General Chemistry
Unit 13
 Acids and Bases
o Naming
o Definitions
o Indicators
o pH pOH calculations
 Molarity
o Calculations
o Dilution
 Titration
(2013 – 2014)
1
How to recognize a compound/formula as being an acid or base:
Acid: has H, hydrogen, at the beginning.
Base: contains OH, hydroxide.
Naming Acids
Binary Acids
 Contain H and one other element
 To name:
hydro + second element(change ending to –ic) + acid
HCl = Hydro chlorine ic + acid
Hydrochloric acid
HF = Hydro fluorine ic + acid
Hydrofluoric acid
HI =
H2 S =
*If you are given the name and must write the formula, make sure you
check charges and do the criss-cross!
Ternary Acids (Polyatomics)
 Contain H, O and one more element
(a polyatomic ion with O in it; SO4)
 To Name:
For –ate and per -ate polyatomic ions, change the –ate ending to –ic acid.
1. HNO3 = nitric acid (was nitrate)
2. H2SO4 = sulfuric acid (was sulfate)
3. HC2H3O2 = acetic acid (was acetate)
(acetate is also CH3COO)
4. H2SO5 = persulfuric acid (was persulfate)
5. H3PO4 = phosphoric acid (was phosphate)
6. HClO3 =
7. HNO4 =
8. HIO4=
2
-ite and hypo -ite polyatomic ions become –ous acid.
1. HNO2 = nitrous acid (was nitrite)
2. HNO = hyponitrous acid (was hyponitrite)
3. H2SO3 =
4. H2SO2 =
5. HClO =
6. HIO=
Naming Bases:
Name the metal first + hydroxide
NaOH = sodium hydroxide
Ca(OH)2 = calcium hydroxide
Fe(OH)3 = iron (III) hydroxide
3
Naming Acids and Bases
Name the following:
1. HI _____________________
2. HClO3 _____________________
3. Pb(OH)4_____________________
4. H3PO4 _____________________
5. LiOH _____________________
6. H2SO3 _____________________
7. HNO4 _____________________
8. H2CO_____________________
9. Fe(OH)3 _____________________
10. HCl _____________________
11. Ca(OH)2 _____________________
12. HBrO _____________________
Write the formula for the following:
13. Percarbonic acid _____________________
19. Mercury (II) hydroxide ___________________
14. Hydrofluoric acid _____________________
20. Acetic acid _____________________
15. Chlorous acid _____________________
21. Barium hydroxide _____________________
16. Hyposulfurous acid _____________________
22. Nitrous acid _____________________
17. Persulfuric acid _____________________
23. Hypophosphorous acid _____________________
18. Zinc hydroxide _____________________
24. Sulfuric acid _____________________
4
Acids and Bases
Properties of Acids
1.
Taste Sour
2.
Itchy on skin
3.
Blue Litmus turns RED
Red Litmus Stays RED
4.
React with Bases
Neutralization:
Acid + Base  Salt + Water
Examples – Vinegar
Citrus Fruit
Properties of Bases
1.
Tastes Bitter
2.
Feels slippery
3.
Red Litmus turns BLUE
Blue Litmus stays BLUE
4.
React with Acids
Neutralization:
Acid + Base  Salt + Water
Examples – Soaps
Milk of Magnesia
Ammonia
5
pH Measurement
1. Litmus paper
 Red for Acid
 Blue for Base
 Cheap but very qualitative; only can tell if acid or base
2. Chemical Indicators
 Color change in a small pH range
 Many chemical indicators to choose from
o Universal Indicator
 pH 4 to pH 10
 Various colors
o Phenolphthalein
 Clear to Magenta at pH = 9
o Natural Indicator
 Cabbage – anthocyanin pigment
 Get more information as it can be matched to a color to get an approximate pH.
Universal Indicator
3. pH Meter
 most accurate method
 Get a numerical value
 Most expensive but get quantitative data.
6
Acids and Bases
3 Theories
Theory 1 = Traditional (Arrhenius)

