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

A mole is 6.022 \times $$10^{23}$$ particles of a substance.

Q: How many atoms are present in 3.00 mol of carbon atoms?

$$3.00 \times 6.022 \times 10$$^{23}$$ = 1.81 \times 10$$^{24}$$ atoms

Q: A sample contains $$1.20 \times 10$$^{24}$$ atoms of sodium. How many moles of sodium are present?

$$1.20 \times 10$$^{24}$$ / 6.022 \times 10$$^{23}$$ = 1.99$$ mol

Q: What is the molecular weight (molar mass) of glucose ($$C_6H_{12}O_6$)?

$$6 \times 12.01 + 12 \times 1.01 + 6 \times 16.00 = 180.18 g/$$mol

Q: How many moles of glucose are present in a 90.0 g sample of glucose ($$C_6H_{12}O_6$)?

$$90.0 \text{ g} / 180.18 \text{ g/mol} = 0.499$$ mol

Question 1

Which of the following best describes a mole in chemistry?

Accepted Answer

A mole is 6.022 	imes $$10^{23}$$ particles of a substance.

Question 2

How many atoms are present in 3.00 mol of carbon atoms?

Accepted Answer

$$3.00 	imes 6.022 	imes 10$$^{23}$$ = 1.81 	imes 10$$^{24}$$ atoms

Question 3

A sample contains $$1.20 	imes 10$$^{24}$$ atoms of sodium. How many moles of sodium are present?

Accepted Answer

$$1.20 	imes 10$$^{24}$$ / 6.022 	imes 10$$^{23}$$ = 1.99$$ mol

Question 4

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

Accepted Answer

$$6 	imes 12.01 + 12 	imes 1.01 + 6 	imes 16.00 = 180.18 g/$$mol

Question 5

How many moles of glucose are present in a 90.0 g sample of glucose ($$C_6H_{12}O_6$)?

Accepted Answer

$$90.0 	ext{ g} / 180.18 	ext{ g/mol} = 0.499$$ mol

Question 6

Which of the following is NOT a characteristic of organic compounds?

Accepted Answer

They are primarily composed of ionic bonds.

Question 7

Which of the following is the correct Lewis structure for methane ($$CH_4$$)?

Accepted Answer

A central carbon atom with four single bonds to four hydrogen atoms.

Question 8

Which of the following is the correct order for drawing a Lewis dot structure?

Accepted Answer

Count valence electrons, determine central atom, connect with single bonds, add remaining electrons to outer atoms, check octet, add remaining electrons to central atom, form multiple bonds if needed.

Question 9

Which of the following best describes an alkane?

Accepted Answer

A hydrocarbon with only single bonds between carbon atoms.

Question 10

What is the molecular formula for butane?

Accepted Answer

$$C_4H_{10}$$

Question 11

Which of the following is the correct condensed structure for pentane?

Accepted Answer

$$CH_3CH_2CH_2CH_2CH_3$$

Question 12

Which of the following is the correct name for a six-carbon ring alkane?

Accepted Answer

Cyclohexane

Question 13

Which of the following statements about alkanes is TRUE?

Accepted Answer

Alkanes are nonpolar because the electronegativities of carbon and hydrogen are similar.

Question 14

What is the correct prefix for an alkane with 8 carbon atoms?

Accepted Answer

Oct-

Question 15

Which of the following is the correct skeletal structure for propane?

Accepted Answer

A zigzag line with three vertices (two bends)

Question 16

Which of the following is the correct molecular formula for cyclopentane?

Accepted Answer

$$C_5H_{10}$$

Question 17

Which of the following is a correct comparison between condensed, molecular, and skeletal structures?

Accepted Answer

Molecular formula shows only the number of each atom, condensed structure shows connectivity without all bonds, skeletal structure shows only the carbon backbone.

Question 18

Which of the following is the correct number of valence electrons for carbon?

Accepted Answer

4

Question 19

Which of the following is the correct formula for calculating the number of moles from a given mass and molar mass?

Accepted Answer

$$	ext{moles} = \frac{	ext{mass (g)}}{	ext{molar mass (g/mol)}}$$

Organic Chemistry Study Notes: Introduction, Molecular Representations, and Alkanes

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