1. A gas is confined to a cylinder under constant atmospheric pressure. When 0.49 KJ of heat is added to the gas, it expands and goes 214 J of work on the surroundings. What are the values of ΔH and ΔE for this process? 2. Calcium carbide, CaC2, is the raw materials for the production of acetylene (used in wedding torches). Calcium carbide is produced by reacting calcium oxide with carbon. Carbon monoxide is also produced in this reaction. When one mole of calcium carbide is formed, 464.8 KJ is absorbed.
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.
1. A gas is confined to a cylinder under constant atmospheric pressure. When 0.49 KJ of heat is added to the gas, it expands and goes 214 J of work on the surroundings. What are the values of ΔH and ΔE for this process?
2. Calcium carbide, CaC2, is the raw materials for the production of acetylene (used in wedding torches). Calcium carbide is produced by reacting calcium oxide with carbon. Carbon monoxide is also produced in this reaction. When one mole of calcium carbide is formed, 464.8 KJ is absorbed.
(a) wite a thermochemical equation for this reaction.
(b) Is the reaction exothermic or endothermic?
(c) what is ΔH when 1.00 g of CaC2(s) is formed?
(d) How many grams of carbon must react to produced 3.03x10³ KJ of heat?
3. Calculate ΔH for the decompositiom of one mole of acetylene to its elements in their stable state at 25°C and 1 atm:
C2H2(g) = 2C(s) + H2(g)
Given thermochemical equation;
C2H2(g) +5/2 O2(g) = 2 CO2(g) + H2O(l)
C(s) +O2(g) = CO2(g)
H2(g) +½ O2(g) = H2O(l)
ΔH = -1299.6 kJ
ΔH = -393.5 Kj
ΔH = - 285.8 kj
4. Cite at least three situations relating tothermodynamics and thermochemistry in the context of your real life day-to-day living.
- 5. Some minerals are the nutrients that exist in tje body and some could be found naturally in the environment. As a student, how can you help in conserving and preserving the natural sources of these minerals like calcium and potassium?
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20
many gram
(a) Write a thermochemical equation for this reaction.
(b) Is the reaction exothermic or endothermic?
(c) What is AH when 1.00 g of CaCa(s) is formed?
(aj How many grams of carbon must react to produce 3.03x10 kJ of heat?
3. Calculate AH for the decomposition of one mole of acetylene to its elements in their stable
state at 25°C and 1 atm:
C2H2(g)2C(s) + H2(g)
Given thermochemical equations:
C2Halg) + 5/2 Odg) → 2 CO:{g) + H2O(}
C(s) + O2(g) - CO2(g)
H2(g) + Oz(g) → H2O(1)
AH = -1299.6 kJ
AH = -393.5 kJ
AH = -285.8 kJ
)
Reflection: Cite at least three situations relating to thermodynamics and thermochemistry in the
context of your real-life day-to-day living. Write your responses on a separate sheet. De guided
with the following rubric:
Reflection Rubric
Practical application is scientifically explained consistent to the
concepts, and has no misconception.
Practical application is scientifically explained consistent to the
concept, but with minimal misconception.
Practical application is explained consistent to the concepts, but
with misconceptions.
No discussion provided.
3.
1](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff62dcb24-e2a8-4f22-97e2-eacb89c34968%2F1e8cb6cd-419e-4bd0-b123-072895552446%2Fmeancv_processed.jpeg&w=3840&q=75)
![C. Lost to the surroundings when one mole of hydrogen is used up in the reaction.
d. Lost to the surroundings when three moles of hydrogen are used up in the reaction.
20
An oxyacetylene torch is a tool that mixes and burns oxygen and acetylene to produce an
extremely hot flame. This tool is used to cut steel or weld iron and other metals. The
temperature of the film can reach 3,480°C. The burning of acetylene is given by the
thermochemical equation:
5.
C2H2 (g) + 3/2 O2 (g)
CO2 (g) + H2O (1)
AH = - 1301.1 kJ
%3D
What is the AH for the reaction below?
2 CO2(g) + 2 H2O(1)
2 C2H2(g)
+ 3 O2(g)
c. AH = 2602.2 kJ
d. AH = - 2602.2 kJ
a. AH = 1301.1 kJ
%3D
%3D
b. AH = - 1301.1 kJ
%3D
Activity 2 - Energize your mind!
Learning objectives:
1. Calculate heat, work and energy change using the first law of thermodynamics;
2. Use the thermochemical equation to calculate the heat evolved or absorbed when a given
amount of reactant is converted to products;
3. Calculate the change in enthalpy of a reaction using Hess's Law.
What you need: Paper, pen, calculator
What to do: Answer as directed. Show your solution for necessary calculations. Write your
answers on a separate sheet of paper.
1. A gas is confined to a cylinder under constant atmospheric pressure. When 0.49 kJ of heat
is added to the gas, it expands and does 214 J of work on the surroundings. What are the
values of AH and AE for this process?
2. Calcium carbide, CaC2, is the raw material for the production of acetylene (used in welding
torches). Calcium carbide is produced by reacting calcium oxide with carbon. Carbon
monoxide is also produced in this reaction. When one mole of calcium carbide is formed,
464.8 kJ is absorbed.
Supply the needed answer for the following:
Author: CRISTOBERT C. AYATON
School/Station: LIANGA NATIONAL COMPREHENSIVE HIGH SCHOOL - LIANGA I DISTRICT
Division: SURIGAO DEL SUR](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff62dcb24-e2a8-4f22-97e2-eacb89c34968%2F1e8cb6cd-419e-4bd0-b123-072895552446%2F5nfo0s_processed.jpeg&w=3840&q=75)
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