HW2_Solutions

# 7 kjmol the normal 1 atm boiling point is 100 c using

• Notes
• 8

This preview shows page 5 - 8 out of 8 pages.

The heat of vaporization of water is 40.7 kJ/mol. The normal (1 atm) boiling point is 100 C. Using only this information, what is the vapor pressure of water at 35 C? 1. 0.0368 torr 2. 781. torr 3. 431. torr

Subscribe to view the full document.

estrada (gse77) – Homework 2 – Sutcliffe – (52410) 6 4. 82.6 torr 5. 4.61 torr 6. 47.8 torr correct 7. 28.0 torr Explanation: Use the Clausius-Clapeyron equation. 016 10.0 points How much energy is released when 150 g water at 52 C freezes and forms ice with a temper- ature of - 14 C? The specific heat of water in the liquid state is 4.18 J/g C, in the solid state is 2.09 J/g C, and in the gaseous state is 2.03 J/g C. The heat of fusion is 334 J/g and the heat of vaporization is 2260 J/g. 1. 22 kJ 2. 93 kJ 3. 102 kJ 4. 45 kJ 5. 87 kJ correct 6. 37 kJ Explanation: 017 10.0 points How many grams of water at 36.0 C must be added to 10.0 grams of ice at - 20 C to result in ONLY liquid water at 0 C? 1. 12.5 g 2. 1.25 g 3. 24.9 g correct 4. 21.2 g 5. 56.6 g 6. 74.0 g 7. 68.8 g 8. 22.4 g 9. 11.2 g 10. 109.2 g Explanation: The temperature of the 10.0 g ice must be raised from - 20 C to 0 C: q heat ice = m c Δ T = (10 . 0 g) parenleftbigg 2 . 09 J g · K parenrightbigg (20 C) = 418 J and then melted: q melt ice = m c = (10 . 0 g)(334 J / g) = 3340 J The total energy needed is 3758 J; this en- ergy comes from the the original water which must cool from 36.0 C to 0 C: q total = m c Δ T m = q c Δ T = 3758 J parenleftBig 4 . 184 J g · C parenrightBig (36 C) = 24 . 9495 g 018 (part 1 of 3) 10.0 points Refer to the following phase diagram for the next 3 questions.
estrada (gse77) – Homework 2 – Sutcliffe – (52410) 7 400 100 50 1 0.1 0.03 pressure (atm) temperature (K) 100 200 300 400 500 What is the critical temperature of this substance? 1. 525 K 2. 185 K 3. 475 K correct 4. 140 K 5. 320 K Explanation: The liquid/gas equilibrium line ends at the critical point which corresponds to a critical temperature of 475 K and a critical pressure of 85 atm. 019 (part 2 of 3) 10.0 points What is the state of the substance when it is at 1 atm and 250 K? 1. liquid correct 2. solid/liquid equilibrium 3. gas 4. its critical point 5. solid Explanation: Starting with the region adjacent to the pressure axis, the ordering is solid, liquid, and gas going clockwise. The intersection of 1 atm and 250 K is in the bottom portion of the liquid region. 020 (part 3 of 3) 10.0 points When the solid phase of this substance is sub- jected to a considerable amount of pressure it will 1. remain a solid. 2. melt. correct 3. go supercritical. 4. sublime. Explanation: The solid/liquid equilibrium line WILL ul- timately be crossed, as you go to higher and higher pressures. As you cross the line the solid phase will MELT into the liquid phase. 021 10.0 points Think this one over carefully, and you can use the phase diagram in the next question also if you wish. This is a SEALED container and we are only keeping the temperature constant (at 300K). When solid CO 2 (dry ice) is allowed to come to equilibrium in a closed constant volume container at room temperature (300 K), 1. the pressure rises until it reaches 1 atm.

Subscribe to view the full document.

You've reached the end of this preview.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern