YOUNGSTOWN CITY SCHOOLS
SCIENCE: CHEMISTRY
UNIT #8: “ACIDS AND BASES” (4 WEEKS) 2013-2014
SYNOPSIS: Students will investigate the importance of acids and bases in their everyday lives. Through extensive lab work,
they will learn the processes of titration, pH calculation, and neutralization. At the end of the unit students will be given a
solution to calculate its concentration.
ENABLERS: acids, bases, dissociation, electronegative, hydronium ion, aqueous, hydroxide ion, titration, equilibrium,
Bronsted-Lowrey
and Lewis
STANDARDS
VIII. ACIDS AND BASES
A. Structural features of molecules are explored to further understand acids and bases
B. Acids often result when hydrogen is covalently bonded to an electronegative element and is easily dissociated from the rest of the
molecule to bind with water to form a hydronium ion (H3O+)
C. The acidity of an aqueous solution can be expressed as pH, where pH can be calculated from the concentration of the hydronium ion
D. Bases are likely to dissociate in water to form a hydroxide ion
E. Acids can react with bases to form a salt and water
F. Neutralization reactions can be studied quantitatively by performing titration experiments
1. Experimentally determine the concentration of an acid or base through titration
2. Use indicators to determine the identity of an unknown substance
G. Equilibrium of acids and bases and the concept of Brønsted-Lowry and Lewis acids and bases are studied
LITERACY STANDARDS
RST.1 Cite specific textual evidence to support analysis of science and technical texts, attending to important distinctions the author makes and
to any gaps or inconsistencies in the account
WHST.9 Draw evidence from informational texts to support analysis, reflection, and research
TEACHER NOTES
MOTIVATION
1. Draw on past experiences with acids and bases in other units, writing compounds, etc. to see
what students know.
2. Teacher demo on production of hydrogen gas / film canister to show reaction. Students observe
how hydrochloric acid reacts with magnesium to produce hydrogen gas. Teacher ignites gas to
create a “rocket”
3. Video of the Hindenburg Disaster; students view and then discuss what happened.
4. YouTube Video with wands filled with hydrogen gas and then ignited - - students describe
reaction of acid (metals) and hydrogen; review balancing equations with students.
5. Students set personal and academic goals
6. Preview the Authentic Assessment so students know what is expected by the end of the Unit
pH and pOH
concentration
H3O+
Kw, Ka, Kb (constants)
[OH-]
[H+] = [H3O+]
amphoteric
indicator
neutral
neutralization
pH scale
litmus
buffer
salts
hydride
VOCABULARY
anhydride
titration
end point
equivalence point
buret
pKa
pKb
Monoprotic
Diprotic
Polyprotic
Conjugate Acids
Antacids
Conjugate Bases
Organic Acid
Magnificent Seven Inorganic Acid
Swamped-out
Weak Acids
Buffer Capacity
Weak Bases
Henderson-Hasselbalch Equation
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YCS Science Chemistry Unit 8: Acids and Bases 2013-2014
TEACHER NOTES
TEACHING-LEARNING
1. Teacher presents definition and properties of Acids and Bases; students take notes. As part of
this, the teacher presents three theories: (VIIIA; VIIIB)
Arrhenius (acids produce hydrogen ions and bases produce hydroxide).
Bronsted-Lowry (proton part of compounds).
Lewis (electron or negative part of compound).
Students compare and contrast theories and read research articles about each (RST.1)
2. Characteristics of Acids and Bases: Teacher puts a T-chart on the board and students give
characteristics of Acid or Base; one student records answers for class, and students keep giving
answers until they run out of descriptors. (VIIIA) T-Chart attached on page 4.
After students have done descriptor list, discuss how people in ancient time classified something
as an Acid or Base. Have students explore at home and make of list of acids and bases found in
common substances. Students must identify at least 8-10 items from kitchen, cleaning supplies,
cosmetics, car care, bathroom, etc. Students bring in lists and identify products as acid or base
on the board. They explain why they classified something as an acid or base; class discusses
items and if there is disagreement, they test the substance in class.
3. pH Scale: acids, neutral, and bases. Teacher discusses pH and pOH, using a number line 0-14
(pH scale) and a number line 14-0 (pOH scale). Teacher gives examples such as salt water,
Coke, milk, and other common substances to see where they fit. Also, use the household item
list students brought in. Include pH of blood as 7.0 – 7.8 as the ideal; if higher or lower serious
things happen to the person. (VIIIB, VIIIC)
Students can also do testing with various types of bottled water.
4. Teacher moves from pH to Concentrations (what to touch or not to touch!). Teacher shows
students how to do the calculations with logs (try to coordinate with Math) to show how strong
the acids and bases are. Make connections to real life for students by looking at things such as:
if you had a salad, would you use vinegar or hydrochloric acid? If you wash your hands, do you
use acid or soap? Car battery and sulfuric acid. Looking at erosion of a battery - - electrolyte and
non-electrolyte. Acid in the human stomach is hydrochloric acid. If you swallowed Liquid Plumber,
how do you get it out of the system? (VIIIB, VIIIC)
5. Kw = 1.0 x 10-14 = [H+] [OH-] - - Kw = hydronium concentration x hydroxide concentration;
introduce and work problems with students. Students will be able to translate the concentrations
back to pH and pOH scales. (VIIIB, VIIIC, VIIIG)
#6
Labs are PDF Files
6. Teacher then has students do several LABS: (VIIIC, VIIID, VIIIE)
a. Acid-base-neutral lab (household products)
b. Properties of Strong and Weak Acids and Bases
c. Comparing Acid Strengths
d. Students will do a lab with an unknown substance for their Authentic Assessment
7. Acid-Base Equations - - Teacher give reactants which includes acids and bases; students predict
what the products are. Review balancing equations. The teacher should then address conjugate
acids and bases (the acid or base produced after reaction). Theory of Lewis introduced this.
Once they know the conjugate bases, students then describe - - e.g., how to neutralize sulfuric
acid; they will know how much buffer to add to get to the pH needed (HCL + NaOH →NaCl +
H2O). (VIIIE)
#8 Labs are PDF Files
8. Titrations: Teacher introduces Titrations and refers to definition and purpose (e.g., test
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YCS Science Chemistry Unit 8: Acids and Bases 2013-2014
TEACHER NOTES
TEACHING-LEARNING
concentration vitamin C in juice, Salicylic acid in aspirin, water analysis). Students perform labs:
a. Acid-base titration lab
b. Titration of fruit juice lab
c. Standard solution titration
d. Determination of acetic acid in vinegar (if time)
During labs, students graph the volume of titrant to pH. When finished, students know how to find
concentration of any solution. Students can tell end point when given any graph; they know which
indicator to use (phenolphthalein is most used indicator. (VIIIC, VIIIF, VIIIG)
TEACHER NOTES
TRADITIONAL ASSESSMENT
1. Unit Test: Multiple-Choice
TEACHER NOTES
TEACHER ASSESSMENT
1. Lab reports or practical reports, using rubrics for quality points.
2. Assignments/worksheets
3. 2- 4-point questions
TEACHER NOTES
AUTHENTIC ASSESSMENT
1. Students evaluate their goals for the Unit.
2. Titration: find concentration of unknown substance. Given 3 solutions, they choose
solution, run titration and tell concentration of acid. Compare to another acid on the board.
(IIIA2)
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YCS Science Chemistry Unit 8: Acids and Bases 2013-2014
T-L #2 CHARACTERISTICS OF ACIDS AND BASES
ACIDS
BASES
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YCS Science Chemistry Unit 8: Acids and Bases 2013-2014