Buffers

Multiple Choice

What is the normal pH range of the human blood?

• 7.25-8.0

• 3.30-3.45

• 7.3 - 7.45

• 7.0-7.25

Multiple Choice

What will happen to the pH of the blood if there is a higher concentration of carbon dioxide? It will become...

• More acidic

• More alkaline

• Neutral

• Buffer

Multiple Choice

To maintain the pH of the blood to 7.3 - 7.45, which of the following will happen if there is an excess of OH^-?

• HCO₃^– + H⁺ $$\rightarrow$$ H₂CO₃

• H₂CO₃ + OH $$\rightarrow$$ HCO₃^– + H₂O

• H₂CO₃ $$\rightarrow$$ CO₂ + H₂O

• CO₂ + H₂O $$\rightarrow$$ H₂CO₃

REVIEW

Multiple Choice

What do you call the product that will be formed after a base accepts H⁺?

• Bronsted acid

• Bronsted base

• Conjugate base

• Conjugate acid

Multiple Choice

What do you call the product that will be formed after an acid loses H⁺?

• Bronsted acid

• Bronsted base

• Conjugate base

• Conjugate acid

Multiple Choice

Which of the following is not TRUE about buffers?

• it contains a weak acid and its

  conjugate base

• it can absorb excess H⁺ ions or OH^– ions

• maintaining an overall steady pH

• it is formed when a proton is removed from an acid

Multiple Choice

How can a buffer maintain the pH of a solution when acid is added?

• the conjugate base of the buffer neutralizes the acid

• the conjugate base of the buffer neutralizes the base

• the conjugate acid of the buffer neutralizes the base added

• the conjugate acid of the buffer neutralizes the base acid

Multiple Choice

How can a buffer maintain the pH of a solution when acid is added?

• the conjugate base of the buffer neutralizes the acid

• the conjugate base of the buffer neutralizes the base

• the conjugate acid of the buffer neutralizes the base added

• the conjugate acid of the buffer neutralizes the base acid

Multiple Choice

How can a buffer maintain the pH when base is added to the solution?

• the conjugate base of the buffer neutralizes the acid added

• the conjugate base of the buffer neutralizes the base added

• the conjugate acid of the buffer neutralizes the base added

• the conjugate acid of the buffer neutralizes the acid added

Multiple Choice

Which equation is used calculate the specific pH of a given buffer?

• Henderson-Hasselbalch

• Lowry-Bronsted

• Arrhenius

• Henderson-Hasslebalch

Match

Match the following.

• the concentration of [H⁺]

• the "dissociation constant" for the weak acid

• the concentration of conjugate base

• the concentration of the weak acid

pH

K_a

[A^-]

[HA]

• pH

• K_a

• [A^-]

• [HA]

Multiple Choice

To calculate the specific pH of a given buffer, you need to use the Henderson-Hasselbalch equation for acidic buffers:

• 𝑝𝐾_𝑎 + 𝑙𝑜𝑔 $$\frac{\left[A^-\right]}{\left[HA\right]}$$

• 𝑝𝐾_𝑎 + 𝑙𝑜𝑔 $$\frac{\left[B^+\right]}{\left[BOH\right]}$$

• 𝑝𝐾_𝑎 + 𝑙𝑜𝑔 $$\frac{\left[conjugate\ acid\right]}{\left[weak\ base\right]}$$

• -logK_a

Match

Match the following.

• the concentration of [H⁺]

• the "dissociation constant" for the weak base

• the concentration of conjugate acid

• the concentration of the weak base

pH

K_b

[A⁺]

[BOH]

• pH

• K_b

• [A⁺]

• [BOH]

Fill in the Blank

Calculate the pH of a buffer made from 0.28 M HNO₂ and 0.23 M NO₂^-. The K_a for HNO₂ is 4.6×10^-4

.

Fill in the Blank

What is the pH of the solution containing 0.20 M NH₃ and 0.15 M NH₄⁺?

Given the pKa for NH₄⁺ is 9.25

.

EVALUATION

Multiple Choice

A buffer is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa.

• True

• False

Multiple Choice

A conjugate acid is a species formed by the gain of a proton by a base while in reverse, a conjugate base is a species formed by the removal of a proton from an acid.

• True

• False

Multiple Choice

The Henderson-Hasselbalch equation can be used to calculate the specific pH of a given buffer.

• True

• False

Multiple Choice

If an acid is added to the substance, the conjugate base of the buffer neutralizes the acid added. If a base is added to the substance, the conjugate acid of the buffer neutralizes the base added.

• True

• False