Q: A 0.250 mol sample of NaCl is dissolved in enough water to make 500.0 mL of solution. What is the molarity of the solution?

$$M = \frac{0.250\ \text{mol}}{0.5000\ \text{L}} = 0.500\ \text{M}$$

Q: A reaction has $$\Delta H = -125\ \text{kJ}$$ and $$\Delta S = -200\ \text{J/K}. At $$what temperature (in K) does the reaction become non-spontaneous? ($$\Delta G = \Delta H - T\Delta S)$$

$$T = \frac{\Delta H}{\Delta S} = \frac{-125,000\ \text{J}}{-200\ \text{J/K}} = 625\ \text{K}$$

Q: A sample of copper has a mass of 63.5 g. How many atoms of copper are present in the sample? (Molar mass of Cu = 63.5 g/mol, $$N_A = 6.022 \times 10$$^{23}$$ mol$$^{-1}$$)

$$6.02 \times 10$$^{23}$$ atoms

Question 1

A sample of gas occupies 2.50 L at 300 K and 1.00 atm. If the temperature is increased to 400 K and the pressure is increased to 2.00 atm, what will be the new volume of the gas? (Assume ideal gas behavior.)

Accepted Answer

$$V_2$$ = \frac{$$P_1$$ $$V_1$$ $$T_2$$}{$$T_1$$ $$P_2$$} = \frac{(1.00\ 	ext{atm})(2.50\ 	ext{L})(400\ 	ext{K})}{(300\ 	ext{K})(2.00\ 	ext{atm})} = 1.67\ 	ext{L}$$

Question 2

Which of the following statements best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the composition is not uniform throughout.

Question 3

A student measures the mass of a sample as 12.30 g, 12.28 g, and 12.31 g in three trials. The true mass is 12.00 g. Which statement best describes the accuracy and precision of the measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 4

Which of the following is the correct electron configuration for a neutral atom of nickel (Ni, atomic number 28)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^6$$\ $$4s^2$$\ $$3d^8$$

Question 5

A 0.250 mol sample of NaCl is dissolved in enough water to make 500.0 mL of solution. What is the molarity of the solution?

Accepted Answer

$$M = \frac{0.250\ 	ext{mol}}{0.5000\ 	ext{L}} = 0.500\ 	ext{M}$$

Question 6

Which of the following elements is most likely to form a +2 cation in binary ionic compounds?

Accepted Answer

Calcium

Question 7

A reaction has $$\Delta H = -125\ 	ext{kJ}$$ and $$\Delta S = -200\ 	ext{J/K}. At $$what temperature (in K) does the reaction become non-spontaneous? ($$\Delta G = \Delta H - T\Delta S)$$

Accepted Answer

$$T = \frac{\Delta H}{\Delta S} = \frac{-125,000\ 	ext{J}}{-200\ 	ext{J/K}} = 625\ 	ext{K}$$

Question 8

Which of the following best describes the process of ionization energy?

Accepted Answer

The energy required to remove an electron from a gaseous atom.

Question 9

A sample of copper has a mass of 63.5 g. How many atoms of copper are present in the sample? (Molar mass of Cu = 63.5 g/mol, $$N_A = 6.022 	imes 10$$^{23}$$ mol$$^{-1}$$)

Accepted Answer

$$6.02 	imes 10$$^{23}$$ atoms

Question 10

Which of the following is the correct empirical formula for a compound that is 40.0% C, 6.7% H, and 53.3% O by mass?

Accepted Answer

$$CH_2O$$

Question 11

A 1.00 L container holds 0.10 mol of O$$_2$$ gas at 300 K. What is the pressure in the container? ($$R = 0.0821 L$$·atm·mol$$^{-1}$$·K$$^{-1})$$

Accepted Answer

$$P = 2.46\ 	ext{atm}$$

Question 12

Which of the following best explains why water has a higher boiling point than methane?

Accepted Answer

Water forms hydrogen bonds, which are stronger than the London dispersion forces in methane.

Question 13

Which of the following is the correct balanced equation for the combustion of propane ($$C_3H_8$$)?

Accepted Answer

$$C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$$

Question 14

A solution is prepared by dissolving 10.0 g of NaOH in enough water to make 250.0 mL of solution. What is the molarity of the solution? (Molar mass of NaOH = 40.0 g/mol)

Accepted Answer

$$M = \frac{10.0\ 	ext{g}}{40.0\ 	ext{g/mol}} \div 0.250\ 	ext{L} = 1.00\ 	ext{M}$$

Question 15

Which of the following is the correct name for $$Fe_2O_3$$?

Accepted Answer

Iron(III) oxide

Question 16

A sample of $$C_2H_6$$ contains $$3.01 	imes 10$$^{23}$$ molecules. How many moles of C_2H_6$ are present?

Accepted Answer

$$0.500$$ mol

Question 17

Which of the following is a correct statement about the periodic table?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 18

Which of the following is the correct formula for the compound formed between aluminum and oxygen?

Accepted Answer

$$Al_2O_3$$

Question 19

A reaction mixture contains 0.50 mol of $$A$$ and 0.50 mol of $$B in a 1.0 L $$container. If the equilibrium constant $$K_c$$ for the reaction $$A + B \rightleftharpoons C is 2.0$$, what is the equilibrium concentration of $$C$$?

Accepted Answer

$$[C] = 0.33\ 	ext{mol/L}$$

Question 20

Which of the following best describes the effect of increasing temperature on the rate constant $$k of a $$chemical reaction, according to the Arrhenius equation?

Accepted Answer

The rate constant $$k$$ increases exponentially with temperature.

General Chemistry I: Key Concepts, Formulas, and Practice Questions

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