Q: A student mixes 100.0 mL of 0.200 M NaCl with 200.0 mL of 0.100 M NaCl. What is the final concentration of NaCl in the mixture?

$$C_f = \frac{(0.200 \times 100.0) + (0.100 \times 200.0)}{100.0 + 200.0} = \frac{20.0 + 20.0}{300.0} = 0.133\ \mathrm{M}$$

Q: A sample of 50.0 g of Al (specific heat $$c = 0.900\ \mathrm{J/g\cdot ^\circ C}) is $$heated from 25 $$^\circC to 75$$ $$^\circC. $$How much heat is absorbed?

$$q = mc\Delta T = 50.0 \times 0.900 \times (75-25) = 2250\ \mathrm{J}$$

Question 1

Trinitrotoluene (TNT) is a chemical explosive. What is the coefficient for H$$_2O $$when the equation below is balanced?

$$2\mathrm{C}_7\mathrm{H}_5\mathrm{N}_3\mathrm{O}_6 + 21\mathrm{O}_2 \rightarrow 14\mathrm{CO}_2 + 5\mathrm{H}_2\mathrm{O} + 6\mathrm{N}_2$$

Accepted Answer

5

Question 2

In the balanced chemical reaction below, what is the coefficient for O$$_2$$?

$$\mathrm{CH}_4 + \underline{\phantom{0}}\mathrm{O}_2 \rightarrow \mathrm{CO}_2 + 2\mathrm{H}_2\mathrm{O}$$

Accepted Answer

2

Question 3

Which of the following represents a mixture of H$$_2$$ and O$$_2$$ gases, not a chemical reaction product?

Accepted Answer

A diagram showing separate H$$_2$$ and O$$_2$$ molecules

Question 4

A reaction takes place in a flexible container initially at 228 kPa and a volume of 3.00 liters. A reaction was placed causing the container to increase in volume to 2.50 liters and the temperature remains 273 K. What is the final pressure, in kPa, if the system is ideal?

Accepted Answer

$$P_1V_1 = P_2V_2 \implies P_2$ = \frac{P_1V_1}{V_2$} = \frac{228 	imes 3.00}{2.50} = 273.6\ \mathrm{kPa}$$

Question 5

Which of the following reactions is a redox reaction?

A. $$\mathrm{NaOH} + \mathrm{HCl} \rightarrow \mathrm{NaCl} + \mathrm{H}_2\mathrm{O}
B$$. $$2\mathrm{Na} + 2\mathrm{H}_2\mathrm{O} \rightarrow 2\mathrm{NaOH} + \mathrm{H}_2
C$$. $$\mathrm{AgNO}_3 + \mathrm{NaCl} \rightarrow \mathrm{AgCl} + \mathrm{NaNO}_3
D$$. $$\mathrm{CaCO}_3 \rightarrow \mathrm{CaO} + \mathrm{CO}_2$$

Accepted Answer

B

Question 6

A student mixes 100.0 mL of 0.200 M NaCl with 200.0 mL of 0.100 M NaCl. What is the final concentration of NaCl in the mixture?

Accepted Answer

$$C_f = \frac{(0.200 	imes 100.0) + (0.100 	imes 200.0)}{100.0 + 200.0} = \frac{20.0 + 20.0}{300.0} = 0.133\ \mathrm{M}$$

Question 7

Which of the following best describes the sign of $$\Delta H$$ for the reaction $$\mathrm{H}_2\mathrm{O}(l) \rightarrow \mathrm{H}_2\mathrm{O}(g)$$?

Accepted Answer

Positive, the process is endothermic

Question 8

Which of the following substances will result in a precipitate when mixed with AgNO$$_3 (aq$$)?

Accepted Answer

NaCl(aq)

Question 9

A solution contains 0.50 mol of NaCl in 250 mL of water. What is the molarity of the solution?

Accepted Answer

$$M = \frac{0.50\ \mathrm{mol}}{0.250\ \mathrm{L}} = 2.0\ \mathrm{M}$$

Question 10

Which of the following ions is always soluble in water according to the solubility rules?

Accepted Answer

NH$$_4^+$$

Question 11

Which of the following reactions will result in the formation of a gas?

A. $$\mathrm{Na}_2\mathrm{CO}_3(aq) + 2\mathrm{HCl}(aq) \rightarrow 2\mathrm{NaCl}(aq) + \mathrm{H}_2\mathrm{O}(l) + \mathrm{CO}_2(g)
B$$. $$\mathrm{NaCl}(aq) + \mathrm{AgNO}_3(aq) \rightarrow \mathrm{AgCl}(s) + \mathrm{NaNO}_3(aq)
C$$. $$\mathrm{NaOH}(aq) + \mathrm{HCl}(aq) \rightarrow \mathrm{NaCl}(aq) + \mathrm{H}_2\mathrm{O}(l)
D$$. $$\mathrm{BaCl}_2(aq) + \mathrm{Na}_2\mathrm{SO}_4(aq) \rightarrow \mathrm{BaSO}_4(s) + 2\mathrm{NaCl}(aq)$$

Accepted Answer

A

Question 12

Which of the following best describes the energy change when water freezes?

$$\mathrm{H}_2\mathrm{O}(l) \rightarrow \mathrm{H}_2\mathrm{O}(s)$$

Accepted Answer

The process is exothermic; heat is released to the surroundings

Question 13

Which of the following compounds contains nitrogen in its highest oxidation state?

A. NO
B. NO$$_2
C. N$_2
D. NO$_3^-$$

Accepted Answer

D

Question 14

Which of the following is a weak acid?

A. HCl
B. HNO$$_3
C. CH$_3$$COOH
D. H$$_2SO$_4$$

Accepted Answer

C

Question 15

A sample of 50.0 g of Al (specific heat $$c = 0.900\ \mathrm{J/g\cdot ^\circ C}) is $$heated from 25 $$^\circC to 75$$ $$^\circC. $$How much heat is absorbed?

Accepted Answer

$$q = mc\Delta T = 50.0 	imes 0.900 	imes (75-25) = 2250\ \mathrm{J}$$

Question 16

Which of the following best describes the role of water in the reaction below?

$$\mathrm{NaOH}(aq) + \mathrm{HCl}(aq) \rightarrow \mathrm{NaCl}(aq) + \mathrm{H}_2\mathrm{O}(l)$$

Accepted Answer

Water is a product formed by the neutralization of an acid and a base

Question 17

Which of the following best explains why NaCl dissolves in water but AgCl does not?

Accepted Answer

NaCl is soluble due to strong ion-dipole interactions with water, while AgCl is insoluble due to its low solubility product

Question 18

Which of the following reactions is a precipitation reaction?

A. $$\mathrm{Na}_2\mathrm{SO}_4(aq) + \mathrm{BaCl}_2(aq) \rightarrow \mathrm{BaSO}_4(s) + 2\mathrm{NaCl}(aq)
B$$. $$\mathrm{NaOH}(aq) + \mathrm{HCl}(aq) \rightarrow \mathrm{NaCl}(aq) + \mathrm{H}_2\mathrm{O}(l)
C$$. $$\mathrm{Na}_2\mathrm{CO}_3(aq) + 2\mathrm{HCl}(aq) \rightarrow 2\mathrm{NaCl}(aq) + \mathrm{H}_2\mathrm{O}(l) + \mathrm{CO}_2(g)
D$$. $$\mathrm{AgNO}_3(aq) + \mathrm{NaNO}_3(aq) \rightarrow \mathrm{AgNO}_3(aq) + \mathrm{NaNO}_3(aq)$$

Accepted Answer

A

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