Lead (Pb) has been used for centuries. The Romans used it in their plumbing systems - the symbol for lead (Pb plumbus). To extract the metal, lead (II) sulfide (mineral galena) is roasted in air to form lead (II) oxide (PbO): 2 PbS(s) + 3 O2(g) → 2 PbO(s) + 2 SO2(g) AHrxn = -827.4 kJ Then the lead (II) oxide is reduced with carbon to the metal lead: PbO(s) + C(s) Pb(s) + СО (9) AHrxn = +106.8 kJ a) Use the equations above and Hess's Law to determine the enthalpy of change for the following reaction: PbS(s) + /2 O2(g) + C(s) → Pb(s) + CO (g) SO2(g) ΔΗη [ Select ] kJ (1 mol PbS) b) How much energy (kJ) absorbed (+AHxn) or evolved (-AHpxn) when 400.0 grams of lead (II) sulfide (PbS(s) is converted to lead (Pb)? ΔΗΡη [ Select ] kJ / 400.0 g PbS
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
![Lead (Pb) has been used for centuries. The Romans used it in their plumbing systems - the symbol for
lead (Pb
plumbus). To extract the metal, lead (II) sulfide (mineral galena) is roasted in air to form
lead (II) oxide (PbO):
2 PbS(s) + 3 O2(g)
→ 2 PbO(s) + 2 SO2(g)
AHrxn = -827.4 kJ
Then the lead (II) oxide is reduced with carbon to the metal lead:
PbO(s) + C(s)
Pb(s) +
СО (9)
AHrxn
= +106.8 kJ
a) Use the equations above and Hess's Law to determine the enthalpy of change for the
following reaction:
PbS(s) + /2 O2(g)
+ C(s)
→ Pb(s) + CO
(g)
SO2(g)
ΔΗη
[ Select ]
kJ (1 mol
PbS)
b) How much energy (kJ) absorbed (+AHxn) or evolved (-AHpxn) when 400.0 grams of lead (II) sulfide
(PbS(s) is converted to lead (Pb)?
ΔΗΡη
[ Select ]
kJ / 400.0 g
PbS](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fb99220ad-d702-4943-b904-ec3abe399c73%2F96ef48bf-833c-4d88-b312-b2e8af39f7b3%2Fvhf4vm_processed.png&w=3840&q=75)
An exothermic reaction is the reaction in which energy is evolved in products.
But an endothermic reaction is the reaction in which energy is absorbed in products.
Here some reactions are given , we have to find enthalpy of reaction for the given reaction.
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