GRE Subject Test: Chemistry : Acid-Base Analysis

Study concepts, example questions & explanations for GRE Subject Test: Chemistry

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Example Questions

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Example Question #11 : Acid Base Analysis

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Based on the equilibrium above, what does  act as? 

Possible Answers:

an anion

a base

radical

an acid

a catalyst

Correct answer:

an acid

Explanation:

An acid is a substance that can donates a proton. The conjugate acid of a base is formed when the base accepts a proton. In this case,  is the conjugate acid to the base . This is because  accepts a hydrogen ion from the water molecule to form , the conjugate acid.

Example Question #11 : Analyzing Reactions

Given the following equilibria, what is the hydroxide ion concentration of a solution containing  ?

The  for  is 

Possible Answers:

Correct answer:

Explanation:

Below is the acid-base equilibria of  in an aqueous solution:

A solution of ammonia () is basic based on the chemical equation given. The  for this reaction is:

Based on the chemical equation, 

We can make the concentration of these species equal to :

The  concentration is equal to:

 has a low  so we can assume the following:

Plugging the values into the base dissociation constant equation gives:

Solve for

Example Question #11 : Analyzing Reactions

Given the following equilibria, what is the hydrogen ion concentration of a solution containing   (benzoic acid)?

The  for  is .

Possible Answers:

Correct answer:

Explanation:

Below is the acid-base equilibria of  in an aqueous solution:

A solution of benzoic acid () is acidic based on the chemical equation given. The  for this reaction is:

Based on the chemical equation, 

We can make the concentration of these species equal to :

The  concentration is equal to:

 has a low  so we can assume the following:

Plugging the values into the base dissociation constant equation gives:

Solve for

Example Question #11 : Acid Base Analysis

Given the following equilibria, what is the hydronium ion concentration of a solution containing  ?

The  for  is .

Possible Answers:

Correct answer:

Explanation:

Below is the acid-base equilibria of  in an aqueous solution:

A solution of  is acidic based on the chemical equation given. The Ka for this reaction is:

Based on the chemical equation, 

We can make the concentration of these species equal to :

The  concentration is equal to:

 has a low  so we can assume the following:

Plugging the values into the base dissociation constant equation gives:

Solve for

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