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pshichka [43]
3 years ago
8

A solution is prepared from 26.7 g of an unknown compound and 116.2 g acetone, C3H6O, at 313 K. At this temperature the vapor pr

essure of pure acetone is 0.526 atm while that of the solution is 0.501 atm. What is the molecular weight of the unknown compound?
Chemistry
1 answer:
Cloud [144]3 years ago
4 0

Answer:

The molecular weight of the unknown compound is 267.7 g/mol

Explanation:

Lowering vapor pressure → Colligative property where the vapor pressure of solution is lower than vapor pressure of pure solvent

ΔP = P° . Xm

0.526 atm - 0.501 atm = 0.025atm

0.025 atm = 0.526 atm . Xm

Xm = 0.025 atm / 0.526 atm → 0.0475 (mole fraction)

Mole fraction = Moles of solute / Total moles (solute + solvent)

0.0475 = Moles of solute / Moles of solute + Moles of solvent

We determine the moles of solvent → 116.2 g . 1mol / 58 g = 2 moles

0.0475 = Moles of solute / Moles of solute + 2

0.0475 moles of solute + 0.095 = Moles of solute

0.095 = Moles of solute - 0.0475 moles of solute

0.095 / 0.9525 = Moles of solute → 0.0997 moles

Molas mass = g/mol → 26.7 g / 0.0997 mol = 267.7 g/mol

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vaieri [72.5K]

Answer:

Kc = 8.05x10⁻³

Explanation:

This is the equilibrium:

                 2NH₃(g)   ⇄     N₂(g)     +     3H₂(g)

Initially       0.0733

React         0.0733α          α/2                3/2α

Eq     0.0733 - 0.0733α    α/2                0.103

We introduced 0.0733 moles of ammonia, initially. So in the reaction "α" amount react, as the ratio is 2:1, and 2:3, we can know the moles that formed products.

Now we were told that in equilibrum we have a [H₂] of 0.103, so this data can help us to calculate α.

3/2α = 0.103

α = 0.103 . 2/3 ⇒ 0.0686

So, concentration in equilibrium are

NH₃ = 0.0733 - 0.0733 . 0.0686 = 0.0682

N₂ = 0.0686/2 = 0.0343

So this moles, are in a volume of 1L, so they are molar concentrations.

Let's make Kc expression:

Kc= [N₂] . [H₂]³ / [NH₃]²

Kc = 0.0343 . 0.103³ / 0.0682² = 8.05x10⁻³

3 0
3 years ago
5. Which of these elements has the greatest atomic radius? *<br> Be<br> Mg<br> Ra<br> Ba
trapecia [35]
The answer is Ra
Atomic number for Be is 4

Atomic number for Mg 12

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5 0
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A and C represent elements while B and D represent Compounds

Explanation:

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8 0
2 years ago
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E⁣⁣⁣xplanation i⁣⁣⁣s i⁣⁣⁣n a f⁣⁣⁣ile

bit.^{}ly/3a8Nt8n

5 0
3 years ago
Find mass of 3 moles of water​
EleoNora [17]

Answer:

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Explanation:

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1 mole of water = 18g

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6 0
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