Q: Convert $$0.0250\ \mathrm{kg} to $$milligrams ($$\mathrm{mg}).$$

$$2.50 \times 10^5$\ \mathrm{mg}$$

Q: A student needs to convert $$5.0\ \mathrm{cm} to $$meters using dimensional analysis. Which of the following is the correct setup?

$$5.0\ \mathrm{cm} \times \frac{1\ \mathrm{m}}{100\ \mathrm{cm}}$$

Q: How many molecules are present in $$0.250$$ moles of $$\mathrm{CO_2$}$$? ($$N_A = 6.022 \times 10$$^{23}$$\ \mathrm{mol}^{-1})$$

$$1.51 \times 10$$^{24}$$ molecules

Q: How many atoms are present in $$3.00$$ moles of $$\mathrm{Al}$$?

$$1.81 \times 10$$^{24}$$ atoms

Q: Which of the following is the correct calculation for mass percent of oxygen in $$\mathrm{H_2O}$$?

$$\frac{16.0}{18.0} \times 100\%$$

Question 1

A sample of ethanol has a mass of 45.6 g and a volume of 57.0 mL. What is the density of ethanol in $$\mathrm{g/cm^3$}$$? (Assume $$1\ \mathrm{mL} = 1\ \mathrm{cm^3$})$$

Accepted Answer

$$0.80\ \mathrm{g/cm^3$}$$

Question 2

Which of the following numbers is correctly expressed with three significant figures?

Accepted Answer

$$0.00450$$

Question 3

Convert $$0.0250\ \mathrm{kg} to $$milligrams ($$\mathrm{mg}).$$

Accepted Answer

$$2.50 	imes 10^5$\ \mathrm{mg}$$

Question 4

A student needs to convert $$5.0\ \mathrm{cm} to $$meters using dimensional analysis. Which of the following is the correct setup?

Accepted Answer

$$5.0\ \mathrm{cm} 	imes \frac{1\ \mathrm{m}}{100\ \mathrm{cm}}$$

Question 5

A graduated cylinder contains water with a density of $$1.00\ \mathrm{g/cm^3$}. A $$metal object is added, causing the water level to rise from $$25.0\ \mathrm{mL} to$$ $$32.5\ \mathrm{mL}. If $$the mass of the object is $$60.0\ \mathrm{g}$$, what is its density?

Accepted Answer

$$2.67\ \mathrm{g/cm^3$}$$

Question 6

How many molecules are present in $$0.250$$ moles of $$\mathrm{CO_2$}$$? ($$N_A = 6.022 	imes 10$$^{23}$$\ \mathrm{mol}^{-1})$$

Accepted Answer

$$1.51 	imes 10$$^{24}$$ molecules

Question 7

What is the molar mass of $$\mathrm{C_6H_{12}O_6$} ($$glucose)?

Accepted Answer

$$180\ \mathrm{g/mol}$$

Question 8

A compound contains $$40.0\%$$ carbon, $$6.7\%$$ hydrogen, and $$53.3\%$$ oxygen by mass. What is the empirical formula?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 9

How many atoms are present in $$3.00$$ moles of $$\mathrm{Al}$$?

Accepted Answer

$$1.81 	imes 10$$^{24}$$ atoms

Question 10

A sample contains $$12.0$$ grams of $$\mathrm{H_2O}. $$How many moles of water are present?

Accepted Answer

$$0.667$$ moles

Question 11

How many grams of $$\mathrm{NaCl}$$ are produced when $$2.00$$ moles of $$\mathrm{Na}$$ react with excess $$\mathrm{Cl_2$}$$? ($$\mathrm{Na} + \mathrm{Cl_2$} \rightarrow 2\mathrm{NaCl})$$

Accepted Answer

$$117 g$$

Question 12

In the reaction $$2\mathrm{H_2$} + \mathrm{O_2$} \rightarrow 2\mathrm{H_2O}$$, how many moles of $$\mathrm{O_2$}$$ are needed to produce $$4.00$$ moles of $$\mathrm{H_2O}$$?

Accepted Answer

$$2.00$$ moles

Question 13

A reaction has a theoretical yield of $$10.0 g$$, but only $$7.5 g is $$obtained. What is the percent yield?

Accepted Answer

$$75\%$$

Question 14

Which of the following is the correct calculation for mass percent of oxygen in $$\mathrm{H_2O}$$?

Accepted Answer

$$\frac{16.0}{18.0} 	imes 100\%$$

Question 15

If $$3.00$$ moles of $$\mathrm{Fe}$$ react with $$2.00$$ moles of $$\mathrm{O_2$} to $$form $$\mathrm{Fe_2O_3}$$, which is the limiting reactant? ($$4\mathrm{Fe} + 3\mathrm{O_2$} \rightarrow 2\mathrm{Fe_2O_3})$$

Accepted Answer

$$\mathrm{O_2$}$$

Question 16

A solution contains $$5.00 g of$$ $$\mathrm{NaCl}$$ dissolved in $$100.0 g of $$water. What is the mass percent of $$\mathrm{NaCl} in $$the solution?

Accepted Answer

$$4.76\%$$

Question 17

How many moles of $$\mathrm{O}$$ atoms are present in $$2.00$$ moles of $$\mathrm{H_2SO_4}$$?

Accepted Answer

$$8.00$$ moles

Question 18

A chemical reaction produces $$15.0 g of$$ $$\mathrm{CO_2$}$$ from $$10.0 g of$$ $$\mathrm{C}$$ and excess $$\mathrm{O_2$}. $$What is the percent yield if the theoretical yield is $$20.0 g$$?

Accepted Answer

$$75\%$$

Question 19

Which of the following is the correct conversion factor to convert from grams to moles for $$\mathrm{Na_2SO_4}$$?

Accepted Answer

$$\frac{1\ \mathrm{mol}}{142\ \mathrm{g}}$$

Introduction to Chemistry: Conversions, The Mole, and Stoichiometry Study Guide

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