Introduction to Acids & Bases Thursday, May 4th, 2017

How Do you Characterize Acids and Bases? pH scale – a measure used to report the acidity of a solution Range 0 to 14

Indicators - chemical substances that change color based on pH

Indicators - chemical substances that change color based on pH

Use the handout to complete the Venn Diagram in your notes. Acid/Base Venn Diagram Use the handout to complete the Venn Diagram in your notes.

Three Acid/Base Theories complete the chart and put in your notebook Arrhenius - H+ and OH- production in water Acid – produces H+ in water HCl + H2O → H3O + + Cl- or dissociation equation: HCl (aq) → H + (aq) + Cl- (aq) Base – produces OH- in water dissociation equation: NaOH (aq) → Na + (aq) + OH- (aq)

Bronsted – Lowry – proton transfer between reactants Acid – donates a proton Base – accepts a proton      HF  + NH3  →   NH4 +  +  F-     acid           base

Lewis – electron pair transfer between reactants Acid – accepts electron pair Base – shares electron pair   H+  + :NH3  →   NH4 +           acid           base

Common Acids and Bases to Memorize   HCl – hydrochloric acid [hydrogen chloride] H2SO4 – sulfuric acid [hydrogen sulfate] HNO3 – nitric acid [hydrogen nitrate] H2CO3 – carbonic acid [hydrogen carbonate] NaOH – sodium hydroxide Ca(OH)2 – calcium hydroxide NH3 – ammonia

Why are these called acids and bases? Why do they cause a color change? They deviate from the natural water ion concentration             Salt in water:    NaCl (aq)   Na+ (aq)   +  Cl- (aq) Water forms ions – self ionization! H2O  H + + OH-   Hydrogen ion [H +]      vs        hydronium ion [H3O +]       (proton) Transferred in Exists in aq solutions A/B rxn         

Which of the following substances are acidic, basic or neutral? H2O   H +  +  OH- Water is neutral because for Water [H+]=[OH-]  both = 1.0 x 10-7M Acid  or acidic solution – [H+] > [OH-]  [H+] > 1.0 x 10-7M Base or alkaline solution (basic) - [H+] < [OH-]  [H+] < 1.0 x 10-7M Which of the following substances are acidic, basic or neutral? a) A solution with  [H+] = 1.0 x 10-3M b) A solution with  [H+] = 1.9 x 10-8M c) A solution of salt and water

pH = -log [H+1] pOH = -log [OH-1] [H+1][OH-1] = 1 x 10-14 pH Formulas: [H+1] = 10-pH [OH-1] = 10-pOH pH = -log [H+1] pOH = -log [OH-1] [H+1][OH-1] = 1 x 10-14 pH + pOH = 14

Calculate the pH of the following: pH can be determined mathematically from the concentration! [H+] = hydrogen ion molar concentration Working with log and antilog is easy all you do is find the key on your calculator!: pH = -log [H+] [H+ ] = 10-pH Calculate the pH of the following: a) What is the pH of a solution with [H+] = 1.0 x 10-3M b) What is the pH of a solution with [H+] = 1.9 x 10-8M c) What is the [H+] of a solution with a pH of 5 d) What is the [H+] of a solution with a pH of 3.7

a) What is the pOH of a solution with [OH-] = 1.0 x 10-3M OK so pH is related to how acidic something is....but what about the other ion??? [OH-] = hydroxide ion molar concentration This focus on how basic something is pOH = -log [OH-] [OH- ] = 10-pOH a) What is the pOH of a solution with [OH-] = 1.0 x 10-3M b) What is the [OH-] of a solution with a pOH of 10.7

a) What is the pOH of a solution with pH = 5.75? Oh and YES there is a relationship between the two!!!! pH + pOH = 14   [H+] [OH-] = 1.0 x 10-14                a) What is the pOH of a solution with pH = 5.75? b) What is the [OH-] of a solution with a pH of 4.5?

Complete the Intro to Acid/Base Review Worksheet