to typical single and double bonds?

Accepted Answer

The C–O bonds are all the same length, intermediate between a single and double bond.

Question 5

Refer to Image 3. At which point(s) is the substance undergoing a phase change, and what are the corresponding processes?

Accepted Answer

At points B–C (melting) and F–G (boiling)

Question 6

In the heating curve shown in Image 3, what is the physical state of the substance at point D?

Accepted Answer

Liquid

Question 7

According to the phase diagram in Image 4, what is the approximate temperature and pressure at the triple point?

Accepted Answer

$$\sim180 K $$and 0.01 atm

Question 8

In the phase diagram shown in Image 4, which region (color) represents the solid phase?

Accepted Answer

The light blue region on the left

Question 9

Which process is represented by the nearly vertical line at high pressure in the phase diagram (Image 4)?

Accepted Answer

Melting (solid to liquid)

Question 10

If the substance in Image 3 has a melting point at $$-17^{\circ}$$\mathrm{C}$$ and a boiling point at 68$$^{\circ}$$\mathrm{C}$$, what is the physical state at $$50^{\circ}$$\mathrm{C}$$?

Accepted Answer

Liquid

Question 11

For the molecule in Image 1, what is the molecular geometry around the central atom?

Accepted Answer

Trigonal planar

Question 12

Which of the following statements about the carbonate ion ($$\mathrm{CO_3$^{2-}}) is $$correct based on its resonance structures (Image 2)?

Accepted Answer

The actual structure is a hybrid with delocalized electrons.

General Chemistry Final Exam Review: Key Concepts and Problem-Solving Guidance

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