8. Thermochemistry

First Law of Thermodynamics

First Law of Thermodynamics -

What is the First Law of Thermodynamics?

(a) According to the first law of thermodynamics, what
quantity is conserved?

A gas is confined to a cylinder fitted with a piston and an
electrical heater, as shown here:
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/3517445e59da25b2-1660743670764.jpg" alt="" />
Suppose that current is supplied to the heater so that 100 J of
energy is added. Consider two different situations. In case (1)
the piston is allowed to move as the energy is added. In case
(2) the piston is fixed so that it cannot move. (b) Identify the sign (positive, negative,
or zero) of q and w in each case?

A standard air conditioner involves a refrigerant that is typically now a fluorinated hydrocarbon, such as CH2F2. An air-conditioner refrigerant has the property that it readily vaporizes at atmospheric pressure and is easily compressed to its liquid phase under increased pressure. The operation of an air conditioner can be thought of as a closed system made up of the refrigerant going through the two stages shown here (the air circulation is not shown in this diagram). 
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/74277c34c921643e-1665500526888.jpg" alt="" /> 
During expansion, the liquid refrigerant is released into an expansion chamber at low pressure, where it vaporizes. The vapor then undergoes compression at high pressure back to its liquid phase in a compression chamber. (c) In a central air-conditioning system, one chamber is inside the home and the other is outside. Which chamber is where, and why?

A system goes from state 1 to state 2 and back to state 1. (c) Suppose the changes in state are reversible processes. Is the work done by the system upon going from state 1 to state 2 the same or different as compared to that upon going from state 2 back to state 1?

In a thermodynamic study, a scientist focuses on the properties
of a solution in an apparatus as illustrated. A solution is
continuously flowing into the apparatus at the top and out at
the bottom, such that the amount of solution in the apparatus
is constant with time. (b) If the inlet
and outlet were closed, what type of system would it be
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/a701c66f517d89a8-1661428159862.jpg" alt="" />

First law of Thermodynamics | Physics

Redraw the following diagram to represent the situation (a) when work has been gained by the system and

Consider a process in which an ideal gas changes from state 1 to state 2 in such a way that its temperature changes from 300 K to 200 K. (b) Is this process isothermal?

The First Law of Thermodynamics

Consider a system consisting of the following apparatus, in
which gas is confined in one flask and there is a vacuum in
the other flask. The flasks are separated by a valve. Assume
that the flasks are perfectly insulated and will not allow the
flow of heat into or out of the flasks to the surroundings.
When the valve is opened, gas flows from the filled flask to
the evacuated one. (a) Is work performed during the expansion
of the gas? (b) Why or why not?
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/7aaff277836d0dff-1664297311947.jpg" alt="" />

Imagine that you are climbing a mountain. (a) Is the
distance you travel to the top a state function?

Identify each energy exchange as primarily heat or work and
determine whether the sign of ΔE is positive or negative for the
system.
Identify each energy exchange as primarily heat or work.
a. A rolling billiard ball collides with another billiard ball. The
first billiard ball (defined as the system) stops rolling after the
collision.
b. A book falls to the floor. (The book is the system).
c. A father pushes his daughter on a swing. (The daughter and
the swing are the system).
Identify each energy exchange as primarily heat or work.

Consider the two diagrams that follow. (d) Would
similar relationships hold for the work involved in each
process?
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/79690c11624a6c18-1661432221517.jpg" alt="" />

What is the difference between heat and temperature?

(d) Does the amount of work that a system can do on its surroundings depend on the path of the process?

(a) Which of the thermodynamic quantities T, E, q, w, and S are state functions? (b) Which depend on the path taken from one state to another?

(c) Is the volume of a system a state function? Why or
why not?

Imagine a reaction that results in a change in both volume and temperature:  (a) Hasanyworkbeendone?Ifso,isitssignpositiveornegative?

What are the signs of q and w when a system loses heat while doing work on the surroundings?

First Law of Thermodynamics Example 1

The air bags that provide protection in automobiles in the
event of an accident expand because of a rapid chemical reaction.
From the viewpoint of the chemical reactants as the
system, what do you expect for the signs of q and w in this
process?

