Q: A cup of coffee contains 125 mg of caffeine ($$\mathrm{C_8H_{10}N_4O_2}$$, $$\mathrm{M_{caffeine}} = 194.19\ \mathrm{g\ $$mol^{-1}$$}). $$How many nitrogen atoms are present in the cup?

$$1.55 \times 10$$^{21}$$ atoms N

Question 1

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons between a metal and a nonmetal, resulting in oppositely charged ions attracted by electrostatic forces, while covalent bonds involve the sharing of electrons between two nonmetal atoms.

Question 2

Which of the following compounds is an example of a molecular compound?

Accepted Answer

CO

Question 3

What is the correct chemical formula for aluminum phosphate?

Accepted Answer

$$\mathrm{$$AlPO_4$$}$$

Question 4

A sample of calcium carbonate (CaCO$$_3) $$weighs 502 mg. How many moles of CaCO$$_3$$ are present in the sample? ($$\mathrm{M_{$$CaCO_3$$}} = 100.09\ \mathrm{g\ $$mol^{-1}$$})$$

Accepted Answer

$$5.02 	imes 10$$^{-3}$$ mol

Question 5

Which of the following is the correct name for the compound with the formula $$\mathrm{Cu(OH)_2}$$?

Accepted Answer

Copper (II) hydroxide

Question 6

What is the empirical formula of a compound that contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 7

A 12.501 g sample of a hydrocarbon produces 38.206 g of CO$$_2$$ and 18.752 g of H$$_2O $$upon combustion. What is the empirical formula of the hydrocarbon? ($$\mathrm{M_{CO_2$}} = 44.011\ \mathrm{g\ $$mol^{-1}$$}$$, $$\mathrm{M_{H_2O}} = 18.016\ \mathrm{g\ $$mol^{-1}$$})$$

Accepted Answer

$$\mathrm{CH_4$}$$

Question 8

Which of the following is the correct formula for chlorous acid?

Accepted Answer

$$\mathrm{$$HClO_2$$}$$

Question 9

What is the mass percent of oxygen in the compound CuSO$$_4\cdot5H$_2O$$? ($$\mathrm{M_{$$CuSO_4$$\cdot5H_2O}} = 249.68\ \mathrm{g\ $$mol^{-1}$$})$$

Accepted Answer

51.3%

Question 10

Which of the following is a polyatomic ion?

Accepted Answer

$$\mathrm{NO_3$^-}$$

Question 11

What is the correct name for the compound Rb$$_2S$$?

Accepted Answer

Rubidium sulfide

Question 12

A cup of coffee contains 125 mg of caffeine ($$\mathrm{C_8H_{10}N_4O_2}$$, $$\mathrm{M_{caffeine}} = 194.19\ \mathrm{g\ $$mol^{-1}$$}). $$How many nitrogen atoms are present in the cup?

Accepted Answer

$$1.55 	imes 10$$^{21}$$ atoms N

Question 13

Which of the following is the correct formula for diarsenic trisulfide?

Accepted Answer

$$\mathrm{As_2S_3}$$

Question 14

What is the molecular formula of a compound with an empirical formula of CH and a molar mass of 78 g/mol?

Accepted Answer

$$\mathrm{C_6H_6}$$

Question 15

Which of the following is the correct name for the acid with the formula $$\mathrm{HS(aq)}$$?

Accepted Answer

Hydrosulfuric acid

Question 16

Which of the following statements about empirical and molecular formulas is correct?

Accepted Answer

The molecular formula is always a multiple of the empirical formula.

Question 17

Which of the following is the correct formula for hydrofluoric acid?

Accepted Answer

$$\mathrm{HF}$$

Question 18

A compound contains 75.27% silver by mass. How many grams of silver chloride are required to plate 155 mg of pure silver?

Accepted Answer

0.206 g

Question 19

Which of the following is the correct name for the hydrate $$\mathrm{Mg(BrO)_2 \cdot 6H_2O}$$?

Accepted Answer

Magnesium bromate hexahydrate

Chapter 3: Molecules, Compounds, and Nomenclature – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard