Phase Diagram

Phase Diagram (C)

(B)

(D)

(A)

Honors Chemistry Chapter 13 Lecture Notes

Phase Particles Motion Effects of Pressure/ Temperature

Solid Tightly packed particles in a set structure

Liquid Packed but no set structures

Gas Very loosely held – the only thing that holds them together is their container

1. Phase Change Diagram

1. What does segment B-C represent?

2. What does segment A-B represent?

3. What does segment B-D represent?

4. What is the pressure at normal boiling point?

Why is this pressure significant?

5. What happens to the melting point of this substance as pressure increases?

6. What happens to the boiling point as pressure increases?

Heating and Cooling Curve

Which segments of the graph represent phase changes?

What is happening to the temperature while the

substance is changing phases?

Diagram Practice – Phase Diagrams and Heat/Cool Curves

Section 1- Creating Graphs (Heat/Cool Curves)

1. Graph temperature versus time for Water going from solid (ice) to gas (vapor). Make sure to label your axis and phase changes.

2. Graph temperature versus time of Nitrogen going from gas to liquid. Nitrogen condenses as (-210 degrees Celsius). Make sure to label your axis and phase changes.

3. Graph Temp. vs. time of Carbon Dioxide (CO

) going from gas to solid (dry ice).

Make sure to label your axes. Label to phases as well. (CO

sublimates at -78.5°C)

4. Graph Temp. vs. time of ethanol going from liquid to gas. Make sure to label your axes. Label to phases as well.

(Ethanol vaporizes at 78.1°C)

Section 2- Phase Change Diagram 1. What phase is this substance in at point A?

2. What phase is this substance in at point F?

3. What is the general term for what is happening at points BC and points DE?

4. What specifically is happening at points BC?

5. What specifically is happening at points DE?

6. What specifically is happening at points CB?

7. What specifically is happening at points ED?

8. At what point does this substance begin to freeze?

9. At what point does this substance begin to melt?

10. At what point does this substance begin to boil?

11. At what point does this substance begin to condense?

12. What is the freezing point of this substance?

13. What is the melting point of this substance?

14. What is the boiling point of this substance?

15. Describe an actual physical situation this graph may be representing (disregard exact temperatures).

Section 3- Phase Diagrams

Refer to the phase diagram below when answering the questions on this worksheet:

1) What is the normal freezing point of this substance? ________

2) What is the normal boiling point of this substance? ________

3) What is the normal freezing point of this substance? ________

4) If I had a quantity of this substance at a

pressure of 1.25 atm and a temperature of 300

C and lowered the pressure to 0.25 atm, what phase transition(s) would occur?

5) At what temperature do the gas and liquid phases become indistinguishable from each other?

6) At what temperature and pressure will all three phases coexist?

1. Which section represents the solid phase?

2. What section represents the liquid phase?

3. What section represents the gas phase?

4. What letter represents the triple point? In your own words, what is the definition of a triple point?

5. What is this substance’s normal melting point, at 1 atmosphere of pressure?

6. What is this substance’s normal boiling point, at 1 atmosphere of pressure?

7.Above what temperature is it impossible to liquefy this substance, no matter what the pressure?

8. At a constant temperature, what would you do to cause this substance to change from the liquid phase to the solid phase?

9. What does sublimation mean?

Honors Chemistry Lecture Notes Ch 14 Gases:

Gas Law Practice Problems – You Must SHOW ALL WORK for Complete Credit!!!!

Boyles Law- moles and temperature are constant

1. At 700.mmHg a sample of hydrogen has a volume of 500.mL. If the pressure is decreased to 538mmHg, what will the new volume be?

2. At 8:00am, a sample of potassium chlorate is decomposed to yield a solid and 50.0ml of a gas at 720.mmHg. By 5:00 pm, the volume had changed to 53.0mL. What was the atmospheric pressure at 5:00pm? What was the gas produced from the decomposition?

3. If the pressure of 50.0L of oxygen is .921atm, what will be the pressure if the volume changed to 60.0L?

4. If a gas occupies 25.0mL at 119.96kPa, what volume will it occupy at STP [standard temperature(0ºC) and pressure (1 atm)]

5. Calculate the volume of gas if the original volume of 2.00L at 700. mmHg is subjected to a pressure of 1000.mmHg.

Charles’ Law – moles and pressure are constant

6. A sample of carbon dioxide has a volume of 100.mL at 273K. What volume will it occupy at 300.K?

7. A balloon holds 250.mL of a gas at 290.K. What will the volume be at 20.°C?

8. To what temperature must 580.mL of oxygen at 17.0°C be raided to increase its volume to 700.mL?

9. If 600.0mL of hydrogen are collected when the temperature is 27.0°C, what volume will the gas occupy at 254.0°C?

10. Student A and B perform the same experiment in which they decompose a compound to obtain a gas.

Student A collects 5.00L of the gas at 25.0°C. Student B collects 4.85 L of the gas at 22.0°C. The theoretical yield of the reaction is 4.97L at STP. What are the percent yields for each student? Write a balanced equation for a possible decomposition that the student could have used.

