Q: Which of the following statements about formal charge is correct?

Formal charge is calculated as: $$\text{Valence electrons} - (\text{Non-bonding electrons} + \frac{1}{2}\text{Bonding electrons})$$

Question 1

Which of the following correctly assigns the formal charge to the nitrogen atom in the molecule $$\ce{NH4+}$$?

Accepted Answer

$$+1$$

Question 2

Given the molecule $$\ce{CH3O^-}$$, what is the hybridization of the oxygen atom's lone pairs?

Accepted Answer

$$sp^3$$

Question 3

Which of the following molecules is polar?

Accepted Answer

$$\ce{CH3F}$$

Question 4

In the acid-base reaction between acetic acid ($$\ce{CH3COOH}) $$and hydroxide ion ($$\ce{OH^-}$$), which of the following is the correct conjugate base?

Accepted Answer

$$\ce{CH3COO^-}$$

Question 5

Which of the following best describes the orbital overlap in the bond between carbon and chlorine in $$\ce{CH3Cl}$$?

Accepted Answer

$$sp^3 (C) $$and $$3p (Cl)$$

Question 6

Which of the following statements about formal charge is correct?

Accepted Answer

Formal charge is calculated as: $$	ext{Valence electrons} - (	ext{Non-bonding electrons} + \frac{1}{2}	ext{Bonding electrons})$$

Question 7

Which of the following correctly matches the acid and its conjugate base in the reaction: $$\ce{H2O + NH3 \rightarrow OH^- + NH4^+}$$?

Accepted Answer

Acid: $$\ce{H2O}$$, Conjugate base: $$\ce{OH^-}$$

Question 8

Which of the following molecules has a net dipole moment?

Accepted Answer

$$\ce{CH2Cl2}$$

Question 9

If the $$pK_a of $$acetic acid is $$4.8$$ and the $$pK_a of $$phenol is $$10.0$$, which is the stronger acid and why?

Accepted Answer

Acetic acid, because a lower $$pK_a$$ indicates a stronger acid.

Question 10

Which of the following best describes the hybridization of the central atom in $$\ce{CO2}$$?

Accepted Answer

$$sp$$

Question 11

A student is asked to draw the curved-arrow mechanism for the deprotonation of ethanol ($$\ce{CH3CH2OH}) by $$sodium hydride ($$\ce{NaH}). $$Which of the following best describes the first step?

Accepted Answer

A lone pair from $$\ce{H^-}$$ attacks the hydrogen of the $$\ce{OH}$$ group, forming $$\ce{H2}$$ and leaving $$\ce{CH3CH2O^-}.$$

Question 12

Which of the following is the correct order of increasing acidity for the following compounds: $$\ce{CH4}$$, $$\ce{NH3}$$, $$\ce{H2O}$$, $$\ce{HF}$$?

Accepted Answer

$$\ce{CH4} \u003c \ce{NH3} \u003c \ce{H2O} \u003c \ce{HF}$$

Question 13

Which of the following best explains why $$\ce{CH3F} is $$polar while $$\ce{CF4} is $$not?

Accepted Answer

$$\ce{CH3F}$$ has an asymmetric distribution of charge, while $$\ce{CF4} is $$tetrahedral and symmetric.

Question 14

In the reaction between $$\ce{CH3COOH}$$ and $$\ce{OH^-}$$, what is the direction of the equilibrium?

Accepted Answer

Toward the formation of $$\ce{CH3COO^-}$$ and $$\ce{H2O}$$

Question 15

Which of the following is the correct Lewis structure for $$\ce{NO3^-} ($$nitrate ion) in terms of formal charges?

Accepted Answer

One oxygen with $$-1$$ formal charge, nitrogen with $$+1$$, and two oxygens with $$0.$$

Question 16

Which of the following best describes the acid-base relationship between $$\ce{NH4^+}$$ and $$\ce{NH3}$$?

Accepted Answer

$$\ce{NH4^+} is $$the conjugate acid of $$\ce{NH3}$$

Question 17

Which of the following is the correct $$pK_a$$ range for a carboxylic acid?

Accepted Answer

$$4-5$$

Question 18

A molecule has a central atom with two double bonds and no lone pairs. What is the hybridization of the central atom?

Accepted Answer

$$sp$$

Question 19

Which of the following best explains why $$\ce{H2O} is $$more acidic than $$\ce{NH3}$$?

Accepted Answer

Oxygen is more electronegative than nitrogen, stabilizing the negative charge on the conjugate base.

Organic Chemistry: Atomic Structure, Formal Charge, Hybridization, Polarity, and Acid-Base Equilibria

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