6. Given 2CuO (s) → 2Cu (s) + O₂ (g) AH = 314.6 kJ a. Determine the heat of formation of CuO (s). b. Calculate AH for the formation of 13.58 g of CuO.
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.
![# Thermochemical Reactions and Calculations
## Problem 5: Strontium Metal Reaction
### Description:
Strontium metal combines with graphite (C) and oxygen gas to produce strontium carbonate. The formation of one mole of SrCO₃ releases 1.220 x 10³ kJ of heat.
### Questions:
a. Write a balanced thermochemical equation for the reaction resulting in one mole of SrCO₃.
b. What is ΔH when 10.0 g of strontium reacts with excess graphite and oxygen?
c. What mass of SrCO₃ forms when 2355 kJ of heat are also formed?
## Problem 6: Decomposition of Copper Oxide
### Given Reaction:
\[ 2CuO(s) \rightarrow 2Cu(s) + O₂(g) \]
### Enthalpy:
\[ \Delta H = 314.6 \, \text{kJ} \]
### Questions:
a. Determine the heat of formation of CuO(s).
b. Calculate ΔH for the formation of 13.58 g of CuO.
## Problem 7: Decomposition of Limestone (CaCO₃)
### Description:
Limestone (CaCO₃) decomposes when subjected to a temperature of 900⁰C in a kiln, resulting in solid calcium oxide and carbon dioxide gas.
### Questions:
a. Write a balanced chemical equation for this reaction.
b. Determine ΔH for the reaction using the handout of standard heats of formation.
c. How much heat is evolved or absorbed when one gram of limestone decomposes at 900⁰C?
#### Calculations:
- For 1 g CaCO₃:
\[ \Delta H = \frac{131597}{100.09}\, \text{J/g} = 1315.97 \, \text{J} \]
## Problem 8: Energy Change for Steam Conversion
### Description:
Calculate the energy change for steam condensation and heating/cooling.
### Questions:
1. How much energy is released when 52.3 g of steam at 136.5⁰C cools and condenses to form water at 93.2⁰C?
\[ = 123.52 \, \text{kJ} \]
2. How much energy is needed to heat a 42.3 g sample of ice at -35.7](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F7c430cc2-4097-4d45-9871-f052d1dcc428%2F8ee23fbd-9099-4928-86ca-896a452a97c3%2Fwnkdhil_processed.jpeg&w=3840&q=75)
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