Textbook Question
Given the value of Keq for the following acid–base reactions, identify the weakest acid and the weakest base.
(c)
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3. Acids and Bases
Acid Base Equilibrium
1:56 minutesProblem 28
Textbook Question
Given the following Keq values, how much stronger of an acid is methanol (CH3OH) than acetylene (HC≡CH)?
Verified step by step guidance1
Identify the equilibrium constant (K_eq) values for methanol (CH₃OH) and acetylene (HC≡CH). These values are typically related to the acid dissociation constants (K_a) of the acids.
Recall that the strength of an acid is directly proportional to its K_a value. A higher K_a indicates a stronger acid.
To compare the acid strengths, calculate the ratio of the K_a values of methanol to acetylene. This can be expressed as:
Take the logarithm (base 10) of the ratio to express the difference in acid strength in terms of pKa values. Recall that .
Interpret the result: A difference of 1 in pKa corresponds to a 10-fold difference in acid strength. Use this relationship to determine how much stronger methanol is as an acid compared to acetylene.
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1mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acid-Base Strength
Acid-base strength is determined by the ability of an acid to donate protons (H⁺) in a solution. Stronger acids have a greater tendency to dissociate and release protons, leading to higher concentrations of H⁺ ions. The strength of an acid can be quantitatively expressed using the acid dissociation constant (K_a), where a larger K_a indicates a stronger acid.
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Acid-Base Catalysis Concept 3
Equilibrium Constant (K_eq)
The equilibrium constant (K_eq) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction. In acid-base reactions, K_eq can be used to compare the strengths of different acids. A higher K_eq value for an acid indicates that it is more likely to donate protons compared to another acid, thus being stronger.
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02:19The relationship between equilibrium constant and pKa.
Comparative Acid Strength
To compare the strength of two acids, one can use the relationship between their K_a values or K_eq values. The difference in their K_eq values can be used to calculate how many times stronger one acid is compared to another. This comparison is essential in organic chemistry to predict the behavior of acids in various chemical reactions and their reactivity.
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02:41Comparing hydrocarbon acidity
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