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2 years ago

What is the freezing point (in degrees Celcius) of 4.14 kg of water if it contains 235.1 g of butanol, C 4 H 9 O H

Chemistry

1 answer:

Karolina [17]2 years ago

5 0

Answer:

Explanation:

Molal freezing point depression constant of butanol Kf = 8.37⁰C /m

ΔTf = Kf x m , m is no of moles of solute per kg of solvent .

mol weight of butanol = 70 g

235.1 g of butanol = 235.1 / 70 = 3.3585 moles

3.3585 moles of butanol dissolved in 4.14 kg of water .

ΔTf = 8.37 x 3.3585 / 4.14

= 6.79⁰C

Depression in freezing point = 6.79

freezing point of solution = - 6.79⁰C .

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Answer:

True

Explanation:

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2 years ago

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mel-nik [20]

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Detecta cuál de las siguientes fórmulas estructurales no cumple con la tetravalencia del carbono (formar cuatro enlaces)

o-na [289]

El ejercicio completo con las formulas es el siguiente:

cuál de las siguientes fórmulas no cumple con la tetravalencia del átomo de carbono.

a. CH3-CH2-CH2-OH

b. CH3-CH=CH2

c. CH3-CH2=CH2

d. CH3-CH2-CH3

Answer:

La respuesta correcta es la opción C

Explanation:

En la formula C, podemos ver claramente que no se cumple con la tetravalencia del carbono pues al sumar el total de las valencias del carbono nos da 5

CH3 - CH2 = CH2 = Total de valencias del carbono 5

1 + 2+ 2 = 5

Para que la formula sea correcta debe eliminarse un hidrogeno quedando la formula de la siguiente manera:

CH3 - CH = CH2

1 + 1 + 2 = 4

8 0

2 years ago

The cyclohexane ring is essentially free of ring strain because Check all that apply.

NikAS [45]

Answer:The following statements are correct: 1,2 and 6

Explanation:

1.The cyclohexane ring adopts a chair conformation in order to minimize its torsional strain. In chair conformation 4 carbon atoms are in one plane 1 carbon atom is above that plane and the other 1 carbon atom is below that plane .This leads to chair conformation in which the bond angles are very close to the ideal tetrahedral angle of 109.5 degrees. The C-C-C bond angle in chair conformation is 110 degrees which is almost equal to the ideal tetrahedral angle.

2. In cyclohexane molecule as the molecule adopts a chair conformation in order to eliminate the torsional strain which would occur if the cyclohexane ring were to be planar. Torsional strain is basically the inter electronic repulsion between the atoms that do not share a bond. So this strain happens on account of eclipsing atoms. In case of eclipse structure there would be a lot of torsional strain. In case of chair conformation all the C-H bonds happen to be completely staggered in nature to eliminate the torsional strain.

3. The ring strain in case of cycloalkanes are dependent upon the number of CH₂ groups present as that would determine the size of the ring and subsequently its structure ,whether the ring would be 5 , 6 or 7 membered .Cyclohexane is a 6 -membered as there are 6CH₂ groups in it and the existence of chair conformation is only for Cyclohexane or for molecules having 6-membered ring . Any change in number of CH₂groups would lead to a different conformational structure.

4.All the bond angles in cyclohexane ring is approximately 110 degrees which is almost equal to the ideal terahedral bond angle. So the bond angles in cyclohexane are optimal.

5.The C-H bonds in cyclohexane are always staggered and never eclipsed in order to reduce there torsional strain.

6.All the bonds in cyclohexane ring are staggered to eliminate the torsional strain. It is quite evident that the cyclohexane ring is completely stable free of the ring strain.So there are no eclipsing bonds present in cyclohexane.

So the statements which are correct 1,2 and 6

4 0

3 years ago

A 1.555-g sample of baking soda decomposes with heat to produce 0.991 g Na2CO3. Refer to Example Exercise 14.l and show the calc

Sunny_sXe [5.5K]

Answer:

a) 101%

b)59.7%

Explanation:

The equation for the thermal decomposition of baking soda is shown;

2NaHCO3 → Na2CO3 + H2O + CO2

Number of moles of baking soda= mass/molar mass= 1.555g/84.007 g/mol = 0.0185 moles

From the reaction equation;

2 moles of baking soda yields 1 mole of sodium carbonate

0.0185 moles of baking soda will yield = 0.0185 moles ×1 /2 = 9.25 ×10^-3 moles of sodium carbonate.

Therefore, mass of sodium carbonate= 9.25 ×10^-3 moles × 106gmol-1= 0.9805 g of sodium carbonate. This is the theoretical yield of sodium carbonate.

%yield = actual yield/theoretical yield ×100

% yield = 0.991/0.9805 ×100

%yield = 101%

Since ;

2NaHCO3 → Na2CO3 + H2O + CO2

And H2O + CO2 ---> H2CO3

Hence I can write, 2NaHCO3 → Na2CO3 + H2CO3

Molar mass of H2CO3= 62.03 gmol-1

Molar mass of baking soda= 84 gmol-1

Therefore, mass of baking soda=

0.325/62.03 × 2 × 84 = 0.88 g of NaHCO3

% of NaHCO3= 0.88/1.473 × 100 = 59.7%

7 0

2 years ago