Acid - Formula has “H” written first and ionizes in water to form HYDRONIUM ION
o Hydronium Ion = H3O+
o HF + H2O  F- + H3O+

Base – Formula has OH at end and ionizes in water to form HYDROXIDE ION
o Hydroxide Ion = OHo LiOH  Li+ + OH-

Salt – Compound whose chemical formula does not contain H first or OH last
o BaSO4
Practice: ( Acid, Base or Salt)
1.
H2SO4
2.
LiCl
2.
HNO3
3.
KOH
4.
NaNO3
5.
Ba(OH)2
7
Theory 2 = Bronsted-Lowry Theory

Acid – a “proton donor” – donates H+

Base = “proton acceptor” – accepts H+
o Acid and Base are located on left side of arrow

Conjugate acid – forms when Base accepts H+

Conjugate Base – piece of acid left after H+ is donated
o C. Acid and C. Base are located on right side of arrow
Acid + Base  C. Acid + C.Base
1. CH3OH + NH2-1  CH3O+1 + NH3
2. HCN + SO4-2  HSO4-1 + CN-1
3. CN-1 + HBr → HCN + Br-1
4. HCl + PO4-3
→
5. HNO3 + H2PO4-1
HPO4-2 + Cl-1
→
NO3-1 + H3PO4
8
Bronsted Lowry Acids and Bases Worksheet
Acids give up protons (H+)
Bases accept protons (H+)
Acid + Base → Conjugate Acid + Conjugate Base
Acid
Conjugate Base
H2O
H3O+1
CO3-2
HNO3
NH3
Base
Conjugate Acid
H2O
CO3-2
HCO3-1
HSO4-1
H2PO4-1
9
Theory 3 = Lewis Theory

