Q: Which of the following best describes a mole in chemistry?

A unit that represents $$6.02 \times 10$$^{23}$$ particles, such as atoms, molecules, or ions.

Q: What is the molar mass of $$HCIO_3 ($$hydrochloric acid), given the atomic masses: H = 1.01 g/mol, Cl = 35.45 g/mol, O = 16.00 g/mol?

$$1.01 + 35.45 + (3 \times 16.00) = 84.46 g/$$mol

Q: How many molecules are present in 2.00 moles of water ($$H_2O$$)?

$$2.00 \times 6.02 \times 10$$^{23}$$ = 1.20 \times 10$$^{24}$$ molecules

Question 1

Which of the following best describes a mole in chemistry?

Accepted Answer

A unit that represents $$6.02 	imes 10$$^{23}$$ particles, such as atoms, molecules, or ions.

Question 2

How many moles of hydrogen atoms are present in one mole of sucrose ($$C_{12}H$$_{22}$$O_{11}$)?

Accepted Answer

22 moles

Question 3

What is the molar mass of $$HCIO_3 ($$hydrochloric acid), given the atomic masses: H = 1.01 g/mol, Cl = 35.45 g/mol, O = 16.00 g/mol?

Accepted Answer

$$1.01 + 35.45 + (3 	imes 16.00) = 84.46 g/$$mol

Question 4

If you have 168.92 grams of $$HCIO_3$$, how many moles do you have? (Molar mass = 84.46 g/mol)

Accepted Answer

$$\frac{168.92}{84.46} = 2.00$$ moles

Question 5

Which of the following is an example of a decomposition reaction?

Accepted Answer

$$AB \rightarrow A + B$$

Question 6

A reaction is classified as exothermic if:

Accepted Answer

It releases heat to the surroundings.

Question 7

Which of the following best represents a combustion reaction?

Accepted Answer

$$C_xH_y + O_2$ \rightarrow CO_2$ + H_2O$$

Question 8

In the reaction $$2Al^{3+} + 3Sn$$ \rightarrow 2Al + $$3Sn^{2+}$$, which species is oxidized?

Accepted Answer

Sn

Question 9

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 10

How many molecules are present in 2.00 moles of water ($$H_2O$$)?

Accepted Answer

$$2.00 	imes 6.02 	imes 10$$^{23}$$ = 1.20 	imes 10$$^{24}$$ molecules

Question 11

A patient receives 18.0 g of glucose ($$C_6H_{12}O_6$) intravenously. What is the number of moles administered? (Molar mass = 180.0 g/mol)

Accepted Answer

$$\frac{18.0}{180.0} = 0.100$$ moles

Question 12

Which of the following is the correct balanced equation for the combustion of methane ($$CH_4$$)?

Accepted Answer

$$CH_4 + 2O_2$$ \rightarrow $$CO_2 + 2H_2O$

Question 13

If a reaction absorbs heat from the surroundings, it is classified as:

Accepted Answer

Endothermic

Question 14

Which of the following is the correct mole ratio for the reaction: $$2H_2 + O_2$ \rightarrow 2H_2O$$?

Accepted Answer

2 moles $$H_2$$ : 1 mole $$O_2$$ : 2 moles $$H_2O$$

Question 15

A sample contains $$3.01 	imes 10$$^{23}$$ molecules of CO_2$. How many moles of CO_2$ are present?

Accepted Answer

$$\frac{3.01 	imes 10$$^{23}$$}{6.02 	imes 10$$^{23}$$} = 0.500$$ moles

Question 16

In a redox reaction, which of the following statements is true?

Accepted Answer

The substance that is oxidized loses electrons.

Question 17

A chemical reaction has $$E_{product} = 50 kJ $$and $$E_{reactant} = 100 kJ. $$What is the heat change ($$\Delta E) $$and is the reaction exothermic or endothermic?

Accepted Answer

$$\Delta E = 50 - 100 = -50 kJ$$; exothermic

Question 18

Which of the following best describes a double replacement reaction?

Accepted Answer

$$AB + CD \rightarrow AD + BC$$

Question 19

A student wants to convert 10.0 grams of $$NaCl to $$moles. The molar mass of $$NaCl is 58.44 g/$$mol. What is the correct calculation?

Accepted Answer

$$\frac{10.0}{58.44} = 0.171$$ moles

Question 20

Which of the following is a correct example of a single replacement reaction?

Accepted Answer

$$AB + C \rightarrow AC + B$$

Chemical Quantities and Chemical Reactions: Study Notes

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