Q: What is the formula weight (FW) of H2SO4, given the atomic weights: H = 1.0 amu, S = 32.1 amu, O = 16.0 amu?

$$2 \times 1.0 + 32.1 + 4 \times 16.0 = 98.1$$ amu

Q: Which equation correctly expresses the percent mass composition of an element in a compound?

$$\frac{\text{number of atoms of element} \times \text{atomic weight of element}}{\text{formula weight of substance}} \times 100\%$$

Q: Calculate the percent by mass of carbon in C12H22O11. (FW = 342.0 amu, C = 12.0 amu)

$$\frac{12 \times 12.0}{342.0} \times 100\% = 42.1\%$$

Q: How many molecules are in 1 mole of H2O?

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

Q: Which conversion factor would you use to convert from number of particles to number of moles?

$$\frac{1 \text{ mol}}{6.022 \times 10$$^{23}$$ \text{ particles}}$$

Q: A tablet contains 502 mg of CaCO3. What is the number of moles of CaCO3 in the tablet? (Molar mass = 100.086 g/mol)

$$\frac{502 \text{ mg}}{1000 \text{ mg/g}} \times \frac{1 \text{ mol}}{100.086 \text{ g}} = 0.00502$$ mol

Q: A blood glucose level of 126 mg/dL is considered a cause for concern. Convert this value to g/dL.

$$\frac{126 \text{ mg}}{1000} = 0.126 g/dL$$

Q: If you have 0.00502 mol of CaCO3, how many formula units are present? (Avogadro's number = $$6.022 \times 10$$^{23}$$)

$$0.00502 \times 6.022 \times 10$$^{23}$$ = 3.02 \times 10$$^{21}$$ formula units

Question 1

What is the formula weight (FW) of H2SO4, given the atomic weights: H = 1.0 amu, S = 32.1 amu, O = 16.0 amu?

Accepted Answer

$$2 	imes 1.0 + 32.1 + 4 	imes 16.0 = 98.1$$ amu

Question 2

Which equation correctly expresses the percent mass composition of an element in a compound?

Accepted Answer

$$\frac{	ext{number of atoms of element} 	imes 	ext{atomic weight of element}}{	ext{formula weight of substance}} 	imes 100\%$$

Question 3

Calculate the percent by mass of carbon in C12H22O11. (FW = 342.0 amu, C = 12.0 amu)

Accepted Answer

$$\frac{12 	imes 12.0}{342.0} 	imes 100\% = 42.1\%$$

Question 4

How many molecules are in 1 mole of H2O?

Accepted Answer

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

Question 5

A sample contains 5.380 g of glucose (C6H12O6). What is the number of moles present? (Molar mass = 180.0 g/mol)

Accepted Answer

$$\frac{5.380}{180.0} = 0.02989$$ mol

Question 6

Which conversion factor would you use to convert from number of particles to number of moles?

Accepted Answer

$$\frac{1 	ext{ mol}}{6.022 	imes 10$$^{23}$$ 	ext{ particles}}$$

Question 7

A tablet contains 502 mg of CaCO3. What is the number of moles of CaCO3 in the tablet? (Molar mass = 100.086 g/mol)

Accepted Answer

$$\frac{502 	ext{ mg}}{1000 	ext{ mg/g}} 	imes \frac{1 	ext{ mol}}{100.086 	ext{ g}} = 0.00502$$ mol

Question 8

Which of the following is NOT a basic type of chemical reaction?

Accepted Answer

Electrolysis

Question 9

Balance the following equation: $$\_\,	ext{C}_3	ext{H}_8(g) + \_\,	ext{O}_2(g) ightarrow \_\,	ext{CO}_2(g) + \_\,	ext{H}_2	ext{O}(g). $$What is the coefficient of $$	ext{O}_2$$?

Accepted Answer

5

Question 10

A blood glucose level of 126 mg/dL is considered a cause for concern. Convert this value to g/dL.

Accepted Answer

$$\frac{126 	ext{ mg}}{1000} = 0.126 g/dL$$

Question 11

If you have 0.00502 mol of CaCO3, how many formula units are present? (Avogadro's number = $$6.022 	imes 10$$^{23}$$)

Accepted Answer

$$0.00502 	imes 6.022 	imes 10$$^{23}$$ = 3.02 	imes 10$$^{21}$$ formula units

Question 12

Which statement best describes the relationship between atomic mass units (amu) and grams for a mole of a substance?

Accepted Answer

The atomic weight in amu is numerically equal to the mass in grams of 1 mole of the element.

Question 13

Which of the following is the correct balanced equation for the reaction of SO2 with O2 to produce SO3?

Accepted Answer

$$2\,	ext{SO}_2(g) + 	ext{O}_2(g) ightarrow 2\,	ext{SO}_3(g)$$

Question 14

Which physical state symbol is used to indicate a substance dissolved in water?

Accepted Answer

(aq)

Question 15

A chemical equation is balanced when:

Accepted Answer

The number of atoms of each element is equal on both sides of the equation.

Question 16

Which step should you take first when balancing a chemical equation?

Accepted Answer

Balance the element that appears in the fewest chemical formulas.

Question 17

Which of the following is a real-world example of a combustion reaction?

Accepted Answer

Burning methane in a Bunsen burner to produce CO2 and H2O.

Question 18

If a chemical reaction produces 10.0 g of product but the theoretical yield is 12.0 g, what is the percent yield?

Accepted Answer

$$\frac{10.0}{12.0} 	imes 100\% = 83.3\%$$

Chemical Quantities, Moles, and Chemical Reactions: Core Concepts and Calculations

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