Acid – electron pair acceptor

Base – electron pair donor
o
BH3
o SeI4
o PBr3
o SF6
10
The pH Scale
 Measure or count of the hydrogen (hydronium)
ion concentration
 Scale ranges from 0 – 14
o 7 < = acidic (0 is most acidic)
o 7 = neutral
o 7< = basic (14 is most basic)
 pH = -log[H+] or –log[H3O+]
 pOH = -log[OH-]
 pH + pOH = 14
 [H+] and [H3O+] = 10–pH
 [OH-] = 10-pOH
11
Problem #1: pH of .01M HNO3 solution
pH =
Problem #2: pH of .00001 M HC2H3O2
pH =
Problem #3:
pH of solution with a hydrogen concentration of 2.3 x 10-6 M ?
pH =
Problem #4: pOH of .0001 M NaOH
pOH =
Problem #5: pH of .0001 M NaOH
Problem #6: pH and pOH of .000001 M KOH
Problem #7: Find [H+] if pOH = 3
12
Name __________________________________________________________
pH and pOH calculations
Fill in the missing information in the table below.
pH
1
[ H3O+ ]
pOH
3.89 x 10–4 M
3
5.19
4.88 x 10–6 M
4
8.46
6
2.14
8.45 x 10–13 M
7
2.31 x 10–11 M
8
9
9.94
7.49 x 10–6 M
10
2.57 x 10–8 M
11
12
ACID or
BASE?
3.78
2
5
[ OH– ]
10.91
13
Acid Base Calculation Practice
1. What is the hydroxide ion concentration of a solution whose pH is 12.40?
2. What is the pH of a 0.00162 M NaOH solution?
3. If [H3O+1] = 8.26 x 10-5 M, what is the pH of the solution?
4. What is the molarity of a NaOH solution if 4.37 mL of the NaOH solution is
titrated by 11.1 mL of 0.0904 M HNO3?
5. What is the hydroxide ion concentration of a solution whose pH is 12.40?
6. What is the pH of a 0.00162 M KOH solution?
7. If [H3O+] = 8.26 x 10-5 M, what is the pH of that solution?
8. If the hydroxide concentration is 3.00 x 10-10 M, what is the hydronium
concentration?
14
Indicators and pH
I. Problem: Many different compounds tend to change color in different types of solutions. Is there a
relationship between these colors and the pH of the solutions? Can I use these color changes to
predict the pH of an unknown solution?
II. Background Information: pH is a unit that has been designed to determine the strength of an
acid. This unit is a count of the hydronium ions so that a determination of the acid strength of a
solution can be made. Several substances change color with different pH. These color differences
can then be used to determine the approximate pH of a substance.
III. Procedure:
1) Place a clean and dried microplate on a piece of white paper.
2) Add ~25 drops (about half of the well) of each varying pH solution according to data table 1. (Ex.
add vinegar to the four wells in the column labeled vinegar). Also, use an unknown solution in the
sixth column and record its letter in table 1.
a. Add 2 drops of Bromothymol Blue to each well in the first row.
b. Add 2 drops of Universal Indicator to each well in the second row.
c. Add 2 drops of Phenolphthalein to each well in the third row.
3) Gently swirl the well plate to mix the solutions completely.
4) Record the resulting colors in the data table.
5) Use the solution in the fourth row (no indicator) to test the pH using the red and blue litmus
paper:
a. Place one piece each of the red and blue litmus paper on a paper towel.
b. Use a clean glass stirring-rod to obtain a tiny droplet of the solution to be tested and
apply it to a clean area of the litmus paper.
c. Wipe dry the stirring-rod before testing another solution.
d. Record your observations in the data table.
