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2 years ago

For a 0.50 molal solution of sucrose in water, calculate the freezing point and the boiling point of the solution.

Chemistry

1 answer:

jok3333 [9.3K]2 years ago

6 0

Answer:

-0.93 °C; 100.26 °C

Step-by-step explanation:

(a) Freezing point depression

The formula for the freezing point depression ΔT_f is

ΔT_f = iKf·b

i is the van’t Hoff factor: the number of moles of particles you get from a solute.

For sucrose,

Sucrose (s) ⟶ sucrose (aq)

1 mole sucrose ⟶ 1 mol particles i = 1

ΔT_f = 1 × 1.86 × 0.50

ΔT_f = 0.93 °C

T_f = T_f° - ΔT_f

T_f = 0.00 – 0.93

T_f = -0.93 °C

(b) Boiling point elevation

The formula for the boiling point elevation ΔTb is

ΔTb = iKb·b

ΔTb = 1 × 0.512 × 0.50

ΔTb = 0.256 °C

Tb = Tb° + ΔTb

Tb = 100.00 + 0.256

Tb = 100.26 °C

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What is the theoretical yield of fluorenone if you oxidize 175 mg of fluorene?

My name is Ann [436]

Answer:

602 mg of CO₂ and 94.8 mg of H₂O

Explanation:

The yield is measured by the amount of each product produced by the reaction.

The chemical formula of fluorene is C₁₃H₁₀, and its molar mass is 166.223 g/mol.

The oxidation, also know as combustion, of this hydrocarbon is represented by the following balanced chemical equation:

$2C_{13}H_{10}+31O_2\rightarrow 26CO_2+10H_2O$

To calculate the yield follow these steps:

1. Mole ratio

$2molC_{13}H_{10}:31molO_2:26molCO_2:10molH_2O$

2. Convert 175mg of fluorene to number of moles

$175mg/times 1g/1,000mg=0.175g$

Number of moles = mass in grams / molar mass

$\text{number of moles}=0.175g/166.223g/mol=0.0010528mol$

3. Set a proportion for each product of the reaction

a) For CO₂

i) number of moles

$2molC_{10}H_{13}/26molCO_2=0.0010528molC_{10}H{13}/x$

$x=0.0010528molC_{10}H_{13}\times 26molCO_2/2molC_{10}H_{13}=0.013686molCO_2$

ii) mass in grams

The molar mass of CO₂ is 44.01g/mol

mass = number of moles × molar mass

mass = 0.013686 moles × 44.01 g/mol = 0.602 g = 602mg

b) For H₂O

i) number of moles

$0.0010528molC_{10}H_{13}\times10molH_2O/2molC_{10}H_{13}=0.00526molH_2O$

ii) mass in grams

The molar mass of H₂O is 18.015g/mol

mass = number of moles × molar mass

mass = 0.00526 moles × 18.015 g/mol = 0.0948mg = 94.8 mg

4 0

3 years ago

This chemical reaction is unbalanced: ___Pb(NO₃)₂(aq) + ___Li₂SO₄(aq) → ____PbSO₄(s) + ____LiNO₃(aq) Which coefficient should ap

kakasveta [241]

Answer: 2

Explanation:

4 0

3 years ago

Write a balanced molecular equation for hydrochloride acid solution combined with a potassium hydroxide solution, an acid base r

qaws [65]

Answer:

HCl (aq) + KOH (aq) --------> KCl (aq) + H2O (l) [balanced molecular equation]

Explanation:

Balanced molecular equation has all the components of reaction written as "molecules" thus the name molecular (the other equations break appropriate components into ions, those are total ionic or net ionic equation)

We know hydrochloride acid solution is written as HCl (aq) and potassium hydroxide solution is written as KOH (aq). We know from our knowledge that when acids react with bases they make salt and water, so now we react!

HCl (aq) + KOH (aq) --------> KCl (aq) + H2O (l) [balanced molecular equation]

7 0

2 years ago

Calculate the oxidation state of the underlined elements of K2 Cr2 O7

Semenov [28]

Answer:

Explanation:

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⇒ x + (−2) + (−2) = 0

x = +4

So the oxidation no. of Pb is +4.

I hope this helps.

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2 years ago

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ivann1987 [24]

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2 years ago