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Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry
Bruice - Organic Chemistry 8th Edition
Bruice8th EditionOrganic ChemistryISBN: 9780135213711당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Bruice 8th EditionCh. 2 - Acids and Bases: Central to Understanding Organic Chemistry문제 68a
2장, 문제 68a

For each of the following pairs of reactions, indicate which one has the more favorable equilibrium constant (that is, which one most favors products):
1. Chemical equilibrium reactions showing two pairs of acid-base reactions with their respective products and reactants.
2. Chemical equilibrium reactions showing the interaction of ethanol with ammonia and methylamine, indicating product favorability.

검증된 단계별 안내
1
Step 1: Understand the problem. The question asks us to compare the equilibrium constants for two pairs of reactions. The equilibrium constant depends on the relative acidity of the acids involved, which can be determined using their pKa values. Lower pKa values indicate stronger acids.
Step 2: Analyze the first pair of reactions: CH3CH2OH + NH3 ⇌ CH3CH2O− + NH4 and CH3OH + NH3 ⇌ CH3O− + NH4. Compare the acidity of CH3CH2OH and CH3OH using their pKa values. CH3CH2OH has a slightly higher pKa than CH3OH, meaning CH3OH is the stronger acid. Therefore, the reaction involving CH3OH will have a more favorable equilibrium constant.
Step 3: Analyze the second pair of reactions: CH3CH2OH + NH3 ⇌ CH3CH2O− + NH4 and CH3CH2OH + CH3NH2 ⇌ CH3CH2O− + CH3NH3+. Compare the acidity of NH4+ and CH3NH3+ using their pKa values. NH4+ has a lower pKa (9.40) compared to CH3NH3+ (10.70), meaning NH4+ is the stronger acid. Therefore, the reaction involving NH4+ will have a more favorable equilibrium constant.
Step 4: Summarize the reasoning. For each pair of reactions, the equilibrium constant favors the reaction where the acid involved is stronger (lower pKa). This is because stronger acids donate protons more readily, driving the equilibrium toward the products.
Step 5: Conclude the comparison. For the first pair, the reaction with CH3OH is more favorable. For the second pair, the reaction with NH4+ is more favorable. Use the provided pKa table to justify these conclusions.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
4m

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Equilibrium Constant (K)

The equilibrium constant (K) quantifies the ratio of the concentrations of products to reactants at equilibrium for a reversible reaction. A larger K value indicates a greater favorability for the formation of products, while a smaller K suggests that reactants are favored. Understanding K is crucial for predicting the direction of a reaction and its extent.
추천 영상:
02:19
The relationship between equilibrium constant and pKa.

pKa and Acid Strength

pKa is a measure of the strength of an acid in solution; it is the negative logarithm of the acid dissociation constant (Ka). Lower pKa values correspond to stronger acids, which dissociate more completely in solution. In acid-base reactions, the relative pKa values of the acids involved can help predict which direction the equilibrium will favor.
추천 영상:
07:45
Identifying pKa values

Acid-Base Reactions

Acid-base reactions involve the transfer of protons (H+) from an acid to a base. The strength of the acids and bases involved determines the position of equilibrium. In the context of the given reactions, comparing the pKa values of the acids (like CH3OH and CH3CH2OH) helps to ascertain which reaction will favor product formation more strongly.
추천 영상:
02:49
The Lewis definition of acids and bases.
관련 실천
교과서 질문

From which of the following compounds can HO− remove a proton in a reaction that favors product formation?

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교과서 질문

Tenormin, a member of the group of drugs known as beta-blockers, is used to treat high blood pressure and improve survival after a heart attack. It works by slowing down the heart to reduce its workload. Which atom in Tenormin is the most basic?

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교과서 질문

a. Without using a calculator, estimate the pH of each of the following solutions:

1. [HO−] = 3.2 × 10−5

2. [H3O+] = 8.3 × 10−1

3. [H3O+] = 1.7 × 10−3

b. Determine the exact pH, using a calculator.

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교과서 질문

b. Determine the exact pKa values, using a calculator.

c. Which is the strongest acid?

1. nitrous acid (HNO2), Ka = 4.0 × 10−4

2. nitric acid (HNO3), Ka = 22

3. bicarbonate (HCO3−), Ka = 6.3 × 10−11

4. hydrogen cyanide (HCN), Ka = 7.9 × 10−10

5. formic acid (HCOOH), Ka = 2.0 × 10−4

6. phosphoric acid (H3PO4), Ka = 2.1

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교과서 질문

You are planning to carry out a reaction that produces protons. The reaction will be buffered at pH = 10.5. Would it be better to use a protonated methylamine/methylamine buffer or a protonated ethylamine/ethylamine buffer? (pKa of protonated methylamine = 10.7; pKa of protonated ethylamine = 11.0)

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교과서 질문

Which of the four reactions has the most favorable equilibrium constant?

1.

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