Q: Given the following thermodynamic data (see image 12): 2ZnS(s) + 3O2(g) → 2ZnO(s) + 2SO2(g), calculate the standard enthalpy change (ΔH°) for the reaction.

$$\Delta H^\circ = [2 \times (-348.3) + 2 \times (-296.8)] - [2 \times (-205.6) + 3 \times 0] = -892.6\ \text{kJ}$$

Q: Using the bond enthalpy table (image 14), estimate the enthalpy change (ΔH) for the reaction: CH$$_4(g) + 2Cl$_2(g$$) → CCl$$_4(g) + 2H$_2(g).$$

$$\Delta H = [4 \times 413 + 2 \times 243] - [4 \times 327 + 2 \times 436] = -144\ \text{kJ}$$

Question 1

Refer to the phase diagram shown in the first image. Which statement about this diagram is NOT true?

Accepted Answer

Increasing pressure at constant temperature can cause liquid to freeze.

Question 2

In the phase diagram shown, what does point A represent?

Accepted Answer

The triple point, where solid, liquid, and gas phases coexist in equilibrium.

Question 3

Refer to the reaction coordinate diagram in the third image. Which of the following is NOT true?

Accepted Answer

D represents activation energy; E represents ΔH for the reaction.

Question 4

Which titration curve (images 4–7) best represents the titration of a strong acid (e.g., HCl) with a strong base (e.g., KOH)?

Accepted Answer

Image 4

Question 5

Which titration curve (images 8–11) best represents the titration of a weak acid (e.g., HF) with a strong base (e.g., KOH)?

Accepted Answer

Image 11

Question 6

Given the following thermodynamic data (see image 12): 2ZnS(s) + 3O2(g) → 2ZnO(s) + 2SO2(g), calculate the standard enthalpy change (ΔH°) for the reaction.

Accepted Answer

$$\Delta H^\circ = [2 	imes (-348.3) + 2 	imes (-296.8)] - [2 	imes (-205.6) + 3 	imes 0] = -892.6\ 	ext{kJ}$$

Question 7

Using the bond enthalpy table (image 14), estimate the enthalpy change (ΔH) for the reaction: CH$$_4(g) + 2Cl$_2(g$$) → CCl$$_4(g) + 2H$_2(g).$$

Accepted Answer

$$\Delta H = [4 	imes 413 + 2 	imes 243] - [4 	imes 327 + 2 	imes 436] = -144\ 	ext{kJ}$$

Question 8

Refer to the reaction coordinate diagram (image 15). What does the arrow labeled 'a' represent?

Accepted Answer

The activation energy for the forward reaction.

Question 9

Using the standard reduction potentials table (image 16), which of the following is the best oxidizing agent in 1 M solutions?

Accepted Answer

Ag$$^{+}(aq)$$

Question 10

Using the standard reduction potentials table (image 16), which of the following metals is most easily oxidized?

Accepted Answer

Zn

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