A model showing that gases are made from the matter of particles that are too small to see and are moving freely around in space can explain many observations.
Answer: 17.2 g
Explanation:
To calculate the moles :
The balanced chemical equation is:
According to stoichiometry :
4 moles of 
produce = 4 moles of 
Thus 0.085 moles of will require=
of
Mass of 
Thus 17.2 g of will be produced form 20.0 g of HgS.
There are several information's already given in the question. Based on those information's the answer can be easily determined.
M = <span>1.11 g CH4
C = </span>4.319 kJ g C⋅°
∆T = 35.65 - 24.85 degree centigrade
= 10.8 degree centigrade.
Then
∆H =−M ⋅ C ⋅∆T
= - 1.11 * 4.319 * 10.8
= - 51.776 kJ/<span>mol
I hope the procedure is clear enough for you to understand.</span>
