Answer:
a) 
b) entropy of the sistem equal to a), entropy of the universe grater than a).
Explanation:
a) The change of entropy for a reversible process:
The energy balance:
![\delta U=[tex]\delta Q- \delta W](https://tex.z-dn.net/?f=%5Cdelta%20U%3D%5Btex%5D%5Cdelta%20Q-%20%5Cdelta%20W)
If the process is isothermical the U doesn't change:
![0=[tex]\delta Q- \delta W](https://tex.z-dn.net/?f=0%3D%5Btex%5D%5Cdelta%20Q-%20%5Cdelta%20W)
The work:
If it is an ideal gas:
Solving:
Replacing:
Given that it's a compression: V2<V1 and ln(V2/V1)<0. So:
b) The entropy change of the sistem will be equal to the calculated in a), but the change of entropy of the universe will be 0 in a) (reversible process) and in b) has to be positive given that it is an irreversible process.
The much of the sample that would remain unchanged after 140 seconds is 2.813 g
Explanation
Half life is time taken for the quantity to reduce to half its original value.
if the half life for Scandium is 35 sec, then the number of half life in 140 seconds
=140 sec/ 35 s = 4 half life
Therefore 45 g after first half life = 45 x1/2 =22.5 g
22.5 g after second half life = 22.5 x 1/2 =11.25 g
11.25 g after third half life = 11.25 x 1/2 = 5.625 g
5.625 after fourth half life = 5.625 x 1/2 = 2.813
therefore 2.813 g of Scandium 47 remains unchanged.
Its a compound because they come together
0.20 moles of iron will be formed in the reaction.
Explanation:
The balanced chemical equation for the reaction between iron (iii) oxide and carbon monoxide to form Fe is to be known first.
the balanced reaction is :
Fe2O3 + 3CO⇒ 2 Fe + 3 CO2
so from the data given the number of moles of carbon monoxide can be known:
3 moles of CO reacted with Fe2O3 to form 2 moles of iron in the reaction.
Number of moles of CO is 6.20 moles
11.6 gm of iron is formed
so the number of moles of iron formed is calculated as
n = mass of iron ÷ atomic weight of iron
= 11.6 ÷ 55.84
= 0.20 moles of iron will be formed when 11.6 gram of iron is produced.
