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Alla [95]
3 years ago
6

When 20.0 grams of an unknown compound are dissolved in 500. grams of benzene, the freezing point of the resulting solution is 3

.77°C. The freezing point of pure benzene is 5.48°C, and the Kf for benzene is 5.12°C/m. What is the molecular weight of the unknown compound?
Chemistry
1 answer:
Lelu [443]3 years ago
5 0

Answer: 120g/mol

Explanation:

The first step we are to take is to calculate the freezing point depression of the solution.

ΔT(f) = freezing point of pure solvent - freezing point of solution

ΔT(f) = 5.48 - 3.77

ΔT(f) = 1.71°C

Next we are to calculate the molal concentration of the solution using freezing point depression

ΔT(f) = K(f) * m

m = ΔT(f)/K(f)

m = 1.71/5.12

m = 0.333 molal

Now, we calculate the molecular weight of the unknown...

m = 0.333 mol = 0.333 mol X per kg of benzene

moles of X = 0.333 mol of X per kg of benzene * 0.5kg of benzene

moles of X = 0.1665

molecular weight of X = 20g of X/0.1665

molecular weight of X = 120/mol

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Answer:

Mg₁₂ = 1s² 2s² 2p⁶ 3s²

Explanation:

Abbreviated and unabbreviated electronic configuration:

The abbreviated electronic configuration uses the noble gas configuration i.e complete electronic shells. For example, the atomic number of neon is ten and magnesium is twelve. The abbreviated electronic configuration of magnesium is written by using the neon abbreviation in following way:

The electronic configuration of neon is given below:

Ne₁₀ = 1s² 2s² 2p⁶

The abbreviated electronic configuration of magnesium:

Mg₁₂ = [Ne] 3s²

While the unabbreviated electronic configuration is written without using noble gas electronic configuration.

Unabbreviated electronic configuration of magnesium:

Mg₁₂ = 1s² 2s² 2p⁶ 3s²

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How many significant figures are in 195.01
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An element's atomic number is 60. How many protons would an atom of this element have? __protons
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3 years ago
What change in volume results if 50 mL of gas is cooled from 30 C to 4 C
11111nata11111 [884]

The relation between the volume of the gas and the temperature is established by Charles's law. With a decrease in the temperature, the volume decreases by 45.7 mL. Thus, option c is correct.

<h3>What is Charle's law?</h3>

Charle's law states the direct relation present between the temperature and the volume of the gas. The law is given as:

V₁ ÷ T₁ = V₂ ÷ T₂

Given,

V₁ = 50 mL

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T₂ = 277.15 K

Substituting the value the final volume is calculated as:

50 ÷ 303.15 = V₂ ÷ 277.15

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Learn more about Charles law here:

brainly.com/question/16927784

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