write a relation between delta G and Q and define the meaning of each term and answer the following

a) why a reaction proceeds forward when Q< K and no net reaction occurs when Q = K

b) explain the effect of increase in pressure in terms of reaction quotient Q for the reaction CO ⇆ CH4(g) + H2O(g)

(ii) for the reaction,

N2(g) +3H2(g)⇆ 2NH(g)

at 400K , Kp = 41, find the value Kp for the reaction

2N2(g) +6H2(g) ⇆ 4NH3(g)

Asked by gganga | 10th Apr, 2018, 06:02: PM

Expert Answer:

Relation space between space increment straight G space and space straight Q space is comma

increment straight G space equals space increment straight G to the power of degree space plus space RT space lnQ

Where comma

increment straight G space equals Gibb apostrophe straight s space energy space change

space increment straight G to the power of degree equals space Standard space Gibb apostrophe straight s space energy space change

straight R equals space Gas space constant

straight T equals space Absolute space temperature

straight Q equals space Reaction space quotient

left parenthesis straight a right parenthesis space
space space space space space As comma space space increment straight G to the power of degree space end exponent equals space minus RT space lnK

therefore space increment straight G space equals space minus RT space lnK space plus space RT space lnQ

space space space space space space space space space space space equals RT space lnQ minus RT space lnK space

space space space space increment straight G equals space RT space ln straight Q over straight K

If space straight Q greater than space straight K comma space then space increment straight G space will space be space negative.
Reaction space proceeds space in space straight a space forward space direction.

If space straight Q equals space straight K comma space then space increment straight G equals space 0 comma space no space net space reaction space occurs.

left parenthesis straight b right parenthesis
space space space space CO subscript open parentheses straight g close parentheses end subscript space space plus 3 space straight H subscript 2 open parentheses straight g close parentheses end subscript space rightwards harpoon over leftwards harpoon space CH subscript 4 open parentheses straight g close parentheses end subscript space plus space space straight H subscript 2 straight O

straight K subscript straight c space equals fraction numerator open square brackets CH subscript 4 close square brackets open square brackets straight H subscript 2 straight O close square brackets over denominator open square brackets space space CO close square brackets open square brackets space straight H subscript 2 close square brackets cubed end fraction

On space increasing space the space pressure space the space volume space is space decreased space and space hence comma space molar space concentartion space increases.
If space the space pressure space is space doubled comma space molar space concentartion space will space also space be space doubled.

straight Q equals fraction numerator 2 open square brackets CH subscript 4 close square brackets 2 open square brackets straight H subscript 2 straight O close square brackets over denominator 2 open square brackets space space CO close square brackets open square brackets 2 space straight H subscript 2 close square brackets cubed end fraction

equals 1 fourth fraction numerator open square brackets CH subscript 4 close square brackets open square brackets straight H subscript 2 straight O close square brackets over denominator open square brackets space space CO close square brackets open square brackets space straight H subscript 2 close square brackets cubed end fraction

therefore straight Q equals 1 fourth straight K subscript straight c

Answered by Varsha | 11th Apr, 2018, 01:10: PM