Thermochemistry | Chemistry homework help

Chemistry Final Exam        Version  12/2016

Name:

Student number: 

Directions: It is important that you provide answers in your own words.  Please focus only on information from the text/eBook to create your own solutions.  Please do not use direct information from an outside source (especially copying and pasting from an “answer” website). Use of direct information from an outside source is against school policy.  All answers will be checked for plagiarism.  Instances of plagiarism can result in probation or possible dismissal from the school. 

Please be sure to follow all guidelines (number of sentences/showing all calculations) and to provide the correct metric units of measure.  All questions are 3.33 points each (.33 for unit)

1. A student collected the following data for a fixed volume of gas:

Temperature (⁰C)

Pressure (mm of Hg)

10

726

20

750

40

800

70

880

100

960

150

???

Fill in the missing data point.  Show all calculations leading to an answer.

1. You are given a clear solution of KNO3.  Using 3 – 4 sentences (in your own words) explain how you would determine if the solution is unsaturated, saturated or supersaturated.
2. Explain why gasoline will not dissolve in water.
3. Explain in 3 – 4 sentences (in your own words) how perspiration helps keep you cool on a hot day.
4. You have two sealed jars of water at the same temperature.  In the first jar there is a large amount of water.  In the second jar there is a small amount of water.  Using 3 -4 sentences explain how the vapor pressure of water in the first jar compares with the vapor pressure of water in the second jar.
5. Using 3 – 4 sentences explain (in your own words) why water expands when it freezes?
6. Using your knowledge of colligative properties explain whether sodium chloride or calcium chloride would be a more effective substance to melt the ice on a slick sidewalk.  Use 3 – 4 sentences in your explanation.
7. When a 2.5 mol of sugar (C12H22O11) are added to a certain amount of water the boiling point is raised by 1 Celsius degree.  If 2.5 mol of aluminum nitrate is added to the same amount of water, by how much will the boiling point be changed?  Show all calculations leading to your answer OR use 3 – 4 sentences to explain your answer.
8. If 5.40 kcal of heat is added to 1.00 kg of water at  100⁰C, how much steam at 100⁰C is produced?  Show all calculations leading to an answer.
9. The freezing of water at 0⁰C can be represented as follows: 

H2O (l) ↔ H2O(s)

The density of liquid water is 1.00 g/cm3.  The density of ice is 0.92 g/cm3.  In 3 – 4 sentences explain why applying pressure causes ice to melt.

1. The Kw of water varies with temperature.  Calculate the pH of water at 46⁰C with a Kw = 1.219 x 10-14.  Show all calculations leading to an answer.
2. Calculate the hydroxide ion concentration of a solution with pH = 3.25.  Show all calculations leading to an answer.
3. What salt results from the neutralization of phosphoric acid with potassium hydroxide?
4. What is the oxidation number of chlorine in Al(ClO4)3?
5. Which element is oxidized in the following reaction:

CuO(s) + H2 (g) → Cu(s) + H2O (l)

1. Why must the number of electrons lost equal the number of electrons gained in every redox reaction?  Use 3 – 4 sentences in your own words to address this question. 
2. The following unbalanced equation describes the reaction that can occur when lead (II) sulfide reacts with oxygen gas to produce lead (II) oxide and sulfur dioxide gas:

PbS + O2 → PbO + SO2

Balance the equation and describe in words the electron transfer(s) that takes place.

1. What type of radiation is emitted when chromium-51 decays into manganese-51?  Show the nuclear equation that leads you to this answer.
2. A radioactive nucleus alpha decays to yield a sodium-24 nucleus in 14.8 hours.  What was the identity of the original nucleus?  Show the nuclear equation that leads you to this answer.
3. Iron-59 has a half-life of 45.1 days.  How old is an iron nail if the Fe-59 content is 25% that of a new sample of iron?   Show all calculations leading to a solution.
4. Using at least 3 to 4 complete content related sentences, explain how the compressed gas in an aerosol can forces paint out of the can.  Be sure to describe how the gas pressure inside the can changes as the paint is sprayed.  Please refer to figure 14.5 in lesson 14.1. 
5. pH is a measure of ______________.
6. hydrogen ion concentration.  c.  hydroxide ion concentration.
7. hydrogen gas concentration.  d.  hydrolysis.
8. A neutralization reaction between an acid and a base always produces
9. salt and acidic anhydride.   c.  water and basic anhydride.
10. salt and basic anhydride.   d.  salt and water.
11. If the pH of a solution is _____ the solution is basic.

a.  2  b.  5  c.  7  d.  10

25 – 30  Apply the appropriate word to the definition indicated. Not all words will be used.  

25. _____

Heat content of a system at constant pressure 

calorie (cal)

26. _____

Ability to do work 

Chemical Potential Energy

27. _____

Disorder 

Energy

28. _____

Energy of motion 

Enthalpy

29. _____

Study of energy changes that ocrrue during chemic reaction and changes in states. 

Entropy

30. _____

Amount of heat required to raise T of 1 g of pure water 1◦C

Joule

Kinetic energy

Heat (q)

Specific Heat

Thermochemistry