Q: What is the percent by mass of calcium in calcium carbonate ($$CaCO_3$$)? (Atomic masses: Ca = 40.08, C = 12.01, O = 16.00)

$$40.08/100.09 \times 100\% = 40.07\%$$

Question 1

Which of the following best describes the difference between an ionic compound and a molecular compound?

Accepted Answer

Ionic compounds are formed by transferring electrons from metals to nonmetals, while molecular compounds are formed by sharing electrons between nonmetals.

Question 2

Given the molecular formula $$C_6H_{12}O_6$, what is the empirical formula?

Accepted Answer

$$CH_2O$$

Question 3

Which of the following compounds is a salt (ionic compound)?

Accepted Answer

KC$$_2H$_3O$_2$$

Question 4

What is the correct name for the compound Fe$$_2(SO$_4$$)$$_3$$?

Accepted Answer

Iron(III) sulfate

Question 5

Which of the following best explains why ionic solids do not conduct electricity, but their aqueous solutions do?

Accepted Answer

Ions in solids are locked in place and cannot move, but in solution, ions are free to move and carry charge.

Question 6

Calculate the molar mass of capsaicin, $$C_{18}H$$_{27}$$NO_3.$$

Accepted Answer

$$305.41\ \mathrm{g/mol}$$

Question 7

A compound contains 24.5% carbon, 2.04% hydrogen, and 73.5% chlorine by mass. What is the empirical formula?

Accepted Answer

$$CH_2Cl$$

Question 8

Which of the following is the correct Lewis structure for water ($$H_2O$$)?

Accepted Answer

O with two single bonds to H and two lone pairs on O

Question 9

What is the percent by mass of calcium in calcium carbonate ($$CaCO_3$$)? (Atomic masses: Ca = 40.08, C = 12.01, O = 16.00)

Accepted Answer

$$40.08/100.09 	imes 100\% = 40.07\%$$

Question 10

Which of the following best describes lattice energy?

Accepted Answer

The energy released when gaseous ions form an ionic solid.

Question 11

What is the correct name for $$N_2O_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 12

A sample of tartaric acid (C, H, O only) produces 14.08 g CO$$_2$$ and 4.32 g H$$_2O $$upon combustion. What is the first step in determining the empirical formula?

Accepted Answer

Calculate the moles of C and H from the masses of CO$$_2$$ and H$$_2O.$$

Question 13

Which of the following is the correct formula for iron(III) chloride?

Accepted Answer

$$FeCl_3$$

Question 14

How many molecules are in 0.014 g of capsaicin ($$C_{18}H$$_{27}$$NO_3$$, molar mass = 305.41 g/mol)? (Avogadro's number = $$6.022 	imes 10$$^{23}$$)

Accepted Answer

$$2.76 	imes 10$$^{19}$$

Question 15

Which of the following is a correct statement about the octet rule?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve eight electrons in their outer shell.

Question 16

What is the correct name for $$P_4S_{10}$$?

Accepted Answer

Tetraphosphorus decasulfide

Question 17

Which of the following is the correct formula for lithium dichromate?

Accepted Answer

$$Li_2Cr_2O_7$$

Question 18

A compound has an empirical formula of CH and a molar mass of 78.11 g/mol. What is its molecular formula?

Accepted Answer

$$C_6H_6$$

Question 19

Which of the following best describes a hydrate?

Accepted Answer

A compound that contains a specific number of water molecules bound to its atoms.

Chapter 4: Molecules and Compounds – Structured Study Notes

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