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daser333 [38]
2 years ago
5

4. a compound called pyrene has the empirical formula c8h5. when 4.04 g of pyrene is dissolved in 10.00 g of benzene, the boilin

g point of the solution is 85.1°c calculate the molar mass of pyrene and determine its molecular formula. the molal boiling-point constant for benzene is 2.53°c/m. its normal boiling point is 80.1°c
Chemistry
1 answer:
e-lub [12.9K]2 years ago
3 0

The molecular mass of pyrene is 204.4 g/mol.

From;

ΔT = Kb m i

Where;

  • ΔT = boiling point elevation
  • Kb = boiling point constant
  • m = molality
  • i = Van't Hoff factor

Since the compound is molecular; i = 1

The number of moles of pyrene = 4.04 g/MM

Where; MM = molar mass of pyrene

molality = number of moles of pyrene/mass of solvent in Kg

The mass of solvent = 10 g or 0.01 Kg

molality =  4.04 g/MM/0.01

ΔT = Boiling point of solution - Boiling point of pure solvent

ΔT = 85.1°C - 80.1°C

ΔT = 5°C

5 = 2.53 × 4.04 g/MM/0.01 × 1

5 = 10.22 × 1/0.01 MM

0.05MM = 10.22

MM= 10.22/0.05

MM= 204.4 g/mol

Learn more: brainly.com/question/2292439

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Answer:5.4 g / 13.6 g *100

Explanation:Its is the correct answer

7 0
3 years ago
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How many grams of hydrogen are produced if 30.0 g of zinc reacts?
alekssr [168]
<span>0.925 grams if using hydrochloric acid in the reaction. 0.462 grams if using sulfuric acid in the reaction. 0.000 grams if using nitric acid in the reaction. Assuming you're using HCl or a similar acid for this reaction, the equation for the reaction is: Zn + 2 HCl ==> ZnCl2 + H2 So each mole of zinc used, produces 1 mole of hydrogen gas, or 2 moles of hydrogen atoms. So we need to look up the atomic weights of both zinc and hydrogen. Atomic weight zinc = 65.38 Atomic weight hydrogen = 1.00794 Moles zinc = 30.0 g / 65.38 g/mol = 0.458855919 mol Since we produce 2 moles of hydrogen atoms per mole of zinc, multiply by 2 and the atomic weight of hydrogen to get the mass of hydrogen produced. So 0.458855919 * 2 * 1.00794 = 0.92499847 grams. Rounding to 3 significant figures gives 0.925 grams. To show the assumption of the acid used, the balanced equation for sulfuric acid would be Zn2 + H2SO4 ==> Zn(SO4)2 + H2 Which means that for every mole of zinc used, 1 mole of hydrogen gas is generated (half that produced via hydrochloric acid). If nitric acid were used, the reaction is 4Zn + 10HNO3 ==> 4Zn(NO3)2 + N2O + 5H2O Which means that NO hydrogen gas is generated. The only justification for assuming hydrochloric acid is used is that it's a fairly common acid that's easy to obtain. But as shown above with 2 alternative acids, the amount of hydrogen gas generated is very dependent upon the exact chemical reaction occurring and asking "How many grams of hydrogen are produced if 30.0 g of zinc reacts?" is a rather silly question unless you specify EXACTLY what the reaction is.</span>
3 0
3 years ago
a sealed container filled with argon gas at 35 c has a pressure of 832 torr. if the volume of the container is decreased by a fa
lesya692 [45]

Answer:

If the volume of the container is decreased by a factor of 2 the pressure is is increased by the same factor to 1664 torr.

Explanation:

Here we have Boyle's law which states that, at constant temperature, the volume of a given mass of gas is inversely proportional to its pressure

V ∝ 1/P or V₁·P₁ = V₂·P₂

Where:

V₁ = Initial volume

V₂ = Final volume = V₁/2

P₁ = Initial pressure = 832 torr

P₂ = Final pressure  = Required

From V₁·P₁ = V₂·P₂ we have,

P₂ = V₁·P₁/V₂ = V₁·P₁/(V₁/2)

P₂  = 2·V₁·P₁/V₁ = 2·P₁ = 2× 832 torr = 1664 torr

6 0
3 years ago
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6 0
2 years ago
How many hydrogen atoms are in 5.20 mol of ammonium sulfide?
Fofino [41]
1) Molecular formula of ammonium sulfide

(NH4)2 S

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3) To pass to number of atoms multiply by Avogadro's number: 6.022 * 10^23

41.6 moles * 6.022 * 10^23 atoms / mol = 250.5 * 10^23 = 2.50 * 10^25 atoms

Answer: 2.50 * 10^25
8 0
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