Understanding Polyprotic Acids and Titration Curves

The video tutorial explains polyprotic acids, focusing on the amino acid alanine. It covers the titration process with sodium hydroxide, analyzing the titration curve, and identifying equivalence and half equivalence points. The tutorial also discusses buffer regions and the Henderson-Hasselbalch equation, highlighting the significance of pKa values in understanding the acidity of protons in diprotic acids.

What is a polyprotic acid?

• An acid that donates electrons

• An acid that cannot donate any protons

• An acid with more than one proton to donate

• An acid that can donate only one proton

Which form of alanine is used as an example of a polyprotic acid?

• Basic form

• Protonated form

• Neutral form

• Deprotonated form

During the titration of alanine, which proton is neutralized first?

• Proton on the sulfur

• Proton on the oxygen

• Proton on the carbon

• Proton on the nitrogen

What is the significance of the first equivalence point in a titration curve?

• The solution becomes acidic

• The first acidic proton is completely neutralized

• The solution becomes basic

• All acidic protons are neutralized

What happens at the half equivalence point during titration?

• The solution becomes saturated

• The pH is at its lowest

• The concentration of acid equals the concentration of its conjugate base

• The solution is fully neutralized

What is the pH at the first half equivalence point equal to?

• The pH of pure water

• The pKa of the more acidic proton

• The pH of the solution

• The pKa of the less acidic proton

What occurs at the second equivalence point in the titration of alanine?

• The first acidic proton is neutralized

• The second acidic proton is neutralized

• The solution becomes acidic

• The solution becomes basic

How many moles of hydroxide ions are needed to reach the second equivalence point?

• One mole

• Three moles

• Half a mole

• Two moles

What does the number of equivalence points in a titration curve indicate?

• The number of electrons

• The number of neutral protons

• The number of acidic protons

• The number of basic protons

What is the relationship between the number of acidic protons and equivalence points in a titration curve?

• The number of acidic protons is half the number of equivalence points

• The number of acidic protons is double the number of equivalence points

• The number of acidic protons equals the number of equivalence points

• They are unrelated