Calculating Isoelectric Point: Definition & Formula


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question 1 of 3

The pKa for 4-nitrophenol is 7.15. At what pH would you expect there to be an equal amount of the protonated and deprotanated form?

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1. When would someone calculate an isoelectric point for a compound?

2. The amino acid alanine has two pKa values. 2.3 for the COOH group and 9.7 for the NH3+ group. What is the pI for this compound?

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About This Quiz & Worksheet

This quiz and worksheet will help you assess your understanding of isoelectric point and how to find it. Some topics addressed by practice questions include how and when to calculate the isoelectric point of a compound, the zwitterion form of a compound, and how to calculate a pI with more than two pKa values.

Quiz & Worksheet Goals

This quiz will inquire about:

  • When to calculate an isoelectric point
  • When to expect equality between protonated and deprotonated forms of a compound
  • Isoelectric point of alanine
  • Zwitterion form of alanine
  • How to calculate pI with more than two pKa values

Skills Practiced

You will exemplify your skill in the following areas:

  • Problem solving - use acquired knowledge about isoelectric points to solve for them in practice problems
  • Reading comprehension - ensure that you draw the most important information from the related lesson on calculating isoelectric points of compounds
  • Interpreting information - verify that you can read information regarding zwitterion form and interpret it correctly
  • Knowledge application - use your knowledge to answer questions about the amino acid alanine

Additional Learning

To continue learning about this physics subject, take a look at the complementary lesson named Calculating Isoelectric Point: Definition & Formula. This lesson will cover the following objectives:

  • Define isoelectric point and zwitterion
  • Explain the equation to find isoelectric point
  • Know how and when to calculate isoelectric point
  • Solve for isoelectric point of various compound in practice problems in the lesson