Q: Which formula is used to calculate the molarity ($$M) of a $$solution?

$$M = \frac{\text{moles of solute}}{\text{volume of solution in liters}}$$

Q: Which calculation would you use to determine the number of moles in $$25.0 g of $$glucose ($$C_6H_{12}O_6$, M = 180.16$ g/mol)?

$$\text{moles} = \frac{25.0}{180.16}$$

Question 1

Which of the following best describes Avogadro's number and its significance in chemistry?

Accepted Answer

It is the number of representative particles in one mole, allowing conversion between atomic/molecular scale and macroscopic quantities.

Question 2

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

Accepted Answer

$$0.50$$ mol

Question 3

Which statement correctly applies the law of multiple proportions?

Accepted Answer

Elements combine in fixed mass ratios to form compounds, and different compounds of the same elements have mass ratios that are simple whole numbers.

Question 4

A solution is prepared by dissolving $$5.00 g of $$NaCl in enough water to make $$250 mL of $$solution. What is the molarity of the solution? ($$M_{NaCl} = 58.44 g/$$mol)

Accepted Answer

$$0.342 M$$

Question 5

Which of the following is a correct application of Beer’s Law in spectrophotometry?

Accepted Answer

The absorbance of a solution is directly proportional to both the concentration of the solute and the path length of the light through the solution.

Question 6

A student prepares a $$1.00 L $$solution by diluting $$100 mL of$$ $$2.00 M $$HCl with water. What is the final concentration of HCl?

Accepted Answer

$$0.20 M$$

Question 7

Which of the following best describes a saturated solution?

Accepted Answer

A solution in which no more solute can dissolve at a given temperature.

Question 8

Which formula is used to calculate the molarity ($$M) of a $$solution?

Accepted Answer

$$M = \frac{	ext{moles of solute}}{	ext{volume of solution in liters}}$$

Question 9

A chemist needs to prepare $$500 mL of$$ $$0.250 M $$NaOH solution. How many grams of NaOH ($$M_{NaOH} = 40.00 g/$$mol) are required?

Accepted Answer

$$5.00 g$$

Question 10

Which of the following is NOT a representative particle as defined in the study materials?

Accepted Answer

Electron in a neutral atom

Question 11

A solution of CuSO$$_4$$ appears blue because:

Accepted Answer

It absorbs orange light and transmits blue light.

Question 12

Which calculation would you use to determine the number of moles in $$25.0 g of $$glucose ($$C_6H_{12}O_6$, M = 180.16$ g/mol)?

Accepted Answer

$$	ext{moles} = \frac{25.0}{180.16}$$

Question 13

Which of the following best describes the difference between an electrolyte and a nonelectrolyte solution?

Accepted Answer

Electrolyte solutions conduct electricity due to the presence of ions, while nonelectrolyte solutions do not conduct electricity.

Question 14

A student uses spectrophotometry to determine the concentration of a colored solution. If the absorbance is $$0.600$$, the path length is $$1.00 cm$$, and the molar absorptivity is $$200 L $$mol$$^{-1} cm$^{-1}$$, what is the concentration of the solution?

Accepted Answer

$$0.00300$$ mol/L

Question 15

Which of the following is a correct statement about the atomic view of chemical compounds?

Accepted Answer

Compounds are formed when atoms of different elements combine in fixed ratios.

Question 16

If $$0.250$$ mol of KBr is dissolved in $$500 mL of $$water, what is the molarity of the solution?

Accepted Answer

$$0.500 M$$

Question 17

Which of the following best explains why temperature affects the solubility of most solids in water?

Accepted Answer

Increasing temperature generally increases the kinetic energy of particles, allowing more solute to dissolve.

Question 18

A solution is prepared by mixing $$50.0 mL of$$ $$1.00 M $$NaCl with $$150.0 mL of $$water. What is the final concentration of NaCl?

Accepted Answer

$$0.250 M$$

Question 19

Which of the following is the correct formula for calculating the pH of an aqueous solution?

Accepted Answer

$$	ext{pH} = -\log[H^+]$$

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