6) Use this info to determine the pH value (to the tenth place) of the unknown. pH=
7) Raise your hand so the instructor can use a digital pH meter to test your accuracy.
_____
pH meter reading=______
Data table 1. Vinegar
pH=3.0
Seltzer
Water
pH=5.5
Neutral
pH=7.0
0.1 M
NaHCO3
pH=10.0
Ammonia
pH=12.0
Unknown
Letter ___
Bromothymol
Blue
Universal
Indicator
Phenolphthalein
Red Litmus
Blue Litmus
Cabbage
Juice
15
IV. Data Analysis:
1) At what pH(s) does bromothymol blue, universal indicator, and phenolphthalein
change color?
pH of color change
bromothymol blue
universal indicator
phenolphthalein
2) a. What color does red litmus turn in the presence of an acid and a base?
b. What color does blue litmus turn in the presence of an acid and a base?
3) Which indicator(s) gives no information in the acid-to-neutral pH range?
4) Calculate the hydronium concentration of the unknown solution using the estimated
-pH
pH value and the pH meter reading. (Remember pH = - log [H3O+], or 10
= [H3O+]))
[H3O+] from estimated pH value______________________________________
[H3O+] from pH meter reading ______________________________________
16
Review for Acids and Bases
1. Based on Arrhenius’s definition of acid, base and salt, predict which of the following
compounds are acids, bases or salts.
Ca3(PO4)2
HBr
Cr(OH)2
HgCl2
H2Se
2. Based on the Bronsted-Lowry Theory of acids and bases, predict where a hydrogen is
being lost, where it is being gained, and label the reactants and products:
a. HCl + NH3  NH4+ + Cl-
b. SO42- + H2O  HSO4- + OH-
3. Given the following acids, predict the conjugate bases:
Acid
HF
H2S
HNO
Conjugate Base
H2O
4. Given the following bases, predict the conjugate acids:
Base
HSO3-1
IPO4-3
Conjugate Acid
H2O
5. For these compounds, predict if they are a Lewis acid or Lewis base….I need to see the
“dots”!
a.
PF5
b. NBr3
17
6. Are the following acids, binary or ternary?
Acid
H2SO4
HBr
HCN
H2CO3
HI
H2Se
Binary or Ternary
7. Fill in the Table:
Chemical Formula
Name
Iron (III) hydroxide
Phosphoric Acid
H2Se
HBrO
Nitrous acid
HCl
Hypo bromous acid
Ba(OH)2
Iodic acid
Hydroiodic acid
HIO2
8. How many color changes do most chemical indicators go through between a pH of 0 and
a pH of 14? _____________
9. What is the indicator that we used that is very unique in that it changes color 7 times
between a pH of 4 and a pH of 10?
10. True or False: Cabbage Juice only goes through 1 color change between 0 and 14?
________________
11. When using litmus paper, acid is represented by what color? _____________
12. When using litmus paper, base is represented by what color? _____________
13. List 3 properties of acids and 3 properties of bases.
18
14. Complete the table:
[H+]
1
2
3
4
5
6
7
8
pH
8.99
pOH
[OH-]
Acid, base or neutral
5.06
7.28 x 10-3 M
2.99 x 10-14 M
6.23 x 10-7 M
10.56
4.61x 10-5 M
12.62
15. What is the pH of a 0.0235 M HCl solution?
16. What is the pOH of a 0.0235 M HCl solution?
17. What is the pH of a 6.5 x 10-3 M KOH solution?
19
1. Solution
Solution Terms
2. Solvent
3. Solute
4. Aqueous solution
5. Saturated
6. Unsaturated
7. Concentrated
8. Dilute
9. Mass percent
10. Molarity (M)
11. Standard solution
12. Dilution
13. Normality (N)
14. Molality (m) = concentration of solution in moles of solute per
kilograms of solvent.
20
Molarity

