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fenix001 [56]
3 years ago
7

Paradichlorobenzene, C6H4Cl2, is a component of mothballs. A solution of 2.00 g in 22.5 g of cyclohexane boils at 82.39 ∘C. The

boiling point of pure cyclohexane is 80.70 ∘C. Calculate Kb for cyclohexane. Express the constant numerically in degrees Celsius per molal.
Chemistry
1 answer:
Rina8888 [55]3 years ago
4 0

Answer:

2.79 °C/m

Explanation:

When a nonvolatile solute is dissolved in a pure solvent, the boiling point of the solvent increases. This property is called ebullioscopy. The temperature change (ΔT) can be calculated by:

ΔT = Kb*W*i

Where Kb is the ebullioscopy constant for the solvent, W is the molality and i is the van't Hoff factor.

W = m1/(M1*m2)

Where m1 is the mass of the solute (in g), M1 is the molar mass of the solute, and m2 is the mass of the solvent (in kg).

The van't Hoff factor represents the dissociation of the elements. For an organic molecule, we can approximate i = 1. Thus:

m1 = 2.00 g

M1 = 147 g/mol

m2 = 0.0225 kg

W = 2/(147*0.0225)

W = 0.6047 mol/kg

(82.39 - 80.70) = Kb*0.6047*1

0.6047Kb = 1.69

Kb = 2.79 °C/m

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Answer:

4190.22 L = 4.19 m³.

Explanation:

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<em>2P₂ + 5O₂ ⇄ 2P₂O₅. </em>

It is clear that 2 mol of P₂ react with <em>5 mol of O₂ </em>to produce <em>2 mol of P₂O₅.</em>

  • Firstly, we need to calculate the no. of moles of 6.92 kilograms of P₂O₅ produced through the reaction:

no. of moles of P₂O₅ = mass/molar mass = (6920 g)/(283.88 g/mol) = 24.38 mol.

  • Now, we can find the no. of moles of O₂ is needed to produce the proposed amount of P₂O₅:

<u><em>Using cross multiplication:</em></u>

5 mol of O₂ is needed to produce → 2 mol of P₂O₅, from stichiometry.

??? mol of O₂ is needed to produce → 24.38 mol of P₂O₅.

∴ The no. of moles of O₂ needed = (5 mol)(24.38 mol)/(2 mol) = 60.95 mol.

  • Finally, we can get the volume of oxygen using the general law of ideal gas:<em> PV = nRT.</em>

where, P is the pressure of the gas in atm (P = 606.1 mm Hg/760 = 0.8 atm).

V is the volume of the gas in L (V = ??? L).

n is the no. of moles of the gas in mol (n = 60.95 mol).

R is the general gas constant (R = 0.0821 L.atm/mol.K),

T is the temperature of the gas in K (396.90°C + 273 = 669.9 K).

∴ V of oxygen needed = nRT/P = (60.95 mol)(0.0821 L.atm/mol.K)(669.9 K)/(0.8 atm) = 4190.22 L/1000 = 4.19 m³.

3 0
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Ymorist [56]

Answer:

the answer is below

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Cirrus clouds form from the ascent of dry air, making the small quantity of water vapour in the air undergo deposition into ice (to change from a gas directly into a solid). Cirrus is made up completely of ice crystals, which provides their white colour and form in a wide range of shapes and sizes.

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What is the number of the group that has the most reactive nonmetals (give number and letter- Ex 1A, 2A, etc.)?​
Kryger [21]

Answer:

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Explanation:

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This group is known as the group of halogens. They consist of element fluorine, chlorine, bromine, iodine and astatine.

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The chemical equation for the reaction of sodium hypochlorite and water follows:

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By Stoichiometry of the reaction:

1 mole of sodium hypochlorite reacts with 1 mole of water to produce 1 mole of hypochlorous acid and 1 mole of sodium hydroxide.

Hence, when bleach is mixed with water, it produces hypochlorous acid.

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