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never [62]
3 years ago
9

An organic compound is 61.5% C, 2.56% H and 35.9% N by mass. 2.00 grams of this gas is entered into a 300.0 mL flask and heated

to 228 degrees C. At these conditions, the gas exerts a pressure of 2670 torr. Find the empirical formula.
Chemistry
1 answer:
pashok25 [27]3 years ago
6 0

Answer:

C₄H₂N₂

Explanation:

First we<u> calculate the moles of the gas</u>, using PV=nRT:

P = 2670 torr ⇒ 2670/760 = 3.51 atm

V = 300 mL ⇒ 300/1000 = 0.3 L

T = 228 °C ⇒ 228 + 273.16 = 501.16 K

  • 3.51 atm * 0.3 L = n * 0.082atm·L·mol⁻¹·K⁻¹ * 501.16 K
  • n = 0.0256 mol

Now we<u> calculate the molar mass of the compound</u>:

  • 2.00 g / 0.0256 mol = 78 g/mol

Finally we use the percentages given to<em> </em><u>calculate the empirical formula</u>:

  • C ⇒ 78 g/mol * 61.5/100 ÷ 12g/mol = 4
  • H ⇒ 78 g/mol * 2.56/100 ÷ 1g/mol = 2
  • N ⇒ 78 g/mol * 35.9/100 ÷ 14g/mol = 2

So the empirical formula is C₄H₂N₂

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pH = - log ( 1.71 x 10⁻³ ) = 3.8

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