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)

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

Study Guide - Practice Questions

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