CHEM 343 Lab Final Exam | Questions with Verified Answers
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CHEM 343 Lab Final Exam | Questions with Verified Answers Acetic acid is a weak acid. When acetic acid dissolves in water to make a solution, what is the major form of acid in the solution? a. Water b. Hydronium ion c. Acetate ion d. Hydroxide ion e. Acetic acid Rank the following compounds in o...
Acetic acid is a weak acid. When acetic acid dissolves in water to make a solution, what
is the major form of acid in the solution?
a. Water
b. Hydronium ion
c. Acetate ion
d. Hydroxide ion
e. Acetic acid
Rank the following compounds in order of their increasing pKa (lowest pKa to highest):
water, methane, benzoic acid, HCl
a. HCl, water, benzoic acid, methane
b. HCl, benzoic acid, water, methane
c. water, methane, HCl, benzoic acid
d. benzoic acid, HCl, water, methane
e. methane, water, benzoic acid, HCl
As in part B of exp. 1, when the graphs are made properly, the density of the liquid can
be obtained via:
a. Slope
b. R-square
c. y-intercept
Which of the following is mostly insoluble in water?
a. Hydrochloric acid
b. Sodium chloride
c. Benzoic acid
d. Sodium benzoate
From the lecture, which one of the following is not one of the five basic categories of
organic lab work?
a. Heating
b. Analysis
c. Separation
d. Organic reaction
,In the acid-base reaction from experiment 1, what is the conjugate acid?
a. Hydrochloric acid
b. Benzoic acid
c. Sodium chloride
d. Sodium benzoate
If a student added HCl(aq) to sodium benzoate and stopped around pH 3 (instead of 2
as described in the lab procedure), how would this affect the % yield of this experiment?
a. This change will impact % purity more than % yield
b. Lower % yield
c. Higher % yield
Name two pieces of equipment essential for carrying out vacuum filtration:
a. Buchner funnel
b. Side-arm flask
c. Short-stem funnel
d. Erlenmeyer flask
e. Beaker
Imagine an organic liquid A has a density of 0.825 g/mL and is mixed with water.
Assume this organic liquid does not dissolve in water, then the top layer must be:
a. Organic
b. Aqueous
If you need 9.49 mmol sodium benzoate as a starting material, what mass, in grams,
would you add to the reaction.(MW of sodium benzoate is 144.1 g/mol, the density is
1.44 g/mL)?
1.37g
Which of the following is used to separate aqueous and organic liquids?
a. Buchner funnel
b. Separatory flask
c. Separation tube
d. Separatory funnel
If methylene chloride has a density of 1.34 g/mL and was used in an extraction with an
aqueous solution, which would be the bottom layer in the separatory funnel?
a. Organic
b. Aqueous
, Acetaminophen is the chemical name of what common drug?
a. Ibuprofen
b. Morphine
c. Aleve
d. Tylenol
Why would a compound with more h-bonds be more soluble in water?
h-bond interactions allow for bonds to be broken, allowing for better dissociation
(solubility)
Which of the following outcomes would most possibly occur if you acidified sodium
acetylsalicylate to pH 4 instead of pH 2?
a. Falsely low % recovery of aspirin
b. Falsely low % recovery of unknown
c. Falsely low % recovery of sucrose
d. Falsely high % recovery of aspirin
What ingredient of Panacetin is the most acidic and most easily ionizable in the
presence of a base?
a. Panacetin
b. Sodium acetylsalicylate
c. Sucrose
d. Acetylsalicylic acid
If you want to make 41 mL of 0.2 M NaOH solution, what mass (in grams) of NaOH
would you need to dissolve? (Use the molecular weight of NaOH as 40 g/mol)
0.33g
What makes alcohols less soluble in room temperature water?
long carbon chains
Which of the following outcomes would most possibly occur if you initially dissolved the
panacetin mixture in a more polar organic solvent, still immiscible in water, instead of
dichloromethane?
a. Falsely high % recovery of sucrose
b. Falsely low % recovery of aspirin
c. Falsely low % recovery of sucrose
d. Falsely low % recovery of unknown
What results when too much solvent is used to dissolve the product in recrystallization?
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