Ask Question
13 November, 01:10

A plasma-screen TV contains thousands of tiny cells filled with a mixture of Xe, Ne, and He gases that emits light of specific wavelengths when a voltage is applied. A particular plasma cell, 0.900 mm*0.300mm*10.0mm, contains 4.00%Xe in a 1:1 Ne : He mixture at a total pressure of 500. torr. Assumptions: In order to calculate total moles of gas and total atoms, we assumed a reasonable room temperature. Since '4.00% Xe' was not defined, we conveniently assumed mole percent. The 1:1 relationship of Ne to He is assumed to be by volume and not by mass. Part A) Calculate the number of Xe atoms in the cell. Part B) Calculate the number of Ne atoms in the cell. Part C) Calculate the number of He atoms in the cell.

+5
Answers (1)
  1. 13 November, 04:32
    0
    (a) 1.77*10^15 Xe atoms

    (b) 2.10*10^16 Ne atoms

    (c) 2.10*10^16 He atoms

    Explanation:

    Total V = 0.900 mm * 0.300mm * 10.0mm

    Total V = 2.7mm cubed

    Converting cubed to litres:

    2.7mm cubed = 2.7 * 10^-6 Liters

    Converting pressure from torr to atm,

    (500 torr) * (1 atm : 760 torr) = 0.6578947368 atm

    Room temperature is assumed to be 21 degrees celcius, or 294.15 Kelvin

    Applying Ideal Gas Equation:

    PV = nRT

    Therefore, n = PV : RT,

    n = [ (2.7*10^-6 Liters) (.6578947368 atm) ] : [ (0.08206) (294.15) ]

    n = 7.359017079 * 10^-8

    Therefore, the total moles present in plasma is 7.359017079 * 10^-8.

    (a) To find Xe atoms,

    Multiply the total moles present by 4 percent. Therefore,

    (7.359017079 * 10^-8) (.04) = 2.943606832*10^-9,

    this value gives you Xe moles.

    Then multiply by Avogadro's constant:

    [ (2.943606832*10^-9) (6.022*10^23) ] = 1.77*10^15 Xe atoms

    (b) and (c) are the same.

    Using the total moles number we found in the beginning and minus the number of moles for Xe.

    We have:

    7.359017079 * 10^-8 - 2.943606832*10^-9 = 7.064656396*10^-8

    And Since Ne and He are in a 1:1 ratio, divide this number by two.

    We have:

    7.064656396*10^-8 : 2 = 3.532328198*10-8 moles

    By multiplying this number by Avogadro's number we get atoms:

    [ (3.532328198*10-8 moles) (6.022*10^23) ] = 2.10*10^16

    Therefore, the answer for both (b) and (c) is 2.10*10^16.
Know the Answer?
Not Sure About the Answer?
Find an answer to your question ✅ “A plasma-screen TV contains thousands of tiny cells filled with a mixture of Xe, Ne, and He gases that emits light of specific wavelengths ...” in 📘 Chemistry if you're in doubt about the correctness of the answers or there's no answer, then try to use the smart search and find answers to the similar questions.
Search for Other Answers