GRE Subject Test: Chemistry : Acid-Base Chemistry

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

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Example Questions

Example Question #41 : Acid Base Chemistry

Determine the pH of a  solution of .

Possible Answers:

Correct answer:

Explanation:

 is a strong base and therefore completely ionizes in solution. Therefore, all the  ions dissociate in the  molecules in solutions according to the below chemical equation:

This means that the 

NaOH solution. There is one mole of OHin every mole

of NaOH, therefore:

The equation with the relationship between pH and pOH is below:

We can calculate the pH by rearranging this equation:

Example Question #42 : Acid Base Chemistry

Calculate the Ka for  .

Possible Answers:

Correct answer:

Explanation:

The pka  of  is . The pka is simply calculated based on the following equation:

Therefore, in order to determine the ka, simply use f the following equation:

 

Example Question #43 : Acid Base Chemistry

Calculate the Ka for  .

Possible Answers:

Correct answer:

Explanation:

The pka  of  is . The pka is simply calculated based on the following equation:

Therefore, in order to determine the ka, simply use f the following equation:

Example Question #44 : Acid Base Chemistry

Find the pH of  if its  is  at 

Possible Answers:

Correct answer:

Explanation:

 is a symbol for the ionization constant for water. This value is temperature dependent. At , the  for water is 

Water dissociates or ionizes according to the chemical equation below:

Therefore, the ionization of water results in:

 

Let us set 

Example Question #16 : P H

Find the pH of  if its  is  at 

Possible Answers:

Correct answer:

Explanation:

 is a symbol for the ionization constant for water. This value is temperature dependent. At , the  for water is 

Water dissociates or ionizes according to the chemical equation below:

Therefore, the ionization of water results in:

 

Let us set 

Example Question #45 : Acid Base Chemistry

 

Considering the  for HCN is , what is the  for ?

 

Possible Answers:

Correct answer:

Explanation:

The equilibrium governing the dissolution of HCN in water is:

 is the conjugate acid of . In other words,  is the conjugate base of .

Using the relationship, , we can calculate the .

By rearranging the equation we get:

Example Question #18 : P H

What is the pH of a  solution of ?

Possible Answers:

Correct answer:

Explanation:

We need to calculate the pH of a   solution. There is one mole of  in every mole

of , therefore:

The equation with the relationship between pH and pOH is below:

We can calculate the pH by rearranging this equation:

Another way of solving this problem is shown below. The equation with the relationship between 

and  concentration is:

Rearranging this equation gives:

We can calculate the pH of this solution using the equation below:

Example Question #131 : General Chemistry

What is the pH of a solution in which  concentration is ?

Possible Answers:

Correct answer:

Explanation:

The pH of a solution is related to the number of hydrogen ions in solutions. The equation to determine the pH of a solution is below:

Plugging the concentration given into the equation above gives:

Therefore, the pH of the solution is:

Example Question #132 : General Chemistry

What is the  concentration of a solution with pH ?

Possible Answers:

Correct answer:

Explanation:

The pH of a solution is related to the number of hydrogen ions in solutions. The equation to determine the pH of a solution is below:

The above equation can be converted into the following form in order to determine the hydrogen ion concentration:

Therefore, the hydrogen ion concentration of a solution of pH 7 is:

Example Question #133 : General Chemistry

What is the pH of a solution with a pOH of ?

Possible Answers:

Correct answer:

Explanation:

The equation that expresses the relationship between pH and pOH is:

Plugging the pOH given into the equation above gives:

Rearranging this expression gives:

Therefore, the pH of a solution with a pOH of  is:

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