Q: How many molecules are present in 2.00 moles of H$$_2O$$?

$$2.00 \times 6.022 \times 10$$^{23}$$ = 1.2044 \times 10$$^{24}$$ molecules

Q: What is the molar mass of Ca(NO$$_3$$)$$_2$$?

$$40.08 + 2 \times (14.01 + 3 \times 16.00) = 164.10 g/$$mol

Q: In the reaction: 2Al(s) + 3Cl$$_2(g$$) $$\rightarrow 2$$AlCl$$_3(s$$), how many moles of Cl$$_2$$ are required to react with 4.0 moles of Al?

$$4.0 \text{ mol Al} \times \frac{3 \text{ mol Cl}_2}{2 \text{ mol Al}} = 6.0 \text{ mol Cl}_2$$

Q: In a reaction, the actual yield of product is 25.0 g, but the theoretical yield is 40.0 g. What is the percent yield?

$$\frac{25.0}{40.0} \times 100\% = 62.5\%$$

Question 1

Which of the following molecules violates the octet rule in its Lewis structure?

Accepted Answer

BF$$_3$$

Question 2

What is the correct Lewis structure for the nitrate ion (NO$$_3^-$$), and what does this structure demonstrate?

Accepted Answer

It has one double bond and two single bonds, with resonance among the oxygens.

Question 3

Which of the following elements is most likely to form a molecule that obeys the duet rule rather than the octet rule?

Accepted Answer

Hydrogen

Question 4

Given the molecule SF$$_6$$, what is its electron geometry and approximate bond angle?

Accepted Answer

Octahedral, 90$$^\circ$$

Question 5

Which of the following compounds is correctly named using covalent compound prefixes?

Accepted Answer

CO$$_2 is $$carbon dioxide

Question 6

Which statement best explains why water (H$$_2O) is a $$polar molecule?

Accepted Answer

Because oxygen is more electronegative than hydrogen and the molecule is bent.

Question 7

Which of the following is a molecular element?

Accepted Answer

O$$_2$$

Question 8

A chemical equation is balanced when:

Accepted Answer

The number of atoms of each element is the same on both sides of the equation.

Question 9

Which of the following is a precipitation reaction?

Accepted Answer

AgNO$$_3(aq) + $$NaCl(aq) $$\rightarrow$$ AgCl(s) + NaNO$$_3(aq)$$

Question 10

Which ions are spectator ions in the reaction: Na$$_2SO$_4(aq) + $$BaCl$$_2(aq$$) $$\rightarrow$$ BaSO$$_4(s) + 2$$NaCl(aq)?

Accepted Answer

Na$$^+$$ and Cl$$^-$$

Question 11

How many molecules are present in 2.00 moles of H$$_2O$$?

Accepted Answer

$$2.00 	imes 6.022 	imes 10$$^{23}$$ = 1.2044 	imes 10$$^{24}$$ molecules

Question 12

What is the molar mass of Ca(NO$$_3$$)$$_2$$?

Accepted Answer

$$40.08 + 2 	imes (14.01 + 3 	imes 16.00) = 164.10 g/$$mol

Question 13

If 10.0 g of H$$_2O is $$present, how many moles of H$$_2O $$are there? (Molar mass of H$$_2O = 18.02 g/$$mol)

Accepted Answer

$$\frac{10.0}{18.02} = 0.555$$ mol

Question 14

In the reaction: 2Al(s) + 3Cl$$_2(g$$) $$\rightarrow 2$$AlCl$$_3(s$$), how many moles of Cl$$_2$$ are required to react with 4.0 moles of Al?

Accepted Answer

$$4.0 	ext{ mol Al} 	imes \frac{3 	ext{ mol Cl}_2}{2 	ext{ mol Al}} = 6.0 	ext{ mol Cl}_2$$

Question 15

A student mixes 50.0 g of AgNO$$_3 ($$molar mass = 169.87 g/mol) with excess NaCl. What is the theoretical yield of AgCl (molar mass = 143.32 g/mol) produced?

Accepted Answer

$$\frac{50.0}{169.87} = 0.294$$ mol AgNO$$_3$$; 1:1 ratio, so 0.294 mol AgCl; $$0.294 	imes 143.32 = 42.15 g $$AgCl

Question 16

In a reaction, the actual yield of product is 25.0 g, but the theoretical yield is 40.0 g. What is the percent yield?

Accepted Answer

$$\frac{25.0}{40.0} 	imes 100\% = 62.5\%$$

Question 17

Which of the following reactions is an oxidation-reduction (redox) reaction?

Accepted Answer

Zn(s) + CuSO$$_4(aq$$) $$\rightarrow$$ ZnSO$$_4(aq) + Cu(s)$$

Question 18

Which statement best describes the role of electronegativity in polar covalent bonds?

Accepted Answer

A large difference in electronegativity between two atoms causes unequal sharing of electrons.

Question 19

Which of the following is the correct net ionic equation for the reaction between Na$$_2SO$_4(aq) $$and BaCl$$_2(aq$$)?

Accepted Answer

$$	ext{Ba}^{2+}(aq) + 	ext{SO}_4$$^{2-}$$(aq) ightarrow 	ext{BaSO}_4(s)$$

Chemical Bonding, Molecular Geometry, and Chemical Reactions: Study Guide

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