Gay-Lussac’s law – moles and volume are constant

11. If a container of hydrogen at 15.00mmHg and 23.0 °C is heated to 46.0°C, what is the pressure of the gas?

12. Calculate the temperature of nitrogen gas is 2.00L of the gas at STP is subjected to a pressure of 920.mmHg.

Combined Gas Law – moles held constant

13. A great chemistry teacher with superior lab skills collects 250.mL of dangerous hydrogen chloride gas at 27.0°C and .987atm. When reporting her data she will have to adjust her volume to STP conditions. What volume should she record?

14. A sample of nitrogen gas occupies 20.0mL at 27.0°C and 800.mmHg of pressure is warmed to 50.0°C and allowed to expand to 43.mL. What pressure does the gas exert?

15. A gas sample has a volume of 50.0mL when measured under a pressure of 740.mmHg and 25.0°C what will the volume be at STP?

16. What would be the temperature if 50.0mL of a gas at STP were compressed under 199.9kPa to 30.0mL?

Ideal Gas Law

17. A student collects 425mL of oxygen gas at a temperature of 24.0°C and a pressure of 0.889atm. How many moles of oxygen did the student collect? How many grams of oxygen is this?

18. An engineer pumps 5.00 moles of carbon monoxide gas into a cylinder that has a capacity of 20.0L. What is the pressure of the cylinder (expressed in kPa) at 25.0°C?

19. 100.0mL of a gas is collected in a very large test tube. The weight of the gas in the test tube is 2.62g.

The gas was collected at 697.68mmHg and 10.0°C. What is the molar mass of the gas collected?

20. A student collects a gas from the decomposition of solid magnesium carbonate. If 305.0mL of the gas was captured at 22.0°C and 99.8kPa. How many grams of the carbonate decomposed, assuming none of the gas was lost?

Choose the Correct Law and Solve

21. A balloon was purchased in a store at 25.0°C. It contained 1000.mL of helium. When taken outside, it contained only 950mL of the gas. What is the temperature outside the store?

22. A blimp contains 1000.L of hydrogen gas at 760.mmHg of pressure. If the temperature remained

constant and the blimp grew to a volume of 1050L over 24 hours, what would be the atmospheric pressure after 24 hours? What is the rate of expansion in L/hr?

23. A liter of oxygen at STP is heated to 300. °C what is the new pressure at a constant volume?

24. A 500.0mL sample of methane at 600.mmHg and 27.0°C is heated to 127.0°C while the pressure is increased to 1000.mmHg. What is the new volume of the gas?

Answers:

1) 651mL 2) 679mL 3)583mmHg 4)29.6mL 5)1.40L 6) 110.mL 7) 253mL 8)350.K

9)1050.mL 5)

11) 16.2mmHg 12)57.5°C 13)225mL 14)401mmHg 15)45.0mL 16)50.0°C 17)0.495g

18)620 kPa 19)663 g/mol 20)1.04g 21)10.0°C 22)724mmHg 23)1.60 x 10

mmHg 24)400.0mL

Ideal Gas Law Stoichiometry Lecture Problems

1. When 4.50 g of magnesium chlorate decomposes at 800.C, 5.94L of the gas is collected at 774.0mmHg.

What is the percent yield for the reaction?

2. 1.15 g of magnesium is placed in 150.0mL of 0.100M hydrochloric acid. What volume of gas could be collected at 25.0C and 742.0mmHg. If a student captures 149.0mL, what is the students percent yield?

3. How many grams of nitrogen are needed to produce 48.6 liters of ammonia (NH

) at 10.0C and 70.91Kpa?

4. An unknown metal having a 2

oxidation state with a mass of 0.033g is reacted with excess sulfuric acid. 12.5 mL of gas was collected at 23.0 C and 755.0mmHg. What is the molar mass of the metal? Identify the metal.

5. What volume of chlorine gas at 20.0C and 0.92 atm is needed to react with 4.60 g of sodium metal to form sodium chloride? What is the theoretical mass of sodium chloride that could be formed?

Answers:

1) 97.2% 2) .19.L, 78.4% 3)20.5g 4)64.6 g/mol 5)5.2L, 23.5 gNaCl