Q: If $$2.0$$ moles of $$\mathrm{O_2$}$$ are required for a reaction, how many molecules of $$\mathrm{O_2$}$$ does this represent?

$$1.20 \times 10$$^{24}$$ molecules

Q: A mixture contains $$2$$ moles of $$\mathrm{N_2$}$$ and $$3$$ moles of $$\mathrm{O_2$}. $$What is the total number of molecules in the mixture?

$$3.01 \times 10$$^{24}$$ molecules

Question 1

Which of the following correctly describes the octet rule as it applies to chemical bonding?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve a total of eight electrons in their outermost shell.

Question 2

Given the following ions: $$\mathrm{Na^+}$$, $$\mathrm{Cl^-}$$, $$\mathrm{Ca$$^{2+}$$}$$, and $$\mathrm{O$$^{2-}$$}$$, which combination will form an ionic compound with a 1:1 ratio?

Accepted Answer

$$\mathrm{Na^+}$$ and $$\mathrm{Cl^-}$$

Question 3

Which of the following molecules is polar due to its molecular geometry and electronegativity difference?

Accepted Answer

$$\mathrm{H_2O}$$

Question 4

A patient is given a medication containing $$\mathrm{Na_2SO_4}. $$What is the correct name for this compound?

Accepted Answer

Sodium sulfate

Question 5

Which of the following is the correct Lewis structure for $$\mathrm{CO_2$}$$?

Accepted Answer

O=C=O, with each oxygen having two lone pairs

Question 6

Which of the following polyatomic ions has a charge of $$-3$$?

Accepted Answer

$$\mathrm{PO_4$^{3-}}$$

Question 7

A sample contains $$3.01 	imes 10$$^{23}$$ molecules of $$\mathrm{H_2O}$$. How many moles of water are present?

Accepted Answer

$$0.5$$ moles

Question 8

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons, while covalent bonds involve the sharing of electrons.

Question 9

A gas sample at STP has a volume of $$22.4 L. $$How many moles of gas does it contain?

Accepted Answer

$$1$$ mole

Question 10

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

Accepted Answer

$$\mathrm{(NH_4$)_3PO_4}$$

Question 11

If $$2.0$$ moles of $$\mathrm{O_2$}$$ are required for a reaction, how many molecules of $$\mathrm{O_2$}$$ does this represent?

Accepted Answer

$$1.20 	imes 10$$^{24}$$ molecules

Question 12

Which of the following is NOT a correct use of the Combined Gas Law?

Accepted Answer

Calculating the number of moles of gas when pressure, volume, and temperature change.

Question 13

A mixture contains $$2$$ moles of $$\mathrm{N_2$}$$ and $$3$$ moles of $$\mathrm{O_2$}. $$What is the total number of molecules in the mixture?

Accepted Answer

$$3.01 	imes 10$$^{24}$$ molecules

Question 14

Which of the following statements about partial pressure is correct?

Accepted Answer

The partial pressure of a gas in a mixture is the pressure it would exert if it occupied the entire volume alone.

Question 15

Which of the following is the correct balanced chemical equation for the combustion of methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

$$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}$$

Question 16

A balloon contains $$0.5$$ moles of $$\mathrm{He}$$ gas at STP. What is its volume?

Accepted Answer

$$11.2 L$$

Question 17

Which of the following is the correct formula for calcium hydroxide?

Accepted Answer

$$\mathrm{Ca(OH)_2}$$

Question 18

Which of the following best explains why $$\mathrm{CO_2$} is a $$nonpolar molecule even though it contains polar bonds?

Accepted Answer

The molecule is linear and the dipoles cancel each other out.

Question 19

A sample of gas has a pressure of $$2.0$$ atm, a volume of $$4.0 L$$, and a temperature of $$300 K. $$Using the ideal gas law $$P V = n R T$$, how many moles of gas are present? ($$R = 0.0821 L $$atm / mol K)

Accepted Answer

$$0.33$$ moles

Study Guide: Chemical Bonding, Nomenclature, and Chemical Calculations

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