Measure of the “strength” of a solution

“Strong” has higher molarity

“Weak” has lower molarity

Solution has 2 parts
o Solute – what gets mixed in
o Solvent – what does the dissolving (typically water)

Quantitative – need accuracy

Typically use volumetric flasks

Include Molarity on bottles
o 3M HCl (3M Hydrochloric Acid)

# of moles of solute
Molarity = -------------------------Liters of solution

Units are moles / Liter or M or M

A 3M solution is read as a 3 molar solution
There is a distinction between mole and molar

Moles represent a quantity

Molarity represents a concentration
So 0.1M is a concentration of .1 moles / 1 liter of solution, it does not mean .1 moles.
21
Example:
Make a 1M solution using KBr
Definition says
1 mole of KBr
------------------1 Liter or 1000 ml H2O
What units do we “weigh” in?
grams
How do we convert moles to grams??
Moles x Molar Mass
Convert 1 mole of KBr to grams:
K = 39.10
Br = 79.90
119.00 grams / mole
Weigh 119.00 grams of KBr
Put it into a 1 Liter volumetric flask
Fill to line
Shake until dissolved
22
Making Solutions:
1. Determine the grams of solute needed to make 1.00 L of a 1.0 M solution of NaCl
2. Determine the grams of solute needed to make 1.00 L of a 0.50 M solution of NaNO3.
3. Determine the grams of solute needed to make 100.00 mL of a 1.00 M solution of
Al(OH)3.
4. Determine the grams of solute needed to make 100.00 mL of a 0.20 M solution of KI.
23
Molarity Problems
1. Determine the number of grams of H2SO4 needed to prepare 1.00 liter of a 2.50M
solution of H2SO4.
2. Determine the number of grams of aluminum sulfate needed to prepare 1.00 liter of
a 0.025M aluminum sulfate solution.
3. Determine the number of grams of phosphoric acid needed to prepare 250.00 mL of
a 1.00M phosphoric acid solution.
4. Determine the number of grams of calcium hydroxide needed to prepare 100.00 mL
of a 0.100M calcium hydroxide solution.
5. 4.00 moles of nitric acid molecules are dissolved in 1.50 L of water. What is the
molarity of this solution.
24
Molarity Problems
(SHOW ALL WORK)
1. How many grams of CaCl2 would be required to produce a 3.50 M solution with a volume
of 2.00 liters?
2. What is the molarity of a .50 Liter solution containing 249.00 grams of KI?
3. How many moles of LiF would be required to make a 2.50 M solution with a volume of
1.50 Liters?
4. A sample of NaNO3 weighing 8.50 grams is placed in a 500.00 ml flask. Distilled water is
added to the mark on the neck. What is the molarity of this solution?
5. How many grams of NaI would be needed to produce a 2.00 M solution with a volume of
1.00 Liters?
6. How many moles of Sr(NO3)2 would be used in the preparation of 10.0 Liters of a 6.0 M
solution?
25
More Practice
1. What is the equation for Molarity?
2. What is the molarity of a solution if 5.30 g of Na2CO3 is dissolved in 400.0 mL of
water?
3. How many moles of NaCl are contained in 100.0 mL of a .200M solution?
4. What weight (in grams) of H2SO4 would be needed to make 750.00 mL of a 2.00M
solution?
5. What volume (in mL) of water would be needed if you had 2.45 grams of H2SO4 to
make a 18.0 M solution?
6. What is the molarity of a solution made by dissolving 20.0 g of H3PO4 in 50.00 mL of
water?
26
Dilution
1. What is the equation for dilution?
2. What volume of 0.250 M KCl is needed to make 100.0 mL of 0.100M KCl solution?
3. Concentrated H2SO4 is 18.0 M. What volume of 18.0 M solution is needed to make
2.00 L of 1.00 M H2SO4 solution?
4. Concentrated HCl is 12.0 M. If 250.0 mL of this 12.0 M solution are diluted to
750.0 mL, what is the molarity of this diluted solution?
5. 2.00 L of 0.800M KNO3 are prepared using 162.0 mL of a more concentrated KNO3
solution. What is the molarity of this solution?
6. A 0.500 M solution is to be diluted to a 0.125 solution. If the original volume is 844
mL, what is the volume after the dilution?
27
More Dilution!
1. If I add 25.0 mL of water of a 0.150 M NaOH solution, what will the molarity of the
diluted solution solution be?
2. If I add water to 100.00 mL of a 0.150 M NaOH solution until the final volume is
150.00 mL, what will the molarity of the diluted solution be?
3. How much 0.050 M HCl solution can be made by diluting 250.00 mL of 10.0 M HCl?
4. I have 345.00 mL of a 1.50 M NaCl solution. If I boil the water until the volume of
the solution is 250.00 mL, what will the molarity of the solution be?
5. How much water would I need to add to 500.00 mL of a 2.40 M KCl solution to make
a 1.00 M solution?
28
Titration for Acids and Bases
Titration is a method used to determine the concentration of an unknown acid
(hydronium ion H3O+ or H+) or base (hydroxide OH-).
Starting with a solution of unknown concentration of acid or base, small
