Q: What is the molar mass of Ca(NO$$_3$$)$$_2$$? (Atomic masses: Ca = 40.08 g/mol, N = 14.01 g/mol, O = 16.00 g/mol)

$$40.08 + 2 \times (14.01 + 3 \times 16.00) = 164.10 g/$$mol

Q: How many oxygen atoms are present in 0.350 mol of CO$$_2$$?

$$0.350 \text{ mol} \times 6.02 \times 10$$^{23}$$ \text{ molecules/mol} \times 2 = 4.21 \times 10$$^{23}$$ oxygen atoms

Q: Calculate the number of oxygen atoms in 2.00 g of H$$_2CO$_3. ($$Molar mass H$$_2CO$_3 = 62.03 g/$$mol)

$$2.00 \text{ g} \div 62.03 \text{ g/mol} \times 6.02 \times 10$$^{23}$$ \text{ molecules/mol} \times 3 = 5.83 \times 10$$^{22}$$ oxygen atoms

Q: What is the mass percent of oxygen in acetic acid (C$$_2H$_4O$_2$$)? (Molar mass C$$_2H$_4O$_2 = 60 g/$$mol, mass of O in 1 mol = 32 g)

$$\frac{32}{60} \times 100\% = 53.33\%$$

Q: If the recommended daily allowance of iodine is 150 μg, how much KI (potassium iodide) should you eat to meet this requirement? (Mass % I in KI = 76.45%)

$$\frac{150}{0.7645} = 196 \text{ μg} KI$$

Question 1

What is the molar mass of Ca(NO$$_3$$)$$_2$$? (Atomic masses: Ca = 40.08 g/mol, N = 14.01 g/mol, O = 16.00 g/mol)

Accepted Answer

$$40.08 + 2 	imes (14.01 + 3 	imes 16.00) = 164.10 g/$$mol

Question 2

How many oxygen atoms are present in 0.350 mol of CO$$_2$$?

Accepted Answer

$$0.350 	ext{ mol} 	imes 6.02 	imes 10$$^{23}$$ 	ext{ molecules/mol} 	imes 2 = 4.21 	imes 10$$^{23}$$ oxygen atoms

Question 3

Calculate the number of oxygen atoms in 2.00 g of H$$_2CO$_3. ($$Molar mass H$$_2CO$_3 = 62.03 g/$$mol)

Accepted Answer

$$2.00 	ext{ g} \div 62.03 	ext{ g/mol} 	imes 6.02 	imes 10$$^{23}$$ 	ext{ molecules/mol} 	imes 3 = 5.83 	imes 10$$^{22}$$ oxygen atoms

Question 4

What is the mass percent of oxygen in acetic acid (C$$_2H$_4O$_2$$)? (Molar mass C$$_2H$_4O$_2 = 60 g/$$mol, mass of O in 1 mol = 32 g)

Accepted Answer

$$\frac{32}{60} 	imes 100\% = 53.33\%$$

Question 5

If the recommended daily allowance of iodine is 150 μg, how much KI (potassium iodide) should you eat to meet this requirement? (Mass % I in KI = 76.45%)

Accepted Answer

$$\frac{150}{0.7645} = 196 	ext{ μg} KI$$

Question 6

A compound is decomposed to produce 165 g C, 27.8 g H, and 220.2 g O. What is the empirical formula? (Atomic masses: C = 12.01, H = 1.008, O = 16.00)

Accepted Answer

C$$_6H$_12O$_8$$

Question 7

Ibuprofen has a mass percent composition of C 75.69%, H 8.80%, O 15.51%. What is its empirical formula?

Accepted Answer

C$$_{13}H$_{18}O$_2$$

Question 8

A compound has a molecular weight of 58 g/mol and is composed of 82.76% C and the remainder H. What is its molecular formula?

Accepted Answer

C$$_4H$_{10}$$

Question 9

Which of the following is the correct name for FeCl$$_2$$?

Accepted Answer

Iron(II) chloride

Question 10

What is the correct formula for sodium nitrate?

Accepted Answer

NaNO$$_3$$

Question 11

Which of the following is the correct name for Cu$$_2O$$?

Accepted Answer

Copper(I) oxide

Question 12

What is the charge on the phosphate ion (PO$$_4$$)?

Accepted Answer

-3

Question 13

Which of the following is the correct name for N$$_2O$_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 14

What is the correct formula for ammonium sulfate?

Accepted Answer

(NH$$_4$$)$$_2SO$_4$$

Question 15

Which of the following is the correct name for HNO$$_3$$?

Accepted Answer

Nitric acid

Question 16

What is the empirical formula for a compound containing 40.0% C, 6.7% H, and 53.3% O?

Accepted Answer

CH$$_2O$$

Question 17

Which of the following is the correct name for K$$_2SO$_4$$?

Accepted Answer

Potassium sulfate

Question 18

What is the correct formula for calcium phosphate?

Accepted Answer

Ca$$_3(PO$_4$$)$$_2$$

Question 19

Which of the following is the correct name for SO$$_2$$?

Accepted Answer

Sulfur dioxide

Question 20

What is the correct formula for hydrobromic acid?

Accepted Answer

HBr

Molar Mass, Empirical Formulas, and Nomenclature of Compounds

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