Q: How many molecules are in $$5.0$$ moles of $$\mathrm{CO_2$}$$?

$$3.0 \times 10$$^{24}$$ molecules

Q: A $$325 mg $$tablet of aspirin ($$\mathrm{C_9H_8O_4}$$, molar mass $$180.2 g/$$mol) contains how many molecules of aspirin?

$$1.09 \times 10$$^{21}$$ molecules

Question 1

Which of the following best describes a chemical change?

Accepted Answer

A conversion of one substance into another, involving breaking and forming chemical bonds.

Question 2

Which equation represents the balanced chemical reaction for the combustion of propane ($$\mathrm{C_3H_8}$$)?

Accepted Answer

$$\mathrm{C_3H_8} + 5\mathrm{O_2$} \rightarrow 3\mathrm{CO_2$} + 4\mathrm{H_2O}$$

Question 3

According to the law of conservation of mass, which statement is true about a balanced chemical equation?

Accepted Answer

The number of atoms of each element is the same on both sides of the equation.

Question 4

What is the formula weight of $$\mathrm{$$FeSO_4$$}$$ given the atomic weights: Fe = 55.845 amu, S = 32.066 amu, O = 15.999 amu?

Accepted Answer

$$151.877$$ amu

Question 5

How many molecules are in $$5.0$$ moles of $$\mathrm{CO_2$}$$?

Accepted Answer

$$3.0 	imes 10$$^{24}$$ molecules

Question 6

A $$325 mg $$tablet of aspirin ($$\mathrm{C_9H_8O_4}$$, molar mass $$180.2 g/$$mol) contains how many molecules of aspirin?

Accepted Answer

$$1.09 	imes 10$$^{21}$$ molecules

Question 7

How many moles of $$\mathrm{CO}$$ are produced from $$3.5$$ moles of $$\mathrm{C_2H_6} in $$the reaction $$2\mathrm{C_2H_6} + 5\mathrm{O_2$} \rightarrow 4\mathrm{CO} + 6\mathrm{H_2O}$$?

Accepted Answer

$$7.0$$ moles

Question 8

Using the balanced equation $$3\mathrm{O_2$} \rightarrow 2\mathrm{O_3$}$$, how many grams of ozone ($$\mathrm{O_3$}$$, molar mass $$48.0 g/$$mol) are formed from $$9.0$$ moles of $$\mathrm{O_2$}$$?

Accepted Answer

$$290 g$$

Question 9

Ethanol ($$\mathrm{C_2H_6O}$$, molar mass $$46.1 g/$$mol) is synthesized from $$14 g of $$ethylene ($$\mathrm{C_2H_4}$$, molar mass $$28.1 g/$$mol). How many grams of ethanol are formed?

Accepted Answer

$$23 g$$

Question 10

If the theoretical yield of ethanol in a reaction is $$23 g$$, but only $$15 g is $$actually obtained, what is the percent yield?

Accepted Answer

$$65\%$$

Question 11

In the reaction $$2\mathrm{H_2$} + \mathrm{O_2$} \rightarrow 2\mathrm{H_2O}$$, if you start with $$4$$ molecules of $$\mathrm{H_2$}$$ and $$1$$ molecule of $$\mathrm{O_2$}$$, which is the limiting reactant?

Accepted Answer

$$\mathrm{O_2$}$$

Question 12

Which of the following statements about oxidation and reduction is correct?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 13

In the reaction $$\mathrm{Zn} + \mathrm{Cu$$^{2+}$$} \rightarrow \mathrm{Zn$$^{2+}$$} + \mathrm{Cu}$$, which species is oxidized?

Accepted Answer

$$\mathrm{Zn}$$

Question 14

Which compound acts as the reducing agent in the reaction $$\mathrm{Zn} + \mathrm{Cu$$^{2+}$$} \rightarrow \mathrm{Zn$$^{2+}$$} + \mathrm{Cu}$$?

Accepted Answer

$$\mathrm{Zn}$$

Question 15

Which of the following is NOT a symbol used in chemical equations?

Accepted Answer

$$(p)$$ for plasma

Question 16

What is the molar mass of carbon, given its atomic weight is $$12.01$$ amu?

Accepted Answer

$$12.01 g/$$mol

Question 17

Which of the following is a correct mole ratio for the reaction $$\mathrm{N_2$} + \mathrm{O_2$} \rightarrow 2\mathrm{NO}$$?

Accepted Answer

$$1$$ mol $$\mathrm{N_2$}$$ : $$2$$ mol $$\mathrm{NO}$$

Question 18

Which process results in the gain of oxygen atoms and loss of hydrogen atoms?

Accepted Answer

Oxidation

Chapter 5: Chemical Reactions – Principles, Calculations, and Applications

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