{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

19 Acid &amp; Base Ionization Constants

# 19 Acid &amp; Base Ionization Constants - At 50oC Kw =...

This preview shows pages 1–4. Sign up to view the full content.

1 1 At 50 o C K w = 5.48 x 10 -14 , what is the pH of pure water at this temperature? pH = - log [H 3 O + ] A) pH = 7.4 B) pH = 7.0 C) pH = 6.6 2 For pure water at 50 o C 2H 2 O H 3 O + + OH K w = [H 3 O + ] [OH - ] =5.48 x 10 -14 and the pH = 6.6 At this temperature, water is __________. A) acidic: [H 3 O + ] > [OH - ] B) neutral: [H 3 O + ] = [OH - ] C) basic: [H 3 O + ] < [OH - ] [H 3 O + ] = [OH - ] and pure water is neutral (has no net charge) at any temperature !

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 3 Today’s To Do Explain why water can be neutral and have a pH different from 7.0. Write equilibrium constant expressions for acid ionization, K a , and base ionization, K b . Define pK a and pK b , and how they are related. Determine K a and K b values from the pH or pOH and other concentration information. Determine the pH and pOH from K a or K b values and other concentration information. Identify the relative strengths of acids and bases from pK a and pK b values. 4 Why and how do equilibrium constants depend on temperature? ln( ) ln( ) 1 ln( ) o o o o RT K G G K RT H S K R T R      
3 5 Understanding the equation below mathematically. Reactants Products ln K > 0 then K > 1 and reaction as written is product favored! ln K < 0 then K < 1 and reaction is reactant favored! ln K = 0 then K = 1 and reactants and products are both present in comparable amounts 1 ln( ) o o H S K R T R   K e K ln 6 Which changes in enthapy and entropy produce a K > 1? H o < 0, an exothermic reaction S o > 0, entropy increases Enthalpy term becomes less important at higher temperatures.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.