Q: A can contains $$16.2 g of $$aluminum. How many aluminum atoms are in the can? (Molar mass of Al = $$26.98 g/$$mol, Avogadro's number = $$6.022 \times 10$$^{23}$$ atoms/mol)

$$3.61 \times 10$$^{23}$$ atoms

Q: A $$48.3 g $$sample of zinc contains how many atoms? (Molar mass of Zn = $$65.39 g/$$mol, Avogadro's number = $$6.022 \times 10$$^{23}$$ atoms/mol)

$$4.45 \times 10$$^{23}$$ atoms

Question 1

A silver ring contains $$1.1 	imes 10$$^{22}$$ silver atoms. How many moles of silver are in the ring? (Avogadro's number: 6.022$$ 	imes $$10^{23}$$ atoms/mol)

Accepted Answer

$$1.8 	imes 10$$^{-2}$$ mol

Question 2

How many atoms are present in $$4.8$$ mol of copper? (Avogadro's number: $$6.022 	imes 10$$^{23}$$ atoms/mol)

Accepted Answer

$$2.9 	imes 10$$^{24}$$ atoms

Question 3

A can contains $$16.2 g of $$aluminum. How many aluminum atoms are in the can? (Molar mass of Al = $$26.98 g/$$mol, Avogadro's number = $$6.022 	imes 10$$^{23}$$ atoms/mol)

Accepted Answer

$$3.61 	imes 10$$^{23}$$ atoms

Question 4

Calculate the mass (in grams) of $$1.75$$ mol of water ($$H_2O). ($$Molar mass of $$H_2O = 18.02 g/$$mol)

Accepted Answer

$$31.5 g$$

Question 5

How many moles of oxygen are in $$1.7$$ mol of $$CaCO_3$$?

Accepted Answer

$$5.1$$ mol

Question 6

A $$55.4 g $$sample of carvone ($$C_{10}H$$_{14}$$O) is $$analyzed. How many grams of carbon are present? (Molar mass of carvone = $$150.2 g/$$mol, atomic mass of C = $$12.01$ g/mol)

Accepted Answer

Question 7

A $$4.78 	imes 10$$^{24}$$ sample of NO_2$ molecules is analyzed. What is the mass of this sample? (Molar mass of NO_2$ = 46.01 g/$$mol, Avogadro's number = $$6.022 	imes 10$$^{23}$$ molecules/mol)

Accepted Answer

$$365 g$$

Question 8

A laboratory decomposes a compound containing nitrogen and oxygen, producing $$24.5 g of $$nitrogen and $$70.0 g of $$oxygen. What is the empirical formula of the compound? (Atomic masses: N = $$14.01 g/$$mol, O = $$16.00 g/$$mol)

Accepted Answer

$$N_2O_5$$

Question 9

A $$3.249 g $$sample of titanium reacts with oxygen to form $$5.40 g of $$titanium oxide. What is the empirical formula of the oxide? (Atomic masses: Ti = $$47.87 g/$$mol, O = $$16.00 g/$$mol)

Accepted Answer

$$TiO_2$$

Question 10

A compound has an empirical formula of $$C_5H_4$$ and a molar mass of $$128.16 g/$$mol. What is its molecular formula? (Empirical formula mass: $$64.09 g/$$mol)

Accepted Answer

$$C_{10}H_8$

Question 11

Calculate the mass percent of chlorine in freon-114 ($$C_2Cl_4F_2). ($$Atomic masses: C = $$12.01 g/$$mol, Cl = $$35.45 g/$$mol, F = $$19.00 g/$$mol)

Accepted Answer

$$60.56\%$$

Question 12

If a woman consumes $$22 g of $$sodium chloride, how much sodium does she consume? (Sodium chloride is $$39\%$$ sodium by mass)

Accepted Answer

$$8.6 g$$

Question 13

A $$48.3 g $$sample of zinc contains how many atoms? (Molar mass of Zn = $$65.39 g/$$mol, Avogadro's number = $$6.022 	imes 10$$^{23}$$ atoms/mol)

Accepted Answer

$$4.45 	imes 10$$^{23}$$ atoms

Question 14

What is the mass percent of potassium in potassium oxide ($$K_2O$$)? (Atomic masses: K = $$39.10 g/$$mol, O = $$16.00 g/$$mol)

Accepted Answer

$$83.0\%$$

Question 15

A $$6.73$$ mol sample of aluminum is weighed. What is its mass in grams? (Molar mass of Al = $$26.98 g/$$mol)

Accepted Answer

$$182 g$$

Question 16

A $$57.2 g $$sample of $$TiO_2$$ contains what mass of titanium? (Mass percent of Ti in $$TiO_2 is$$ $$59.9\%)$$

Accepted Answer

$$34.3 g$$

Question 17

A $$79.2 g $$sample of $$Fe_2O_3$$ contains how many grams of iron? (Molar mass of $$Fe_2O_3 = 159.70 g/$$mol, atomic mass of Fe = $$55.85 g/$$mol)

Accepted Answer

$$55.4 g$$

Question 18

A compound has the empirical formula $$CH$$ and a molar mass of $$26.04 g/$$mol. What is its molecular formula? (Empirical formula mass: $$13.02 g/$$mol)

Accepted Answer

$$C_2H_2$$

Question 19

A $$7.20$$ mol sample of $$H_2SO_4$$ contains how many moles of oxygen?

Accepted Answer

$$28.8$$ mol

Chapter 6: Chemical Composition – The Mole Concept and Chemical Formulas

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