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Self-Ionization of Water and the pH Scale

Self-Ionization of Water and the pH Scale

Author: carolyn fruin
Description:

Learning Targets:

  • I can write the equation for the self-ionization of water.
  • I can write the equilibrium expression for water.
  • I know that the value of Kw is 1 x 10-14.
  • I can explain that every aqueous solution contain some H+ and some OH-.
  • I can use Kw to calculate for the equilibrium concentrations of [H+]  or  [OH-].
  • I know the various pHs of common household materials.
(more)
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Tutorial

Computer Tutorial - pH Scale

This video illustrates how water reacts with itself to form ions. It also determines the equilibrium constant for water, Kw. CLICK HERE to begin. Once you have watched the video, answer the questions listed below.

  1. What are some common items and their corresponding pHs?
  2. How are pH and pOH related?
  3. Describe how the strength of an acid is related to its concentration.
  4. As you complete each of the example problems, record your correct answers.

 

Source: W. W. Norton & Company

The Concept of pH

Covers basic self-ionization of water, the pH scale and pH calculations.

pH Scale Basics

The pH of a solution

•is used to indicate the acidity of a solution
•has values that usually range from 0 to 14
•is acidic when the values are less than 7
•is neutral with a pH of 7
•is basic when the values are greater than 7
 
The pH of solutions is determined by using
• a pH meter
• pH paper
• indicators that have specific colors at different pH values

Computer Tutorial - Self Ionization of Water

This video illustrates how water reacts with itself to form ions. It also determines the equilibrium constant for water, Kw.  CLICK HERE to begin. Once you have watched the video, answer the questions listed below.

  1. Write the chemical reaction between two water molecules.
  2. What is the equilibrium expression for this reaction?
  3. How was it determined that Kw = 1 x 10-14?

Source: W. W. Norton & Company

Acids, Bases and pH

What is Kw?

A description of how Kw is developed using the Keq of water and how it was determined to be 1 E -14.

Source: chemistNATE youtube channel http://www.youtube.com/watch?v=V_NrWj_KoTQ

KhanAcademy - Self Ionization of Water

An explanation of how water reacts with itself as well as how we then determine the equilibrium value of pure water.

Source: KhanAcademy

Strong Acids and Bases pH and pOH using Kw

Source: KhanAcademy