Flashcards in Physics Quiz 7(Thermodynamics) Deck (72):
What is latent heat?
When a substance changes from one state to anther, latent heat is added or released in the process.
Ice--->Vapor(latent heat of sublimation is added)
Vapor---->Ice(latent heat of deposition is released)
The amount of heat required to change 1 gram of ice at 0'C to 1 gram of water at 0'C is 80 calories. What is this called?
Heat of fusion of water
To change 1 gram of water at 100'C to water vapor at 100'C requires 540 calories of heat. What is this called?
Heat of vaporization
What is the process called by which water changes to its gaseous state(water vapor)?
Boiling or evaporating
How many calories of heat is added for ice to melt to water?
How many calories of heat are added for ice to evaporate from water to vapor?
In the warming process between 0'C and 100'C how many calories are added?
How many calories of heat are removed for water vapor to cool to the liquid form of water?
How many calories of heat are removed as water cools from 100'C to 0'C?
How many calories of heat are removed for water to freeze to a solid form of ice?
What is Sublimation, and what is an example of it?
Sublimation is the change of a solid substance directly to a vapor without first passing through the liquid state. Two examples of this is iodine and Dry Ice(solid carbon dioxide which sublimes at -78.5'C)
What is Deposition and what is an example of it?
Deposition is a process where a gas changes phase and turns directly into a solid without first passing through the liquid phase. One common example is snow that is formed in the clouds. Water vapor changes directly to ice without first becoming liquid.
What is the opposite of Sublimation?
For molecules in water, what does average kinetic energy depend upon?
What describes the attractive and repulsive forces between water molecules that make their motion quite random?
This is known as Brownian motion
As greater kinetic energy(higher temperatures) is applied to water molecules what happens?
They move apart ultimately the greater kinetic energy allows them to escape individually as a vapor.
As smaller kinetic energy(lower temperatures) is applied to water molecules what happens?
They move closer together becoming a solid(ice).
What is the difference between heat versus temperature?
Temperatures can be viewed as an arbitrary numerical ranking of "hotness" or "coldness".
Heat can be viewed as energy that is transferred as a result of a temperature difference(it is an energy flow).
*When two bodies of unequal temperatures are brought into contact, a flow of heat occurs from the hot object to the cold object until the two temperatures become equal.*
What is the quantitative measurement of of thermal energy?
What is referred to as thermal energy?
What is the equation converting Celsius to Kelvin?
K='C + 273
What is the equation converting Celsius to degree Fahrenheit?
What is the equation converting Fahrenheit to degree Celsius?
What is the numerical representation of standard temperature?
273K or 0'C
What is another word to describe heat?
Heat loss(energy loss) is unidirectional from what to what?
higher concentration to a lower concentration. Hotter to less hot.
The human body is a system that contains energy and there is a constant exchange of heat with the environment from high concentration to lower concentration.
What is a word used to describe the protective mechanisms such as vasoconstriction of peripheral vessels that slows heat loss from our bodes and vasodilation of peripheral vessels that promotes heats loss when we are exposed to a warmer environment?
A patient's core temp can quickly drop by the vasodilating actions of anesthetics, when is the greatest decrease seen?
the greatest decrease is in the first hour
Blood flow to our body's surface encourages heat loss by four primary processes, what are they?
Of the 4 primary process by which the body looses heat, what are the two that are most responsible for heat loss of the body?
What is the term used to describe the transfer of energy between 2 objects that are not in direct contact but that differ in temperature?
Radiation transfers heat energy from our warm bodies to the less warm OR environment.
*Warm body to Cold room*
What is the most significant mechanism of heat loss by our bodies, especially by patients under anesthesia?
What is one substantial way radiant heat loss can be reduced?
increasing the room temperature so the temperature gradient between patient and environment in the OR is less.
What describes the process of creating air currents by heat?
convection(wind chill current)
How does the human body loose heat through convection?
The body transfers kinetic energy to air molecules on the surface of our skin. These heated air molecules rise and are replaced by colder ones that have less kinetic energy. The body releases more kinetic energy which heats these molecules up and they rise and leave being replaced by colder ones again.
What is a less important process of heat loss in which moisture evaporates from the patient's skin as well as through the respiratory tract(exhaled water vapor)?
The process of evaporation requires energy as it causes a phase change from liquid to gas.
What are three ways in which surgical patients loose heat by evaporation?
2. those surgically prepped with liquids
3. through the process of breathing(most significant in pediatrics)
What are two things that can be done to limit heat loss through the evaporation of pulmonary water?
1. use lower gas flows
2. use an inline humidifying apparatus
Through which route do burn patients loose the highest percentage of body heat?
