Q: A 10.8 g sample of dry ice (solid CO$$_2) $$contains how many molecules of CO$$_2$$? (Molar mass of CO$$_2 = 44.01 g/$$mol)

$$1.48 \times 10$$^{23}$$ molecules

Question 1

Which of the following best explains why water (H$$_2O) is a $$liquid at room temperature, while both hydrogen (H$$_2) $$and oxygen (O$$_2) $$are gases under the same conditions?

Accepted Answer

Water molecules experience strong intermolecular forces (hydrogen bonding), while hydrogen and oxygen molecules experience much weaker intermolecular forces.

Question 2

Which of the following is the correct empirical formula for glucose, C$$_6H$_{12}O$_6$$?

Accepted Answer

CH$$_2O$$

Question 3

A sample of a compound contains 0.857 g of hydrogen and 6.86 g of oxygen. What is the empirical formula of the compound?

Accepted Answer

H$$_2O$$

Question 4

Which of the following compounds is an example of a molecular element?

Accepted Answer

O$$_2$$

Question 5

What is the correct name for the compound FeCl$$_3$$?

Accepted Answer

Iron(III) chloride

Question 6

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

Accepted Answer

Ionic compounds involve the transfer of electrons, while molecular compounds involve the sharing of electrons.

Question 7

What is the formula for the compound formed between magnesium ions and nitrate ions?

Accepted Answer

Mg(NO$$_3$$)$$_2$$

Question 8

Which of the following is the correct name for the compound N$$_2O$_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 9

A 10.8 g sample of dry ice (solid CO$$_2) $$contains how many molecules of CO$$_2$$? (Molar mass of CO$$_2 = 44.01 g/$$mol)

Accepted Answer

$$1.48 	imes 10$$^{23}$$ molecules

Question 10

Which of the following is the correct formula for ammonium phosphate?

Accepted Answer

(NH$$_4$$)$$_3PO$_4$$

Question 11

What is the mass percent of carbon in ethane (C$$_2H$_6$$)? (Atomic masses: C = 12.01, H = 1.008)

Accepted Answer

79.85%

Question 12

Which of the following is the correct name for the compound Na$$_2SO$_4$$?

Accepted Answer

Sodium sulfate

Question 13

Which of the following is the correct formula for chromium(III) oxide?

Accepted Answer

Cr$$_2O$_3$$

Question 14

A compound is found to contain 38.7% C, 9.7% H, and 51.6% O by mass. Its molar mass is 62.1 g/mol. What is its molecular formula?

Accepted Answer

C$$_2H$_6O$_2$$

Question 15

Which of the following is a polyatomic ion?

Accepted Answer

NO$$_3^-$$

Question 16

What is the correct name for the acid H$$_2SO$_4$$?

Accepted Answer

Sulfuric acid

Question 17

Which of the following best describes the process of combustion analysis for determining empirical formulas?

Accepted Answer

A compound is burned in oxygen, and the masses of CO$$_2$$ and H$$_2O $$produced are measured to determine the amount of C and H in the original sample.

Question 18

Which of the following is the correct formula for zinc sulfate?

Accepted Answer

ZnSO$$_4$$

Question 19

Which of the following is the correct name for the hydrate CoCl$$_2$$·6H$$_2O$$?

Accepted Answer

Cobalt(II) chloride hexahydrate

Question 20

Which of the following is the correct formula for potassium carbonate?

Accepted Answer

K$$_2CO$_3$$

Chapter 3: Molecules and Compounds – Study Notes for General Chemistry

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