A mass of 4.133g of sodium carbonate crystals Na2CO3.XH2O (s) was heated gently and 3.533g of anhydrous compound remained.Calcul
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Answer: Kc =5.915.
Explanation: Kc is an equilibrium constant of a chemical reaction and is dependent upon the reagents and products concentration. For this reaction, Kc is: Kc =
To determine each concentration, we have to find each relation:
From the reaction, we know that [NO] = 2[O2] (1)
From the Ideal Gas Law,
P·V=ntotal·R·T
[NO2]+{NO}+[O2] = = 0.015 mol/L
As [NO] = 2[O2]
[NO2]+2[O2]+[O2]=0.015
[NO2] = 0.015 - 3[O2] (2)
To resolve this equation, we will turn towards density of the mixture:
ρ =
Substituting mass for molar mass and number of molar,
ρ = M(NO2)·+M(NO)·
+M(O2)·
Knowing the molar mass of each molecule:
ρ = 46·[NO2]+30·[NO]+32·[O2] = 0.525 g/L (3)
Substituting (1), (2) and (3) we have:
46(0.015 - 3[O2])+30(2[O2])+32.[O2]=0.525
32[O2]+60[O2]-138[O2]=0.0525-0.69
-48[O2]= -0.6375
[O2]=13.3.M
Calculating for [NO]
[NO]=2[O2]
[NO]=2.13.3.
[NO]=26.6.M
And finding [NO2],
[NO2]=0.015 - 3[O2]
[NO2]=0.015 - 3.13.3.
[NO2]=39.885.M
So, to calculate Kc:
Kc = (26.6.)²· 13.3.
/ (39.885.
)²
Kc= 5.915.
The Kc is 5.915..