Q: A 50.0 g sample of water is heated from $$25.0\ ^\circ\mathrm{C} to$$ $$75.0\ ^\circ\mathrm{C}. If $$the specific heat capacity of water is $$4.18\ \mathrm{J/g\cdot K}$$, how much heat is absorbed by the water?

$$1.05 \times 10^4$\ \mathrm{J}$$

Question 1

Which of the following statements best describes an endothermic process?

Accepted Answer

A process in which energy is absorbed from the surroundings as heat.

Question 2

A 50.0 g sample of water is heated from $$25.0\ ^\circ\mathrm{C} to$$ $$75.0\ ^\circ\mathrm{C}. If $$the specific heat capacity of water is $$4.18\ \mathrm{J/g\cdot K}$$, how much heat is absorbed by the water?

Accepted Answer

$$1.05 	imes 10^4$\ \mathrm{J}$$

Question 3

Which of the following molecules is expected to have the highest boiling point?

Accepted Answer

$$\mathrm{H_2O}$$

Question 4

Given the reaction: $$2\mathrm{H_2$}(g) + \mathrm{O_2$}(g) \rightarrow 2\mathrm{H_2O}(l)$$, $$\Delta H = -571.6\ \mathrm{kJ}. $$How much heat is released when $$4.00\ \mathrm{g} of$$ $$\mathrm{H_2$}$$ reacts with excess $$\mathrm{O_2$}$$?

Accepted Answer

$$-566\ \mathrm{kJ}$$

Question 5

Which of the following best explains why $$\mathrm{NH_3$}$$ has a higher boiling point than $$\mathrm{PH_3$}$$?

Accepted Answer

Ammonia forms hydrogen bonds, which are stronger than the dipole-dipole interactions in phosphine.

Question 6

What is the hybridization of the central carbon atom in $$\mathrm{CO_2$}$$?

Accepted Answer

$$sp$$

Question 7

Which of the following statements about the enthalpy change $$\Delta H$$ for a chemical reaction is correct?

Accepted Answer

$$\Delta H is $$the heat absorbed or released at constant pressure.

Question 8

Which of the following molecules has a linear molecular geometry?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 9

A sample of $$\mathrm{N_2$}$$ gas occupies $$2.50\ \mathrm{L} at$$ $$25.0\ ^\circ\mathrm{C}$$ and $$1.00\ \mathrm{atm}. $$What will be its volume at $$50.0\ ^\circ\mathrm{C}$$ and $$1.00\ \mathrm{atm}$$?

Accepted Answer

$$2.71\ \mathrm{L}$$

Question 10

Which of the following is the best Lewis structure for $$\mathrm{$$OCl_2$$}$$?

Accepted Answer

O with two single bonds to Cl, and two lone pairs on O, each Cl with three lone pairs

Question 11

Which of the following molecules has the greatest London dispersion forces?

Accepted Answer

$$\mathrm{C_6H_{14}}$$

Question 12

Which of the following is a correct statement about the relationship between $$\Delta H$$ and $$\Delta U$$ for a reaction in which the number of moles of gas changes?

Accepted Answer

$$\Delta H = \Delta U + \Delta n_gRT$$

Question 13

Which of the following molecules is nonpolar?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 14

Which of the following molecules has a bond angle closest to $$109.5^\circ$$?

Accepted Answer

$$\mathrm{CH_4$}$$

Question 15

Which of the following is the correct order of decreasing F–C–F bond angle in the compounds below?
I. $$\mathrm{BF_2Cl}
II$$. $$\mathrm{BF_3$}$$
III. $$\mathrm{CF_2Cl_2}$$

Accepted Answer

II \u003e I \u003e III

Question 16

Which of the following molecules is expected to be paramagnetic?

Accepted Answer

$$\mathrm{O_2$}$$

Question 17

Which of the following molecules can form hydrogen bonds with water?

Accepted Answer

$$\mathrm{CH_3OH}$$

Question 18

Which of the following is the maximum number of $$\sigma$$ bonds that can be formed between two atoms?

Accepted Answer

1

Question 19

Which of the following is the correct hybridization for the central atom in $$\mathrm{NH_3$}$$?

Accepted Answer

$$sp^3$$

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