Q: How many molecules are in 18.0 g of water (H$$_2O$$)? (Use $$N_A = 6.022 \times 10$$^{23}$$ mol$$^{-1}$$)

$$6.022 \times 10$$^{23}$$ molecules$

Question 1

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

Accepted Answer

Ionic compounds are composed of cations and anions held together by electrostatic forces, while molecular compounds are composed of nonmetals held together by covalent bonds.

Question 2

Which of the following is a molecular element?

Accepted Answer

O$$_2$$

Question 3

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

Accepted Answer

Iron(III) sulfate

Question 4

What is the formula for dinitrogen pentoxide?

Accepted Answer

N$$_2O$_5$$

Question 5

Calculate the molar mass of calcium nitrate, Ca(NO$$_3$$)$$_2.$$

Accepted Answer

$$164.10\ \mathrm{g/mol}$$

Question 6

How many molecules are in 18.0 g of water (H$$_2O$$)? (Use $$N_A = 6.022 	imes 10$$^{23}$$ mol$$^{-1}$$)

Accepted Answer

$$6.022 	imes 10$$^{23}$$ molecules$

Question 7

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?

Accepted Answer

CH$$_2O$$

Question 8

Balance the following equation: $$ \mathrm{C_3H_8 + O_2 \rightarrow CO_2 + H_2O} $$

Accepted Answer

$$\mathrm{C_3H_8 + 5\ O_2$ \rightarrow 3\ CO_2$ + 4\ H_2O}$$

Question 9

If 10.0 g of H$$_2$$ reacts with 80.0 g of O$$_2 to $$form water, what is the limiting reactant?

Accepted Answer

H$$_2$$

Question 10

A reaction has a theoretical yield of 50.0 g but produces only 42.0 g of product. What is the percent yield?

Accepted Answer

$$84.0\%$$

Question 11

Which of the following compounds is most likely to be soluble in water?

Accepted Answer

NaCl

Question 12

What is the net ionic equation for the reaction between aqueous solutions of Na$$_2SO$_4$$ and BaCl$$_2$$?

Accepted Answer

$$\mathrm{Ba$$^{2+}$$ (aq) + SO_4$^{2-} (aq) \rightarrow $$BaSO_4$$ (s)}$$

Question 13

What is the molarity of a solution prepared by dissolving 5.00 g of NaCl in enough water to make 250.0 mL of solution? (Molar mass NaCl = 58.44 g/mol)

Accepted Answer

$$0.342\ \mathrm{M}$$

Question 14

Which of the following is a nonelectrolyte?

Accepted Answer

C$$_6H$_{12}O$_6 ($$glucose)

Question 15

What is the oxidation state of sulfur in H$$_2SO$_4$$?

Accepted Answer

+6

Question 16

Which of the following reactions is a redox reaction?

Accepted Answer

$$\mathrm{2Na (s) + Cl_2$ (g) \rightarrow 2NaCl (s)}$$

Question 17

A 25.0 mL sample of 0.200 M HCl is titrated with 0.100 M NaOH. What volume of NaOH is required to reach the equivalence point?

Accepted Answer

$$50.0\ \mathrm{mL}$$

Question 18

Which of the following is the correct molecular equation for the reaction between hydrochloric acid and sodium hydroxide?

Accepted Answer

$$\mathrm{HCl (aq) + NaOH (aq) \rightarrow NaCl (aq) + H_2O (l)}$$

Exam 2 Study Guide: Molecules, Compounds, and Chemical Reactions

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