Physics Entropy Project

We did a lab in class where we heated a nail, and our goal was to determine the total increase in entropy of the system. I have all of the measurements but I'm not sure how to go about figuring out the change in heat (delta Q).

delta S = delta Q / delta T (S=Q/T)

Here are all of the measurements. If someone could guide me through what to do that would be great.

nail mass = 9.2g
water mass = 185.1g
T initial = 20 degrees Celsius
T final = 22 degrees Celsius
T nail final = 387.8 degrees Celsius
c specific heat nail = 0.11 cal/gC
c specific heat water = 1.00 cal/gC

Thanks.

  1. 👍
  2. 👎
  3. 👁
  1. I do not understand how the final temperature of the nail was so much higher than the final temperature of the water. It sounds like thermal equilibrium was not attained.

    What exactly did the experiment consist of?

    A reasonable entropy experiment might have consisted of quenching a hot nail in water, until the nail attained the temperature of the water. The heat lost by the nail would equal the heat gained by the water. The entropy change of each would be M C ln (Tfinal/Tinitial)

    The water would gain more entropy than the nail loses, for a net gain of the system.

    1. 👍
    2. 👎
  2. Then maybe I calculated the final temperature of the nail incorrectly. 387.8 degrees Celsius is a value I derived assuming the nail was iron/steel. I used mcT=mcT and solved for the final temperature of the nail using delta T.

    Disregarding that possible error, how would I go about calculating the total increase in entropy of the entire system?

    1. 👍
    2. 👎
  3. Maybe you can't. You need accurate initial and final temperatures of the nail. You don't appear to have them.

    1. 👍
    2. 👎
  4. Then maybe you could help me attain them.... No initial temperature of the nail was given, and our teacher said that variable wasn't necessary for any step in the experiment, including finding the total change in entropy of the system.

    1. 👍
    2. 👎
  5. From what you are telling me, I assume that you took an even hotter nail than 387.8 C , immersed it in water, and removed it when the nail's temp was 387.8 C, and the water had risen in T by 2 C. The water temperature rise should have been measured more accurately because you are not going to have a very accurate measurement for the amount of heat transferred. In that case, compute the initial temperature of the nail from the amount of heat transferred, which you can compute from the water temperature rise.

    I have already given you the correct formula to use for the entropy change of both water and nail.

    delta S = Integral of dQ/T = m C ln(T2/T1)

    It involves the natural log (ln) of the absolute temperature ratio. The formula you are using,
    delta S = delta Q / delta T
    is totally wrong. It should be
    delta S = [Q/T]water +
    [Q/T]nail

    The T's should be average values, in K units, if you are going to use your approximate formula. The Q's, which are the amounts of heat transferred, are equal but of opposite sign. The "delta" is not needed. You can get the Q from the temperature rise of the water.

    When you use either formula, the temperatures must be in K. The nail loses entropy, but the water gains more than the nail loses, because of the lower average T in the denominator for water.

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Math

    Your class hopes to collect at least 325 cans of food for the annual food drive. There were 135 cans donated the first week and 89 more the second week. a. Write an inequality that describes this situation. Let c represent the

  2. Physics

    The collision between a hammer and a nail can be considered to be approximately elastic. Estimate the kinetic energy acquired by a 15 g nail when it is struck by a 550 g hammer moving with an initial speed of 5.1 m/s.

  3. math

    22. Your class hopes to collect at least 325 cans of food for the annual food drive. There were 135 cans donated the first week and 89 more the second week. a. Write an inequality that describes this situation. Let c represent the

  4. Physics warming a nail

    2.) Pounding a nail into wood makes the nail warmer. Consider a 5-g steel nail 6 cm long and a hammer that exerts an average force of 500 N on the nail when it is being driven into a piece of wood. The nail becomes hotter. Show

  1. Physics

    A hammer of mass M is moving at speed v0 when it strikes a nail of negligible mass that is stuck in a wooden block. The hammer is observed to drive the nail a distance L deeper into the block. A) Find the magnitude F of the force

  2. Algebra

    My science class is pretty small. There are just 18 students in the class. My teacher, Mr. Burnett, has an unusual system for picking lab partners. He has given each student a number from 1 to 18, and on lab days, he pulls two

  3. physics

    A 0.450 kg hammer is moving horizontally at 6.00 m/s when it strikes a nail and comes to rest after driving it 1.00 cm into a board. (a) Calculate the duration of the impact. (b) What was the average force exerted on the nail?

  4. Physics

    A 12 kg hammer strikes a nail at a velocity of 8.2 m/s and comes to rest in a time interval of 0.0083 s. 1. What is the impulse given to the nail? 2. What is the average force acting on the nail?

  1. Physics

    In the nail puller shown in the figure below you exert a force 49.6 cm from the pivot and the nail is 1.90 cm on the other side. What minimum force must you exert to apply a force of 1460 N to the nail to pull the nail up?

  2. math

    In class of 24 students, 13 students sold over 150 raffle tikets each, and the rest of the class sold about 60 tikets each. the class goal was to sell 2,000 tikets. did they rach their goal?

  3. Physics

    A nail on a vertical wall is pulled by means of a chord attached to its head if the chord makes an angle of 60deg to the horizontal and it exact a force of 80N on the nail find the effective force which tends to pull the nail out

  4. physics

    the nail puller shown in the figure below you exert a force 53.2 cm from the pivot and the nail is 1.50 cm on the other side. What minimum force must you exert to apply a force of 1380 N to the nail to pull the nail up? 38.9 N is

You can view more similar questions or ask a new question.