volumes of a solution of known concentration (titrant) are added until an
equivalence point or a neutralization point is reached. Typically, the titrant is
a strong acid or base.
To help determine when the equivalence point occurs, indicators are used. The
indicator used will depend on the system being studied since they all change
color at slightly different pHs. The indicator should have its color change
near the equivalence point of the reaction.
Some examples:
Indicator
Litmus paper
Methyl Orange
Phenolphthalein
Color in Acid
Red
Pink
Colorless
Color in Base
Blue
Yellow
Magenta
When the indicator changes color, the hydronium or hydroxide ions in the
unknown solution have been neutralized.
The method of expressing concentration of the solution is Normality (N).
Normality is expressed as equivalence of solute per liter of solution.
Equivalence is related to the number of H3O+ or OH- that are available for
neutralization.
H2SO4 has 2 equivalence of H+
Al(OH)3 has 3 equivalence of OH-
29
Titration Technique
Typically, the unknown solution and the indicator are in the flask and the
known solution is put into the buret.
There are several steps used to prepare the buret for the titration.
1. Rinse the buret several times with the titrant (approximately 5 mL each time) to be
used in the analysis. Use the stopcock to ensure the whole buret has been rinsed,
including the tip. Discard all of this titrant into a waste beaker.
2. Drain several milliliters of titrant through the tip using the stopcock to remove any
air bubbles that might be present. Again, dispose this titrant into the waste beaker.
3. Fill up the buret, but the level of the titrant must be on the buret scale. Record this
initial reading (see top of next page)
4. Repeat steps 1 – 3 for the unknown solution.
30
In order to get accurate data, one must know how to read the level of the solution in the
buret. The level of the liquid in the buret is not a straightl line. It is actually a curved line
called a meniscus. The meniscus should be viewed at eye level. The correct way to read a
meniscus is to observe where its lowest point is and take a reading. One should always
estimate the last digit of the value taken.
It can be helpful to hold a white card behind the buret to make the meniscus easier to
read.
First, we need to put a measured amount of the unknown solution into a flask. This value
will be given to us. After adding the given amount, another accurate reading should be
taken. This is the volume for the unknown solution (VB). The Normality (NB) will be solved
for at the end of the experiment.
Next 2 or 3 drops of indicator are added to the flask.
The flask is then placed under the buret that contains the titrant or known solution.
Slowly, the known solution is added to the liquid in the flask – remember we are looking for
the equivalence point where we will see a color change based on our indicator. The flask
must be swirled at all times while the titrant is being added.
**It can also be helpful to place a white piece of paper underneath the flask to help
identify when the color change happens. You are only looking for a slight color change for
31
the equivalence point. A bold color change indicates that you went too far with the
titration. Lighter is better!!! The color has to stay for 30 seconds.
You shouldn’t add the titrant too fast because it is easy to add too much, but if you add it
too slowly, the titration could take a long, long time. So, you can add the titrant steadily
until the color starts to hand around for a while but still disappears. At this point, it
should be added drop wise until the desired color change occurs.
Take an accurate buret reading of the titrant when a slight but constant color change
appears. This buret value is VA and NA should have been given since it was the titrant.
Using the following equation to solve for the Normality (NB) of the unknown solution:
NA x VA
= NB x VB
Where NA is the Normality of the titrant, VA is the volume of the titrant used,
NB is the Normality of the unknown and VB is the volume of the unknown used.
Solving for NB : (NA X VA)
VB
Here are a couple of examples to practice using the above equation:
Example 1: It takes 15 mL vinegar to neutralize 25 mL of .5N Cd(OH)2. What is the
normality of the vinegar?
Example 2: How many mL of .02N KOH will neutralize 15 mL of .4N H2SO4?
32
Name _____________________________________________________
Questions on the titration reading
1. What is titration?
2. What is the titrant and what type of compounds are used as titrants…usually?
3. What types of materials are used for the equivalence point and why are they used?
4. Normality (N) =
5. Draw a sketch of a titration set up
6. Why should we rinse the buret before using it for a titration?
