Q: A sample of gas occupies 2.50 L at 1.00 atm and 300 K. If the pressure is increased to 2.00 atm and the temperature is decreased to 150 K, what will be the new volume of the gas? (Assume ideal gas behavior.)

$$V_2$$ = $$V_1$$ \times \frac{$$P_1$$}{$$P_2$$} \times \frac{$$T_2$$}{$$T_1$$} = 2.50\,\text{L} \times \frac{1.00}{2.00} \times \frac{150}{300} = 0.625\,\text{L}$$

Q: A solution is prepared by dissolving 5.85 g of NaCl in enough water to make 500 mL of solution. What is the molarity of the solution? ($$\mathrm{NaCl}$$ molar mass = 58.5 g/mol)

$$M = \frac{\text{moles}}{\text{liters}} = \frac{5.85/58.5}{0.500} = 0.2\,\mathrm{mol/L}$$

Question 1

Which of the following statements best explains why sodium (Na) is more reactive than magnesium (Mg) when exposed to water, based on their positions in the periodic table?

Accepted Answer

Sodium has a lower ionization energy than magnesium, so it loses its outer electron more easily.

Question 2

A sample of gas occupies 2.50 L at 1.00 atm and 300 K. If the pressure is increased to 2.00 atm and the temperature is decreased to 150 K, what will be the new volume of the gas? (Assume ideal gas behavior.)

Accepted Answer

$$V_2$$ = $$V_1$$ 	imes \frac{$$P_1$$}{$$P_2$$} 	imes \frac{$$T_2$$}{$$T_1$$} = 2.50\,	ext{L} 	imes \frac{1.00}{2.00} 	imes \frac{150}{300} = 0.625\,	ext{L}$$

Question 3

Which of the following best describes the molecular geometry of methane ($$\mathrm{CH_4$}) $$according to VSEPR theory?

Accepted Answer

Tetrahedral

Question 4

Which of the following is the correct balanced equation for the combustion of ethanol ($$\mathrm{C_2H_5OH}) in $$oxygen?

Accepted Answer

$$\mathrm{C_2H_5OH} + 3\,\mathrm{O_2$} \rightarrow 2\,\mathrm{CO_2$} + 3\,\mathrm{H_2O}$$

Question 5

A solution is prepared by dissolving 5.85 g of NaCl in enough water to make 500 mL of solution. What is the molarity of the solution? ($$\mathrm{NaCl}$$ molar mass = 58.5 g/mol)

Accepted Answer

$$M = \frac{	ext{moles}}{	ext{liters}} = \frac{5.85/58.5}{0.500} = 0.2\,\mathrm{mol/L}$$

Question 6

Which of the following statements about acids and bases is correct according to the Brønsted-Lowry theory?

Accepted Answer

An acid is a substance that donates a proton ($$\mathrm{H^+}$$), and a base is a substance that accepts a proton.

Question 7

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Ice is less dense than liquid water due to the hydrogen bonding arrangement in its solid state.

Question 8

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

The azimuthal (angular momentum) quantum number $$l$$

Question 9

A reaction has an equilibrium constant $$K_c = 1.0 	imes 10$$^{-5}$$ at 25°C. Which statement is true about the reaction at equilibrium?

Accepted Answer

The concentration of products is much less than the concentration of reactants.

Question 10

Which of the following is a correct application of the law of conservation of mass in a chemical reaction?

Accepted Answer

The total mass of reactants equals the total mass of products.

Question 11

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

Accepted Answer

$$\mathrm{$$NaNO_3$$}$$

Question 12

Which of the following best describes the energy change when a chemical bond is formed?

Accepted Answer

Energy is released when a bond is formed.

Question 13

A patient receives 500 mL of a 0.9% (w/v) NaCl solution intravenously. How many grams of NaCl did the patient receive?

Accepted Answer

$$0.9\,\mathrm{g}/100\,\mathrm{mL} 	imes 500\,\mathrm{mL} = 4.5\,\mathrm{g}$$

Question 14

Which of the following is a correct Lewis structure for carbon dioxide ($$\mathrm{CO_2$}$$)?

Accepted Answer

O=C=O, with each oxygen atom having two lone pairs

Question 15

Which of the following best describes the process of dissolving table salt ($$\mathrm{NaCl}) in $$water?

Accepted Answer

The $$\mathrm{Na^+}$$ and $$\mathrm{Cl^-}$$ ions are surrounded by water molecules due to ion-dipole interactions.

Question 16

Which of the following is the correct electron configuration for a neutral phosphorus atom ($$Z=15$$)?

Accepted Answer

$$1s^2$$\,$$2s^2$$\,$$2p^6$$\,$$3s^2$$\,$$3p^3$$

Question 17

A chemical reaction has an enthalpy change $$\Delta H = -250\,\mathrm{kJ}. $$Which statement is correct?

Accepted Answer

The reaction is exothermic and releases 250 kJ of energy.

Question 18

Which of the following best describes the difference between a covalent bond and an ionic bond?

Accepted Answer

A covalent bond involves the sharing of electrons, while an ionic bond involves the transfer of electrons.

Question 19

Which of the following is a correct statement about the effect of temperature on the equilibrium constant $$K$$ for an exothermic reaction?

Accepted Answer

Increasing temperature decreases $$K$$ for an exothermic reaction.

Syllabus Overview: General Chemistry

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