more CHEM proofreading

posted by .

for this question A sample of air has a volume of 140.0 mL at 67 degrees celcius. At what temperature would its volume 50.0 mL at constant pressure
I did
140.0 ml... 67+273=340
T2... 50.0
140.0=50.0
340=T2
340*50.0/140.0=121.4

This question i don't get because of the scientific notation. A sample of oxygen that occupies 1.00 x 10^6 mL at 575 mm Hg is subjected to a pressure of 1.25 atm. What will the final volume of the sample be if the temp is held constant?

  • more CHEM proofreading -

    The first one is ok EXCEPT that if your prof is a stickler for significant figures, you will get points counted off if not the entire question. The smallest number of significant figures is 3 (50.0, 340) so the most s.f. you are allowed in the answer is 3; therefore, you would round the answer to 121. ALSO, some profs will count off if you don't have units; therefore, the complete answer would be 121 Kelvin.
    For the second problem, 10^6 just means to add 6 zeros to 1 (which would be 1,000,000). Or you can key in the number with scientific notation to your calculator and let it keep track of the decimal. USUALLY, a number expressed as 1.00 x 10^6 mL means your prof looks at s.f.

  • more CHEM proofreading -

    ok i get that now.. but now im still confused with how to solve the problem because i don't see where it talks about temperature.

  • more CHEM proofreading -

    Sure. It says the temperature is held constant. This is a pressure/volume problem. Done the same way except
    P1V1 = P2V2.

    By the way, do you know how to keep all these formulas straight? Do it this way.
    The general formula is
    (P1V1)/T1 = (P2V2)/T2
    If T is constant, just cover up T1 and T2 with your fingers (or mentally) and you have P1V1 = P2V2 which is Boyle's Law.
    If P is held constant, cover up P1 and P2 with your fingers (or mentally), and you have V1/T1 = V2/T2 which is Charles' Law.
    If V is held constant, covert up V1 and V2 with yur fingers (or mentally) and you have P1/T1 = P2/V2. Easy, huh?
    You only need to memorize the general formula that contains all the variable and tailor it to fit the problem. And, of course, you must remember that T always goes in with Kelvin.

  • more CHEM proofreading -

    If V is held constant, covert up V1 and V2 with yur fingers (or mentally) and you have P1/T1 = P2/V2. Easy, huh?

    I made a goof here. This should read, if V is held constant, cover up V1 and V2 with your fingers (or mentally) and you have P1/T1 = P2/T2
    My fingers sometimes get ahead of my brain.

  • more CHEM proofreading -

    well im sure u can tell chemistry is my weakest subject because im still confused :/...

    so would it be 1000000= 575
    1.25= t2?

  • more CHEM proofreading -

    Why do you want to solve for t? It SAYS t is constant so we don't care what it is. And you haven't used the pressure at all.
    You didn't do what I said. Just follow the guide lines.
    P1V1/T1 = P2V2/T2.
    Now, since T is constant, cover T1 and T2 with your fingers, or mentally, and we are left with
    P1V1 = P2V2
    Now look at the problem.
    V1 = 1 x 10^6 mL
    P1 = 575 mm Hg
    V2 = ?? mL.
    P2 = 1.25 atm.
    Right away you see that the units on pressure don't match. You must change mm Hg to atmospheres OR change atmospheres to mm Hg. The conversion factor is 760 mm = 1 atm. The easy one to change is P1 so 575/760 = 0.756 atm.
    Then P1V1 = P2V2
    0.756*1x10^6 = 1.25*V2 and solve for V2.

  • more CHEM proofreading -

    ok thank you for all of your help tonight.. i really appreciate it!

  • more CHEM proofreading -

    You're welcome.

  • more CHEM proofreading -

    p1v1/t1=p2vp/t2;v2

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. chem

    A sample of fluorine has a volume of 3.6 L when the temperature is 112.3 degC and the pressure is 922 torr. What will be the volume when the pressure is 88.48 kPa and the temperature is 140.4 degC?
  2. chemistry

    a sample of air has a volume of 140.0 mL a 67 degrees C. at what temperature would its volume be 50.0 mL at constant pressure/
  3. chemistry

    i keep trying to do these problems and i don't understand them. please help me!! 1. Gas stored in a tank at 273 K has a pressure of 388 kPa. The save limit for the pressure is 825 kPa. At what temperature will the gas reach this pressure?
  4. chemistry

    a sample of air has a volume of 140.0 mL at 67 degrees C. At what temperature will its volume be 50.0 mL at constant pressure?
  5. nuclear physics

    A researcher wishes to extract 140 La from 140 Ba. She obtains a 1000 MBq virgin Ba-140 sample and must wait until the maximum activity of La-140 is available. a) Write down the decay relationship (include half-lives), and include …
  6. Chemistry

    A sample of air has a volume of 140.0 mL at 67 degrees Celsius. At what temperature would its volume be 50.0 mL at constant pressure?
  7. Physics

    A cylindrical tank has a tight-fitting piston that allows the volume of the tank to be changed. The tank originally contains 0.140 m3 of air at a pressure of 3.20 atm. The piston is slowly pulled out until the volume of the gas is …
  8. AP Chemistry

    Suppose that a sample of gas occupies 140 mL of volume at 25C and a pressure of 252 torr. What would be the volume if the pressure were changed to 552 torr at 25C?
  9. science

    Part I: Units of Measurement for Gas Laws For the following questions, use the following answer choices to indicate what each unit of measurement is used to measure (pressure, volume, or temperature). 1. atm 2. kPa 3. L 4. oC 5. torr …
  10. chem

    A sample of air has a volume of 140.0 mL at 67 Degrees Celsius.?

More Similar Questions