What describes the transfer of heat by physically touching a less warm object? It is the heat exchange that occurs from direct contact from high concentration to a lower concentration.
What is an example of the conduction of heat?
Ice cube in the hand, the sensation of cold is the direct loss of heat from your hand to the ice cubes. Cold is not transferred to your hand; heat is transferred to the ice cubes.
Through which route do patients on cold OR tables loose their body heat?
Most significant in pediatric patients, the use of warming blankets on OR tables stops or reverses this heat transfer.
Heat loss form patients is primarily due to ?
radiation of in fared electromagnetic radiation
What is the second largest method of heat loss in anesthetized patients?
What are two other process that patients experience heat loss but to a lesser extent?
evaporation and conduction
Most concerning in pediatrics
Heat is lost from the body by four process, rank these routes from those that contribute the most to those that contribute the least to heat loss.
Approximately what percent of total heat loss from the body normally occurs by radiation and convection combined?
70%(40% radiation and 30% convection)
What are five methods that can be used to limit heat loss in the operating room?
1. warming the OR
2. using forced warm air devices
3. using lower gas flow rates
4. using humidification systems
5. covering and insulating patients with plastic/blankets
What is vaporization and what does it require?
It is the process of converting liquids or solids into vapors and it requires energy.
What is the term used to describe the energy needed to transform a given amount of liquid into a gas and is measured in calories or kilojoules.
Latent heat of vaporization
The temperature at which the bulk of a liquid at a given pressure converts to a vapor is call the?
It's boiling point
The temp of a liquid will not rise above its boiling point, instead the energy is used to transform the liquid into a gas.
Heating a liquid to its boiling point increases the kinetic energy of the liquid's molecules. As gas molecules escape the liquid, they exert a pressure known as ___ ___, measure in millimeters of mercury(mmHg).
What is the vapor pressure of sevoflurane @ 20 'C?
What is the vapor pressure of enflurane @ 20 'C?
What is the vapor pressure of isoflurane @ 20 'C?
What is the vapor pressure of halothane @ 20 'C?
What is the vapor pressure of desflurane @ 20 'C?
Is vapor pressure a function of volume, temperature or pressure?
Vapor pressure is a unique characteristic of liquid that depend solely on temperature.
Does saturated vapor pressure change with the altitude?
Vapor pressure only changes with temperature.
What is the boiling point of a liquid?
The boiling point of a liquid is defined as the temperature at which the vapor pressure of the liquid equals atmospheric pressure.
What volatile agent will boil in the mountains? Why?
Desflurane will boil in the mountains because its vapor pressure(669 mmHg) will be greater than the barometric pressure.
What happens when the vapor pressure of a liquid exceeds the total pressure in the gas phase?
When the vapor pressure of a liquid exceeds the total(atmospheric) pressure, the liquid boils.
If a higher vapor pressure agent is placed in a vaporizer designed for a lower pressure agent, the concentration of agent delivered to the patient will be _____ than the dial setting.
If a lower vapor pressure agent is placed in a vaporizer designed for a higher vapor pressure agent, the concentration of agent delivered to the patient will be ____ than the dial setting.
What happens to the temperature of a liquid as vaporization occurs?
Since vaporization requires energy, the temperature of the liquid decreases as vaporization proceeds. Energy flows from the warmer area(surroundings) to the cooler area(liquid)-this flow of thermal energy is called heat.
What is heat of vaporization?
The phase change from the liquid state to the gaseous state called vaporization. It takes energy for molecules to break away and enter the gaseous phase. A liquid's heat of vaporization is the number of calories necessary to convert 1 ml liquid into a vapor.
What is latent heat of vaporization?
The latent heat of vaporization is more precisely defined as the number of calories required to change 1 gram of liquid into vapor without a temperature change.
What will happen to the gas concentration delivered to the patient is enflurane or sevoflurane is placed in an isoflurane vaporizer? why?
The delivered concentration of enflurane or sevoflurane will be less than expected by the dial setting, because they have a lower vapor pressure than isoflurane.
What will happen to the concentration delivered to the patient if enflurane or sevoflurane is placed in a halothane vaporizer and why?
The delivered concentration of enflurane will be less than expected by the dial setting, because enflurane and sevoflurane have lower vapor pressures than halothane.
What will happen to the concentration delivered to the patient if halothane is placed in an enflurane or sevoflurane vaporizer? why?
The delivered concentration of halothane will be greater than expected by the dial setting, because halothane has a higher vapor pressure than either enflurane or sevoflurane.
What will happen to the concentration delivered to the patient if isoflurane is placed in an enflurane or sevoflurane vaporizer? why?
The delivered concentration of isoflurane will be greater than expected by the dial setting, because isoflurane has a higher vapor pressure than either enflurane or sevoflurane.