7. Do you need to record the initial level of titrant?
8. What is a meniscus and how should it be read?
9. How much indicator is added and where is it added?
10. Why do we put white paper under the flosk?
11. Why do we swirl the flask while adding titrant?
12. What does a bold color change indicate?
33
13. Describe the procedure for adding the titrant.
14. What do the variables in the equation NA x VA
= NB x VB represent?
NA
VA
NB
VB
15. Rearrange the equation so you can solve for NB
NB
34
Titration Calculations
Acid side = Base side
[H+] = [OH-]
Normality
Acid
x Volume Acid = Normality
Base
x Volume Base
Normality = Molarity x Equivalence
Molarity = moles of acid
liters of solution
Equivalence = # of Hs
moles of acid
Molarity of acid x Equiv of acid x volume
moles of acid
x
Liters of solution
# of Hs x Liters
moles of acid
Normality of acid
x
or
# of OHs
moles of base
Molarity of base x Equiv of base x volume
=
moles of base x
Liters of solution
Volume
# OHs
x Liters
moles of base
Normality of base
x
Volume
All calculations should be done using a balanced equation
**If the acid only has 1 H+ then Molarity and Normality are the same.**
Name _______________________________________
35
Monoprotoic Titration calculations
1. What volume of 0.300 M HNO3 will be required to react with 24.00 mL
of 0.250 M KOH?
2. What volume of 0.250 M NaOH will be required to neutralize 116.0 mL
of 0.0625 M HClO4?
3. If 0.481 grams of the monoprotic acetic acid, was neutralized with
20.00 mL of 0.400 M NaOH, calculate the molar mass of the acid.
4. What mass, in grams, of KOH will be required to react with 100.0 mL of
0.800 M HCl?
36
Using titration….
Solving for the Molarity of an Acid
In an Erlenmyer flask:
Liquid of known
concentration
1. Using a pipetor, add 15.00 mLs of HCl with an unknown
molarity.
2. Add 20.00 mL of dionized water using a graduated
cylinder
3. Add 3 drops of phenolphthalein indicator
Liquid of unknown
concentration
In a Buret:
1. Using 5 mL of NaOH rinse the buret
2. Fill to the 0.00 line with 0.05M NaOH
3. With the erlenmeyer flask under the buret, open the stopcock slowly and with constant swirling add
NaOH to the acid solution. Slow down the addition of the NaOH as the color change takes longer to
disappear.
4. Stop when you see a LIGHT magenta color. The color must stay for at least 30 seconds. If it doesn’t,
keep adding titrant dropwise until it does.
5. Titrations should always be done at least twice….repeat steps 2 – 4
At the neutralization point, where the color changes
the concentration of Base = the concentration of Acid:
[Base]
Molarity base x Equivalence base x Volume base
=
[Acid]
= Molarity acid x Equivalenceacid X Volume acid
Solve for Molarityacid
37
Name___________________________________________
% Acetic Acid in Vinegar
Problem: Using titration, is it possible to determine the % acetic acid in vinegar
accurately (+/- 5%)?
Background: (3 good sentences about titration)
Procedure:
1. Fill the buret with .50N NaOH. Record the initial reading on the
buret in the table below.
2. Withdraw 15.00 ml of vinegar (use 5 ml pipette 3 times). Put into a 125 Erlenmeyer
flask. Add 20 ml deionized H2O to the flask using a graduated cylinder.
3. Add 3 drops of phenolphthalein to the flask.
4. Put a piece of white paper under the flask. Titrate with NaOH; swirl the flask
frequently. Add the NaOH drop by drop near the end point. The solution should be a
light pink color at the end point.
5. Discard the solution in the flask down the drain, rinse the flask thoroughly and run a
second titration.
Observations:
Trial One
Concentration of
NaOH (NB)
Volume of Acid
Used (vinegar) (VA)
Volume of Base
Used (NaOH) (VB)
End Value
Start Value
Total
Trial Two
Average
End Value
Start Value
Total
Calculations:
1. Solve the following equation for NA : VA x NA = VB x NB
NA =
2. Determine % Acetic Acid
% HC2H3O2 =
OVER
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Conclusions:
Calculate % error on your % Acetic Acid value:
Accepted Value - Experimental Value
% error = ----------------------------------------------------Accepted Value
x 100
Where
accepted value = the value of acetic acid off of the label on the bottle
experimental value = the number determined under calculations.
List places where error could occur in this experiment:
1.
2.
3.
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More titration practice
1. If .250 grams of a monoprotic acid are neutralized with 25.00 mL of
.500 M NaOH solution. What is the molar mass of the monoprotic acid?
Which one of these given monoprotic acids was used in this
titration? Circle the answer.
HF = 20.01 g/mole
HCl = 36.46 g/mole
HBr = 80.91 g/mole
HI = 127.91 g/mole
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