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2 years ago

What is the approximate difference in energy between the two chair conformations of trans-2-methyl-1-isopropylcyclohexane?

1 answer:

dsp732 years ago

7 0

In the conformer I, both the substituents are in axial positions. Methyl group has two 1, 3 diaxial (H----CH_3) interactions and isopropyl group has two 1, 3 diaxial (H----pr) interactions. Therefore, the energy of these interactions is given as (2x0.9) + (2x1.1) = 4.0kCal/mol.

In conformer II both the substituents are equatorial positions. So, axial interactions are absent and one gauche interaction between isopropyl and methyl groups exists therefore, the energy of this interaction is given as 1.1kCal/mol. The difference in the energy of two conformations is calculated as

E = (1.0 – 1.1) kCal/mol = 2.9 kCal/mol

The answer to the question is 2.9 kCal/mol

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A 5.024 mg sample of an unknown organic molecule containing carbon, hydrogen, and nitrogen only was burned and yielded 13.90 mg

Dafna1 [17]

Answer:

C8H17N

Explanation:

Mass of the unknown compound = 5.024 mg

Mass of CO2 = 13.90 mg

Mass of H2O = 6.048 mg

Next, we shall determine the mass of carbon, hydrogen and nitrogen present in the compound. This is illustrated below:

For carbon, C:

Molar mass of CO2 = 12 + (2x16) = 44g/mol

Mass of C = 12/44 x 13.90 = 3.791 mg

For hydrogen, H:

Molar mass of H2O = (2x1) + 16 = 18g/mol

Mass of H = 2/18 x 6.048 = 0.672 mg

For nitrogen, N:

Mass N = mass of unknown – (mass of C + mass of H)

Mass of N = 5.024 – (3.791 + 0.672)

Mass of N = 0.561 mg

Now, we can obtain the empirical formula for the compound as follow:

C = 3.791 mg

H = 0.672 mg

N = 0.561 mg

Divide each by their molar mass

C = 3.791 / 12 = 0.316

H = 0.672 / 1 = 0.672

N = 0.561 / 14 = 0.040

Divide by the smallest

C = 0.316 / 0.04 = 8

H = 0.672 / 0.04 = 17

N = 0.040 / 0.04 = 1

Therefore, the empirical formula for the compound is C8H17N

8 0

2 years ago

In the first step of glycolysis, the given two reactions are coupled. reaction 1:reaction 2:glucose+Pi⟶glucose-6-phosphate+H2OAT

dmitriy555 [2]

Answer: Reaction 1 is non spontaneous.

Explanation:

According to Gibb's equation:

$\Delta G=\Delta H-T\Delta S$

$\Delta G$ = Gibbs free energy

$\Delta H$ = enthalpy change

$\Delta S$ = entropy change

T = temperature in Kelvin

When $\Delta G$ = +ve, reaction is non spontaneous

$\Delta G$ = -ve, reaction is spontaneous

$\Delta G$ = 0, reaction is in equilibrium

For the given reaction 1: $glucose+Pi\rightarrow glucose-6-phosphate+H_2O$ $\Delta G=+13.8kJ/mol$

As for the reaction 1 , the value of Gibbs free energy is positive and thus the reaction 1 is non spontaneous.

6 0

2 years ago

An unknown solid is entirely soluble in water. On addition of dilute HCl, a precipitate forms. After the precipitate is filtered

Karo-lina-s [1.5K]

Answer:

Pb(NO3)2

Cd(NO3)2

Na2SO4

Explanation:

In the first part, addition of HCl leads to the formation of PbCl2 which is poorly soluble in water. This is the first precipitate that is filtered off.

When the pH is adjusted to 1 and H2S is bubbled in, CdS is formed. This is the second precipitate that is filtered off.

After this precipitate has been filtered off and the pH is adjusted to 8, addition of H2S and (NH4)2HPO4 does not lead to the formation of any other precipitate.

The yellow flame colour indicates the presence of Na^+ which must come from the presence of Na2SO4.

5 0

1 year ago

You have two compounds that you have spotted on the TLC plate. One compound is more polar than the other. You ran the TLC plate

goldenfox [79]

Answer:

we will except an increase in the polarity of the system and this will cause the Non-polar spot to be near the solvent front, while the polar spot will run at an approximate speed of 0.5 Rf

Explanation:

when we run a TLC plate in a 50/50 mixture of hexanes and ethyl acetate we will except an increase in the polarity of the system and this will cause the Non-polar spot to be near the solvent front, while the polar spot will run at an approximate speed of 0.5 Rf

The speed of the polar spot depends largely on the level of polarity, an increase in the polarity will see both spots of Neat hexane run when we run a TLC plate in a 50/50 mixture of hexanes and ethyl acetate

3 0

2 years ago

Alka‑Seltzer is marketed as a remedy for stomach problems, such as heartburn or indigestion, and pain relief. It contains aspiri

Papessa [141]

Answer:

The equation for the reaction of one sodium bicarbonate ( NaHCO3 ) molecule with one citric acid (C6H8O7) molecule is the following:

Sodium Bicarbonate + Citric Acid ⇒ Water + Carbon Dioxide + Sodium Citrate

NaHCO3 + C6H8O7 ⇒ 3 CO2 + 3 H2O + Na3C6H5O7

Explanation:

The reaction is in balance, that is, the whole H2CO3 is not finished, but a little bit of this acid is left in the solution. Therefore, when sodium bicarbonate is added to the solution with citric acid, sodium citrate salt (C6H5O7Na3) and carbonic acid (H2CO3) are formed, which is rapidly broken down into water (H2O) and carbonic oxide (CO2).

C6H8O7 + NaHCO3 ⇒ C6H5O7Na3 + 3 H2CO3

C6H5O7Na3 + 3 H2CO3 ⇔ C6H5O7Na3 + 3 H2O + 3 CO2

5 0

2 years ago