CHEM 103 M3: EXAM - REQUIRES RESPONDUS LOCKDOWN BROWSER +
WEBCAM PORTAGE LERANING
Question 1
pts
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A reaction between HCl and NaOH is being studied in a styrofoam coffee cup
with a lid and the heat given off is measured by means of a thermometer
immersed in the reaction mixture. Enter the correct thermochemistry term
to describe the item listed.
1. The type of thermochemical process
2. The calorimeter and mixture of HCl + NaOH
Your Answer:
1. Heat given off = Exothermic process
2. With lid = closed system
Question 2
10/ 10 pts
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, 1. Show the calculation of the final temperature of the mixture when a
22.8 gram sample of water at 74.6oC is added to a 14.3 gram sample of
water at 24.3oC in a coffee cup calorimeter.
c (water) = 4.184 J/g oC
2. Show the calculation of the energy involved in freezing 54.3 grams of
water at 0oC if the Heat of Fusion for water is 0.334 kJ/g
Your Answer:
1. - (mwarn H2O x cwarn H2O x ∆twarn H2O) = (mcool H2O x ccool H2O x ∆tcool H2O)
- [22.8 g x 4.184 J/g oC x (Tmix - 74.6oC)] = [14.3 g x 4.184 J/g oC x (Tmix -
24.3oC)]
- [95.3952 J/oC x (Tmix - 74.6oC)] = [59.8312 J/oC x (Tmix - 24.3oC)]
Tmix = 55.2oC
2. ql↔s = m x ∆Hfusion = 54.3 g x 0.334 kJ/g = 18.14 kJ (since heat is removed)
= - 18.14 kJ
Question 3
pts
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Show the calculation of the ΔH of the reaction if 20.7 g of S is reacted with
excess O2 to yield 255.6 kJ and sulfur trioxide by the following reaction
equation. Report your answer to 4 significant figures.
2 S (s) + 3 O2 (g) → 2 SO3 (g)
Your Answer:
https://www.stuvia.com/user/Mboffin
WEBCAM PORTAGE LERANING
Question 1
pts
You may find the following resources helpful:
Scientific Calculator
Periodic Table
Equation Table Download Equation Table
A reaction between HCl and NaOH is being studied in a styrofoam coffee cup
with a lid and the heat given off is measured by means of a thermometer
immersed in the reaction mixture. Enter the correct thermochemistry term
to describe the item listed.
1. The type of thermochemical process
2. The calorimeter and mixture of HCl + NaOH
Your Answer:
1. Heat given off = Exothermic process
2. With lid = closed system
Question 2
10/ 10 pts
You may find the following resources helpful:
Scientific Calculator
Periodic Table
Equation Table Download Equation Table
https://www.stuvia.com/user/Mboffin
, 1. Show the calculation of the final temperature of the mixture when a
22.8 gram sample of water at 74.6oC is added to a 14.3 gram sample of
water at 24.3oC in a coffee cup calorimeter.
c (water) = 4.184 J/g oC
2. Show the calculation of the energy involved in freezing 54.3 grams of
water at 0oC if the Heat of Fusion for water is 0.334 kJ/g
Your Answer:
1. - (mwarn H2O x cwarn H2O x ∆twarn H2O) = (mcool H2O x ccool H2O x ∆tcool H2O)
- [22.8 g x 4.184 J/g oC x (Tmix - 74.6oC)] = [14.3 g x 4.184 J/g oC x (Tmix -
24.3oC)]
- [95.3952 J/oC x (Tmix - 74.6oC)] = [59.8312 J/oC x (Tmix - 24.3oC)]
Tmix = 55.2oC
2. ql↔s = m x ∆Hfusion = 54.3 g x 0.334 kJ/g = 18.14 kJ (since heat is removed)
= - 18.14 kJ
Question 3
pts
You may find the following resources helpful:
Scientific Calculator
Periodic Table
Equation Table Download Equation Table
Show the calculation of the ΔH of the reaction if 20.7 g of S is reacted with
excess O2 to yield 255.6 kJ and sulfur trioxide by the following reaction
equation. Report your answer to 4 significant figures.
2 S (s) + 3 O2 (g) → 2 SO3 (g)
Your Answer:
https://www.stuvia.com/user/Mboffin
