Q: Calculate the molarity of a solution prepared by dissolving 23.7 g NaOH (MW = 40.00 g/mol) in enough water to make 2.50 L of solution.

$$\frac{23.7\ \text{g}}{40.00\ \text{g/mol}} = 0.5925\ \text{mol}$$, $$M = \frac{0.5925\ \text{mol}}{2.50\ \text{L}} = 0.237\ \text{M}$$

Q: A student dilutes 100 mL of 5.0 M KCl to a final volume of 925 mL. What is the resulting molarity?

$$M_1V_1 = M_2V_2 \rightarrow 5.0\ \text{M} \times 100\ \text{mL} = M_2$ \times 925\ \text{mL} \rightarrow M_2$ = 0.54\ \text{M}$$

Q: Which of the following is a precipitation reaction?

$$\text{ZnBr}_2 (aq) + 2\ \text{KOH} (aq) \rightarrow \text{Zn(OH)}_2 (s) + 2\ \text{KBr} (aq)$$

Q: A solution is prepared by dissolving 2.81 g of an unknown compound in water to yield 150 mL of solution. The concentration is 0.075 M. What is the molecular weight of the substance?

$$\text{Molecular weight} = \frac{2.81\ \text{g}}{0.075\ \text{mol/L} \times 0.150\ \text{L}} = 250\ \text{g/mol}$$

Question 1

Which of the following best describes a solution in chemistry?

Accepted Answer

A homogeneous mixture of two or more substances with uniform composition.

Question 2

Given the images of three beakers, each containing a different mixture, which one most likely represents a colloid?

Accepted Answer

A beaker with a cloudy appearance but no visible settling of particles.

Question 3

Calculate the molarity of a solution prepared by dissolving 23.7 g NaOH (MW = 40.00 g/mol) in enough water to make 2.50 L of solution.

Accepted Answer

$$\frac{23.7\ 	ext{g}}{40.00\ 	ext{g/mol}} = 0.5925\ 	ext{mol}$$, $$M = \frac{0.5925\ 	ext{mol}}{2.50\ 	ext{L}} = 0.237\ 	ext{M}$$

Question 4

Which of the following solutions will have the highest concentration of bromide ions?

Accepted Answer

0.10 M AlBr$$_3$$

Question 5

A student dilutes 100 mL of 5.0 M KCl to a final volume of 925 mL. What is the resulting molarity?

Accepted Answer

$$M_1V_1 = M_2V_2 ightarrow 5.0\ 	ext{M} 	imes 100\ 	ext{mL} = M_2$ 	imes 925\ 	ext{mL} ightarrow M_2$ = 0.54\ 	ext{M}$$

Question 6

According to the solubility rules, which of the following ionic compounds will be insoluble in water?

Accepted Answer

BaSO$$_4$$

Question 7

Which of the following represents a strong electrolyte?

Accepted Answer

NaOH

Question 8

Which of the following is a non-electrolyte?

Accepted Answer

C$$_2H$_5OH$

Question 9

Which of the following is a precipitation reaction?

Accepted Answer

$$	ext{ZnBr}_2 (aq) + 2\ 	ext{KOH} (aq) ightarrow 	ext{Zn(OH)}_2 (s) + 2\ 	ext{KBr} (aq)$$

Question 10

Which of the following compounds contains oxygen with the lowest oxidation state?

Accepted Answer

$$	ext{O}_2$$

Question 11

Which element is being reduced in the following reaction? $$	ext{Cr}_2	ext{O}_7$$^{2-}$$ + 3\ 	ext{HNO}_2 + 5\ 	ext{H}^+ ightarrow 2\ 	ext{Cr}^{3+} + 3\ 	ext{NO}_3^- + 4\ 	ext{H}_2	ext{O}$$

Accepted Answer

Chromium (Cr)

Question 12

Which of the following reactions is a redox reaction?

Accepted Answer

Ba (s) + Cl$$_2 (g$$) $$\rightarrow$$ BaCl$$_2 (aq)$$

Question 13

Balance the following redox reaction in acidic solution: $$	ext{NO}_2^- (aq) + 	ext{Cr}_2	ext{O}_7$$^{2-}$$ (aq) ightarrow 	ext{Cr}^{3+} (aq) + 	ext{NO}_3^- (aq). $$What is the coefficient of $$	ext{Cr}^{3+}$$?

Accepted Answer

2

Question 14

Based on the activity series, will a reaction occur if Zn (s) is added to NiCl$$_2 (aq$$)? If so, what are the products?

Accepted Answer

Yes, ZnCl$$_2 (aq) $$and Ni (s)

Question 15

Which of the following best describes the role of an oxidizing agent in a redox reaction?

Accepted Answer

It gains electrons and is reduced.

Question 16

A solution is prepared by dissolving 2.81 g of an unknown compound in water to yield 150 mL of solution. The concentration is 0.075 M. What is the molecular weight of the substance?

Accepted Answer

$$	ext{Molecular weight} = \frac{2.81\ 	ext{g}}{0.075\ 	ext{mol/L} 	imes 0.150\ 	ext{L}} = 250\ 	ext{g/mol}$$

Question 17

Which of the following pairs of compounds are both insoluble in water?

Accepted Answer

PbSO$$_4$$ and Pb$$_3(PO$_4$$)$$_2$$

Question 18

Which of the following statements is true regarding electrolytes?

Accepted Answer

Strong electrolytes completely dissociate into ions in solution.

Study Guide: Reactions in Aqueous Solution (General Chemistry)

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