ISA for the term

Heat and thermodynamics.

Learning objective

10.2.2.1 - apply the ideal gas equation of state and distinguish gas process graphs;

10.2.3.1-explain the meaning of the first and second laws of thermodynamics

10.2.3.2-describe the operation and application of the heat engine;

10.2.4.1-determine relative humidity;

10.2.4.2-explain the nature of surface tension and the role of capillary phenomena in everyday life;

PART1:  MULTIPLE CHOICE QUESTIONS

Instructions:

·         For each question there are five possible answers A, B, C, D and E. Choose the one you consider the best and correct. 

·         Mark your answers to multiple choice questions in the space provided below.

Begin Here:

1.      An ideal gas in a cylinder with a movable piston is made to follow the process  graphed  by  the  path  A→B→C→A.  What  work   done  of the  gas?  

1.

A  20 J                                                                                                                                                                                                                   B  40 J                                                                                                                                                                                                               C  60  J                                                                                                                                                                                                         D  80  J

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2 What is the rms speed of nitrogen molecules contained in 6.4 m³  volume at 4.2 atm if the total amount of nitrogen is 1800 mol?

A  100 m/s                                                                                                                                                                                              B  200 m/s                                                                                                                                                                                                        C  400 m/s                                                                                                                                                                                                                     D  800 m/s

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3.Thirty joules of heat flow into a system. The system in turn does 50 joules of work. The internal energy of the system has                                                                                                                                                                                 A  increased by 80 J                                                                                                                                                                                          B  decreased by 80 J                                                                                                                                                                                     С  increased by 20 J                                                                                                                                                                                      D  decreased by 20 J

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4.  A gas is taken from an initial state to a final state as shown. How much work is done during this

process?

A  5 kJ                                                                                                                                                                                                                   B   6 kJ                                                                                                                                                                                                                   C   7 kJ                                                                                                                                                                                                                   D   8 kJ

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5.  An ideal gas absorbs 750 J of heat in the process of an isobaric expansion. What is the resulting change in temperature if there are 3 moles of the gas in the system?

A  12 K                                                                                                                                                                                                                  B   16 K                                                                                                                                                                                                                  C   20 K                                                                                                                                                                                                                  D   24 K                                                                                                                                                                                                                  

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6. Which are graphs represents an isochoric process

A  5,9,10                                                                                                                                                                                                                  B   5,6,10                                                                                                                                                                                                                  C  4,8,9                                                                                                                                                                                                                  D  5,9,12                                                                                                                                                                                                                   

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7.What is the relative humidity for following readings?

A   48%                                                                                                                                                                                                                 B   52%                                                                                                                                                                                                                  C   55%                                                                                                                                                                                                                  D   58%                                                                                                                                                                                                                   

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8.Which can increase the relative humidity?

A   increase air temperature                                                                                                                                                                                                                 B   decrease air temperature                                                                                                                                                                                                                 C   increase dew point                                                                                                                                                                                                             D  decrease dew point                                                                                                                                                                                                                

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 9.Water rises to a height of 20 mm in a capillary. If the radius of the capillary is made 1/3 rd of its previous value, to what height will the water now rise in the tube?

A  40 mm                                                                                                                                                                                                                 B  60 mm                                                                                                                                                                                                                 C  80 mm                                                                                                                                                                                                                  D  90 mm                                                                                                                                                                                                                  

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10.Water rises in a glass capillary tube to a height of 9 cm. What is the diameter of the capillary tube? Surface tension of 72.0 mN/m.

A  0.08 mm                                                                                                                                                                                                                 B  0.16 mm                                                                                                                                                                                                                 C  0.32 mm                                                                                                                                                                                                                  D  0.48 mm                                                                                                                                                                                                                   

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PART 2:  SHORT-ANSWER QUESTION

Instructions:

·         Read each question carefully.

·         Answer all the questions.

·         Show all calculations and write your answer in the space provided.

11. A system of monatomic ideal gas contains a certain number of moles of gas so that nR=0.200 J/K . The system                                                                              is taken from state 5 to state 6 (see Figure 15.25) by an unknown sequence of processes.  

                                                                                                                                                                                                                  a. What is the temperature of the system in state 6?  ______[1]                                                                                                                                                                                                          b. What is the work done by the gas as the system moves from state 5 to state 6?  _____[1]                                                                                                                                     c. What is the change in internal energy of the gas as it moves from state 5 to state 6?_________[1]

12.  An engine absorbs 1.60 kJ from a hot reservoir  and expels 1.20 kJ to a cold reservoir  in each cycle.                     

 a. What is the engine’s efficiency?__________[1]                                                                                                                       b. How much work is done by the engine in each cycle?_________[1]                                                                                                              c. What is the power output of the engine if each cycle lasts 0.25 s?______[1]

13. 2500 J of heat is added to a system, and 1800 J of work is done on the system. What is the change in internal energy  of the system? _________[2]

14. A steam engine operates  between 500°C and 270°C. What is the maximum possible efficiency of this engine?_________[2]

15. A mercury drop of radius 10^-3 m breaks up into 125 small droplets. Calculate the change in energe assuming that the drops are spherical and surface tension of the mercury is 0.55 N/m. ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________[4]

16. A needle 5 cm long can just rest on the surface of water without wetting. What its weight? Surface tension of water = 0.07 N/m. _________[2]

PART 3:  LONG ANSWER QUESTIONS

Instructions:

·         Read each question careful.

·         Answer all the questions.

·         If the question requires calculation, show all work and your complete solution.

17. The chart shows the change of state of the ideal gas in coordinate plane pressure against temperature. 1-2-3-1

a.Draw new charts to show changes of state of the ideal gas in coordinate planes the pressure against volume and the volume against temperature

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To determine the amount of heat in each process, if n=3 moles and T= 400 K

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To find a job in the cycle _______________________________________________________________________________________________________________________________________________________________________________________________________________________________[2]