CHEM 103
MODULE 6 2022
Question 1
Not yet graded / 10 pts
Click this link to access the Periodic Table. This may be helpful throughout
the exam.
List and explain if each of the following solutions conducts an electric
current: sodium chloride (NaCl), hydrochloric acid (HCl) and sugar (C6H12O6).
Sodium chloride (NaCl) is an ionic compound and conducts since it forms ions
in solution. Hydrochloric acid (HCl) is a polar compound and conducts since it
forms ions in solution. Sugar (C6H12O6) is a molecular compound but does not
form ions in solution so it does not conduct.
Question 2
Not yet graded / 10 pts
Explain how and why the presence of a solute affects the boiling point of a
solvent.
The presence of a solute raises the boiling point of a solvent by lowering the
vapor pressure of the solvent. With this lower vapor pressure, more heat (a
higher boiling point) is required to raise the vapor pressure to atmospheric
pressure.
Question 3
Not yet graded / 10 pts
Click this link to access the Periodic Table. This may be helpful throughout
the exam.
, Rank and explain how the freezing point of 0.100 m solutions of the following
ionic electrolytes compare, List from lowest freezing point to highest freezing
point.
GaCl3, Al2(SO4)3, NaI, MgCl2
Your Answer:
Al2(SO4)3 -> 2Al3+, 3SO4 -2
= = 5 ions -> most ions = lowest freezing
point
GaCl2 -> Ga3+, Cl- = 4 ions
MgCl2 = 3 ions
NaI = 2 ions - > least ions = highest freezing point
GaCl3 → Ga+3 + 3 Cl- ∆tf = 1.86 x 0.1 x 4 =
3rd lowest FP
3 SO4-3
Al2(SO4)3 → 2 Al+3 + ∆tf = 1.86 x 0.1 x 5 =
lowest FP
NaI → Na+ + I- ∆tf = 1.86 x 0.1 x 2
= highest FP
MgCl2 → Mg+2 + 2 Cl- ∆tf = 1.86 x 0.1 x 3
= 2nd lowest FP
FP: Al2(SO4)3 < GaCl3 < MgCl2 < NaI
Question 4
Not yet graded / 10 pts
Click this link to access the Periodic Table. This may be helpful throughout
the exam.
Show the calculation of the mass percent solute in a solution of 20.8 grams
of Ba(NO3)2 in 400 grams of water. Report your answer to 3 significant
figures.
MODULE 6 2022
Question 1
Not yet graded / 10 pts
Click this link to access the Periodic Table. This may be helpful throughout
the exam.
List and explain if each of the following solutions conducts an electric
current: sodium chloride (NaCl), hydrochloric acid (HCl) and sugar (C6H12O6).
Sodium chloride (NaCl) is an ionic compound and conducts since it forms ions
in solution. Hydrochloric acid (HCl) is a polar compound and conducts since it
forms ions in solution. Sugar (C6H12O6) is a molecular compound but does not
form ions in solution so it does not conduct.
Question 2
Not yet graded / 10 pts
Explain how and why the presence of a solute affects the boiling point of a
solvent.
The presence of a solute raises the boiling point of a solvent by lowering the
vapor pressure of the solvent. With this lower vapor pressure, more heat (a
higher boiling point) is required to raise the vapor pressure to atmospheric
pressure.
Question 3
Not yet graded / 10 pts
Click this link to access the Periodic Table. This may be helpful throughout
the exam.
, Rank and explain how the freezing point of 0.100 m solutions of the following
ionic electrolytes compare, List from lowest freezing point to highest freezing
point.
GaCl3, Al2(SO4)3, NaI, MgCl2
Your Answer:
Al2(SO4)3 -> 2Al3+, 3SO4 -2
= = 5 ions -> most ions = lowest freezing
point
GaCl2 -> Ga3+, Cl- = 4 ions
MgCl2 = 3 ions
NaI = 2 ions - > least ions = highest freezing point
GaCl3 → Ga+3 + 3 Cl- ∆tf = 1.86 x 0.1 x 4 =
3rd lowest FP
3 SO4-3
Al2(SO4)3 → 2 Al+3 + ∆tf = 1.86 x 0.1 x 5 =
lowest FP
NaI → Na+ + I- ∆tf = 1.86 x 0.1 x 2
= highest FP
MgCl2 → Mg+2 + 2 Cl- ∆tf = 1.86 x 0.1 x 3
= 2nd lowest FP
FP: Al2(SO4)3 < GaCl3 < MgCl2 < NaI
Question 4
Not yet graded / 10 pts
Click this link to access the Periodic Table. This may be helpful throughout
the exam.
Show the calculation of the mass percent solute in a solution of 20.8 grams
of Ba(NO3)2 in 400 grams of water. Report your answer to 3 significant
figures.
