What is the solute in a solution made by mixing 10 mL of methanol and 50 mL of w
ID: 1017278 • Letter: W
Question
What is the solute in a solution made by mixing 10 mL of methanol and 50 mL of water?
acetone
water
methanol
ethanol
5 points
QUESTION 2
How much more acidic is a solution of pH 2 than a solution of pH 5?
1000 times more acidic
100 times more acidic
10 times more acidic
1 times more acidic
5 points
QUESTION 3
Silver chloride is __________ in water.
molecular
soluble
neutralized
insoluble
5 points
QUESTION 4
What is the % (w/w) concentration of a sodium chloride solution prepared by adding 8.0 grams NaCl to 125. g of water?
6.0 %
5 points
QUESTION 5
What is the molarity of a solution made by dissolving 136.0 grams of C6H12O6 in enough water to make 2055 mL of solution?
0.8 mol/L
0.048 mol/L
0.368 mol/L
0265 mol/L
5 point
QUESTION 6
25. mL of 15.0 M NHOH is diluted to a total volume of 1.25 L. What is the molarity of the diluted solution?
0.158 M
1.29 M
0.30 M
0.11 M
5 points
QUESTION 7
Which molecule is an omega-3 fatty acid?
.
.
.
.
5 points
QUESTION 8
Which has a higher melting point?
.
.
.
.
5 points
QUESTION 9
What is the condensed structure of the wax that is produced in the following acid catalyzed reaction?
CH3(CH2)16CH2COOH + CH3(CH2)7CH2OH --->
CH3(CH2)16COOCH2CH2(CH2)8CH3
CH3(CH2)16COOCH2(CH2)8CH3
CH3(CH2)8COOCH2CH2(CH2)16CH3
CH3(CH2)16CH2COOCH2(CH2)7CH3
5 points
QUESTION 10
What is the product of this reaction? Glycerol + 3 CH3(CH2)4COOH ---> ?
CH3CH2CH2CH2CH2COOCH3
.
.
3 CH3(CH2 )4CH2COOCH3
5 points
QUESTION 11
If the concentration of H+ in water is 3.5 x 10-8, what is the pH?
7.5
3.2
6.5
9.1
5 points
QUESTION 12
If the pH of an aqueous solution is 8.2, what is the concentration of H+ ?
1.58x10-6
6.31x10-9
4.16x10-8
8.2x10-5
5 points
QUESTION 13
A solution with a OH- concentration of 9.2x10-4 is ________.
Neutral
Basic
Acidic
pH 3
5 points
QUESTION 14
What is the predominate species for the H2PO4-/HPO42- buffer at a pH of 5.8? Ka = 6.2x10-8
H3PO4
H2PO2-
H2PO4-
HPO42-
5 points
QUESTION 15
A solution with H+ concentration of 3.4x10-9 will turn a plant pigment molecule (red litmus) from red to __________.
blue
yellow
black
green
5 points
QUESTION 16
The CH3CH2CH2CH2CH2- part in CH3CH2CH2CH2CH2COOH is a ___________ group.
butyl
propyl
ethyl
pentyl
5 points
QUESTION 17
What is the condensed structure for hexanoic acid?
CH3CH2CHCHCH2CH2COOH
CH3CH2CH2CH2CH2CH2CH2COOH
CH3CH2(CH2)3 CH2CH2CH2COOH
CH3CH2CH2CH2CH2COOH
5 points
QUESTION 18
2-ethyl-4-methylpentanoic acid
3,3-dimethylbutanoic acid
2-methylpentanoic acid
2-methyl-4ethylpentanoic acid
5 points
QUESTION 19
What is the line-bond structure for 4-methylpentanoic acid?
.
.
.
.
5 points
QUESTION 20
What is the name of the base form (carboxylate ion) for hepanoic acid?
methylhexanide ion
ethyl-4-hexanoic ion
4-methylhexanoate ion
heptanoate ion
A.acetone
B.water
C.methanol
D.ethanol
Explanation / Answer
1)
solute is the least amount in the solution
in this case
the least amount is methanol
so
methanol is teh solute
the answer is C) methanol
2)
we know that
pH = -log [H+]
[H+] = 10^(-pH)
when pH = 2 , [H+] = 10-2
when pH = 5 , [H+] = 10-5
so
pH = 2 solution is 1000 times more acidci than pH = 5
so
the answer is A) 1000 times more acidic
3)
AgCl is insoluble in water , it forms a precipitate
so
the answer is D) insoluble
4)
mass of solution = mass oof NaCl + mass of water
mass of solution = 8 + 125 = 133
now
% (w/w) = mass of NaCl x 100 / mass of solution
= 8 x 100 / 133
= 6
so
the answer is B) 6 %
5)
moles = mass / molar mass
molar mass of C6H1206 = 180 g/mol
so
moles of C6H1206 = 136 / 180 =0.75555
now
molarity = moles of C6H1206 / volume of solution (L)
molarity = 0.7555 / 2.055
molarity = 0.3676 M
so
the answer is C) 0.368 mol/L
6) we know that
for dilution
M1V1 = M2V2
so
15 x 25 = M2 x 1250
M2 = 0.3 M
so
the molarity of the diluted solution is 0.3 M
so
the answer is C) 0.3 M
7)
for omega-3-fatty acid
a C=C bond must exist at the 3 carbon bond from the hydrbophobic chain
so
the answer is option D
8)
for carboxylic acids
higher the alkyl chain , higher the melting point
so
the answer is option D
9)
the reaction is given by
CH3(CH2)16CH2COOH + CH3(CH2)7CH2OH ---> CH3(CH2)16CH2COOCH2(CH2)7CH3 + H20
so
the answer is option D
10)
the answer is option B
11)
we know that
pH = -log [H+]
pH = -log 3.5 x 10-8
pH = 7.456
so
the answer is A) 7.5
12)
pH = -log [H+]
8.2 = -log [H+]
[H+] = 10^(-8.2)
[H+] = 6.31 x 10-9
so
the answer is B) 6.31 x 10-9
13)
we know that
[OH-] > 10-7 , basic
[OH-] = 10-7 , neutral
[OH-] < 10-7 , acidic
given
[OH-] = 9.2 x 10-4
so
[OH-] > 10-7
so the solution is basic
the answer is B) basic
14)
we know that
for buffers
according to hasselbach hendersen eqaution
pH = pKa + log [conjugate base / acid]
also
pKa = -log Ka
so
pH = -log Ka + log [HP042- / H2P04-]
5.8 = -log 6.2 x 10-8 + log [HP042- / H2P04-]
[HP042- / H2P04-] = 0.039
so
the predominant species is H2P04-
so
the answer is C) H2P04-
15)
pH = -log [H+]
pH = -log 3.4 x 10-9
pH = 8.47
now
for pH > 8.3 , the red litmus will turn blue
in this case pH > 8.3
so
the answer is A) blue
16) there are 5 carbons
so it should be pentyl
the answer is D) pentyl
17)
hexanoic acid is D) CH3CH2CH2CH2CH2COOH
19)
the answer is B
20) it is D) heptanoate ion
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