Question

Check my answers please? Only 5...Will reward medal to best answer and perhaps become a fan! :)

1. Which curve or point of a phase diagram would indicate the melting point at various temperatures and pressures?

triple point
fusion curve <---
sublimation curve
critical point

Answer 1

2. Refer to the phase diagram for substance X.

http://takeexam.next.ecollege.com/CurrentCourse/VHS_CHEM_S2_01_14_Q2.gif

In the phase diagram for substance X, what is the triple point of substance X?
0°C, 0 atm
22°C, 4 atm
60°C, 5 atm
29°C, 2.2 atm <---

Answer 2

3. According to this phase diagram of water, what happens when you increase the pressure from 50 kPa to 150 kPa on an ice cube at 0°C?

http://takeexam.next.ecollege.com/ec/pub/K12Content/Courses/resources/swfs/media/Ninth_Grade/Science/Unit17465/Lesson68584/VHS_CHEM_S2_01_17_112_water_phase_quiz.gif

The ice cube sublimes.
The ice cube remains solid. <--- I think it's this one but I'm not for sure. It might be C.
The ice cube melts.

Answer 3

4. Which of the following occurs when the temperature and pressure are below the triple point of a substance?

The substance melts to a liquid.
Only the solid form of the substance can exist.
Only the gaseous form of the substance can exist. <--- or is it D?
The substance cannot exist in the liquid form.

Answer 4

5. Refer to the phase diagram for carbon dioxide.

http://takeexam.next.ecollege.com/CurrentCourse/VHS_CHEM_S2_01_14_Q5.gif

For a given sample of carbon dioxide (CO2) you increase the temperature from 80°C to 0°C and decrease the pressure from 30 atm to 5 atm. On a phase diagram this causes a crossing of both the solid-liquid boundary and the liquid-gas boundary. Which of the following best describes what happens?

The solid sublimes to gas.
The gas condenses to liquid and then freezes solid.
The gas deposits directly into a solid.
The solid melts to liquid and then vaporizes to gas. <--- This one?

Answer 5

Now looking at it...4 is definitely D. And 3 is probably C huh? Are they all correct? What do you think? Am I right?

Answer 6

1 looks right to me.

Answer 7

Ok, what about the others?

Answer 8

I can't see the links because I can't log in to your course. Can you take a screenshot?

Answer 9

I agree with your change to D for. 4.

Answer 10

Sorry! Hold on, just one sec...

Answer 11

No worries. :)

Answer 12

5 looks right from the wording.

Answer 13

2 looks right.

Answer 14

Awesome! Thank you so much!

Answer 15

By the way, for 5, a change in temp from 80 to 0 wouldn't be an increase.

Answer 16

Whoops! -80 forgot the negative sign

Answer 17

Makes sense. :)

Answer 18

I didn't see a phase diagram for 3. I looked up one but it is hard to tell whether it stays solid or melts.

Answer 19

I found another one that looks pretty definitively like it melts.

Answer 20

Awesome! Thank you so much! I really appreciate it. Just turned it in and got a 100%!

Answer 21

No worries. Glad I could help. You got most of them right yourself. High five!