The!Mad!Scientist!
  • Home
  • Courses
    • IB Chemistry Home Page
    • IB Biology Home Page
    • General Chemistry
  • G10 Science Home Page
  • Calendar

The!Mad!Lab!

IB Chemistry G12

August 7 - 11, 2017

8/6/2017

0 Comments

 
Housekeeping:  Good morning.  Welcome to The!Mad!Scientist! 

Content Review:
Textbook: 
Links:  

Agenda:
1.  Welcome & introduction
2.  Navigating the website
3.  Catching up
4.  Acid/base theory
5.  Practice with conjugate acids & bases identification.
6.  Discover properties of acids and bases.
7.  The pH scale
​
Mission 1: Acid-Base Theories. 
Mission Objectives.  You should be able to:
1. Define, compare and contrast acid/base theories.
2. Explain why Arrhenius' model had to be replaced.
3. Identify conjugate acid/base pairs.

We will begin with the homie Richard Thornley.
There are three known acid-base theories: Arrhenius, Bronsted-Lowry, and Lewis.  Arrhenius's theory is very simple: Acids disassociate in water to form H+ ions and bases disassociate to form OH- ions.  Bronsted-Lowry (BL)'s definition is more inclusive. Acids are proton donors and bases are proton acceptors.  Lewis' definition focuses on the behavior of electrons.  Acids accept electron pairs and bases donate electron pairs.

We will focus mainly on Bronsted-Lowry's theory.  This leads us to the formation of conjugate acids and bases.

Acids react to form bases and bases react to form acids.  The acid-base pairs related to each other like this are called conjugate acid-base pairs and differ by a proton.  Substances that can act as an acid and a base are called amphoteric.  Water is a good example, as is the HCO3- ion.

A good example is when water becomes the hydronium ion by accepting a proton.  


H2O(l)  +  H+(aq) --> H3O+(aq)

This makes H2O/H3O+ a conjugate acid-base pair.
Picture
Let's practice!!!
Picture
Homework:  See below.
Picture
Mission 2: Equal yet Opposite.  
Mission Objectives. You should be able to:
1.  List and describe the properties of acids and bases.
2.  Identify the acids and bases needed to make different salts.
3.  Explain the necessity of indicators.

Acids and bases have different characteristics.  Acids taste sour and are sometimes sticky.  They are corrosive.  Acids turn blue litmus red, yellow methyl orange into red, and are colorless in the presence of phenolphthalein. Bases taste bitter and are usually slippery.  They are caustic.  Bases turn red litmus blue and are pink in the presence of phenolphthalein.

Acids react with bases, metals and carbonates to form salts.  The following video shows five different reactions of acids and their products.
We will focus on the reactions of acids with me​tals, acids with bases, and acids with carbonates.
Picture
Picture
Picture
It is my plan to have you guys doing your own variations of these demonstrations later in the week. Whenever possible, it's always better to do it yourself.  You may get different results and will have to explain why.  Don't be afraid.  We will be titrating next week, hopefully.

Indicators are chemical detectors.  Acids and bases change color depending on which indicator is used.  The most common indicator is litmus (turns red in the presence of acid and blue in the presence of base).  Phenolphthalein turns pink in the presence of a base, but is colorless when combined with an acid. Universal indicator is a combination of many other indicators that turns a variety of colors depending on the concentration of H+ in solution.

Image courtesy of https://tackk.com/qbel4z
Picture
Homework: See below
Picture
0 Comments



Leave a Reply.

    Archives

    February 2020
    January 2020
    November 2019
    September 2019
    August 2019
    April 2019
    January 2019
    November 2018
    September 2018
    August 2018
    July 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    April 2017
    February 2017
    January 2017
    November 2016
    October 2016
    September 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015

    RSS Feed

Proudly powered by Weebly