Question

1 mole of O2 gas is heated quam 2700
to 67°c. If the value of change in
enthalpy is 7 x R , what is value of?​

Answer 1

Explanation:

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11th

Chemistry

Thermodynamics

Enthalpy

The difference in Δ H and Δ...

CHEMISTRY

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Asked on December 30, 2019 by

Aabharana Mallick

The difference in ΔH and ΔE for the combustion of methane at 27

o

C in calories would be:

MEDIUM

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ANSWER

Combustion of methane means the burning of methane in the presence of oxygen to give carbon dioxide and water.

The balanced reaction for combustion of methane is as follows:

CH

4

(g)+2O

2

(g)→CO

2

(g)+2H

2

O

In such reactions, the change in the number of moles is calculated for gaseous products only.

The number of moles of CH

4

, O

2

ans CO are 1, 1 and 2 respectively as seen from the balanced reaction given above.

Therefore, the change in the number of moles is given by =Δn

g

=n

products

−n

reactants

=1−(2+1) =−2

We know the relation: ΔH=ΔE+Δn

g

RT, where ΔH is the enthalpy change, ΔE is the internal energy change and Δn

g

is the change in the number of moles (as per the law of thermodynamics).

The value of gas constant (R) is 2 cal and temperature is 27

o

C or 300 K (given).

∴ΔH−ΔE=Δn

g

RT=−2×2×300 =−1200 calories

Hence, the difference in ΔH and ΔU for the combustion of methane at 27

o

C is −1200 cal.