A room-temperature balloon filled with air is placed in the freezer and the balloon contracts. What is the sign of q and w for the air inside the balloon? (LO 9.4)
(a) q = +, w = - (b) q = +, w = + (c) q = -, w = - (d) q = -, w = +

Which of the following are state functions, and which are not? (a) The temperature of an ice cube
(b) The volume of an aerosol can
(c) The amount of time required for Paula Radcliffe to run
her world-record marathon: 2:15:25

Consider a process in which an ideal gas changes from state 1 to state 2 in such a way that its temperature changes from 300 K to 200 K. (a) Does the temperature change depend on whether the process is reversible or irreversible?

 Energy is neither lost nor gained by an object. 

 Consider that the total energy in the universe is constant. 

 The energy lost by a system is gained by the surroundings. 

 Correct, the total amount of energy in the universe is constant. 

 The energy gained by a system is also gained by the surroundings. 

 Consider the meaning of the word conserved. 

 Which is a correct statement of the law of conservation of energy? 

First Law of Thermodynamics [year-1]

FIRST LAW OF THERMODYNAMICS | Easy and Short

In the accompanying cylinder diagram, a chemical process
occurs at constant temperature and pressure. (a) Is the sign
of w indicated by this change positive or negative?

Imagine that you are climbing a mountain. (b) Is the
change in elevation between your base camp and the peak
a state function?

The First Law of Thermodynamics: Internal Energy, Heat, and Work

Heat is the flow of thermal energy while work is the movement of reacting molecules.

In a thermodynamic study, a scientist focuses on the properties
of a solution in an apparatus as illustrated. A solution is
continuously flowing into the apparatus at the top and out at
the bottom, such that the amount of solution in the apparatus
is constant with time. (a) Is the solution in the apparatus
a closed system, open system, or isolated system? 
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/65f03dc54dd08176-1660745153295.jpg" alt="" />

Understanding the First Law of Thermodynamics

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1. Intro to General Chemistry

2. Atoms & Elements

3. Chemical Reactions

4. BONUS: Lab Techniques and Procedures

5. BONUS: Mathematical Operations and Functions

6. Chemical Quantities & Aqueous Reactions

7. Gases

9. Quantum Mechanics

10. Periodic Properties of the Elements

11. Bonding & Molecular Structure

12. Molecular Shapes & Valence Bond Theory

13. Liquids, Solids & Intermolecular Forces

14. Solutions

15. Chemical Kinetics

16. Chemical Equilibrium

17. Acid and Base Equilibrium

18. Aqueous Equilibrium

19. Chemical Thermodynamics

20. Electrochemistry

21. Nuclear Chemistry

22. Organic Chemistry

23. Chemistry of the Nonmetals

24. Transition Metals and Coordination Compounds

[BOOK CHEM] Clutch Version

Hess's Law

Hess's Law involves the use of partial reactions in the determination of the overall enthalpy of reaction.

Nature of Energy

Thermochemistry is the study of matter and energy associated with chemical reactions or physical changes.&nbsp;

Endothermic & Exothermic Reactions

Endothermic and Exothermic Reactions involve the absorbing and releasing of thermal energy respectively.&nbsp;&nbsp;

Heat Capacity

Heat Capacity is the amount of heat required to change the temperature of a substance.&nbsp;

Thermochemical Equations

Thermochemical Equations&nbsp;involve a balanced chemical equation with a given enthalpy value.

Internal Energy

The Internal Energy of a system is the total energy from all forms of kinetic and potential energy.&nbsp;

Kinetic & Potential Energy

Mechanical Energy is the energy associated with an object's velocity (Kinetic Energy) and its position (Potential Energy).&nbsp;

Formation Equations

Formation Equations involve the standard states of elements combining to form 1 mole of product.

Enthalpy of Formation

The Enthalpy of Formation for an element is a key component in determining the enthalpy of reaction.&nbsp;

Thermal Equilibrium

Thermal Equilibrium involves two substances that are in physical contact reaching the same final temperature over time.&nbsp;

Constant-Pressure Calorimetry

Constant-Pressure Calorimetry uses a coffee cup calorimeter to determine the heat transfers occurring in a liquid solution.

Constant-Volume Calorimetry

Constant-Volume Calorimetry uses a bomb calorimeter and a combustion reaction to determine its enthalpy of reaction.&nbsp;

The First Law of Thermodynamics states that energy cannot be created nor destroyed, but instead is transferred.&nbsp;