Heat II Flashcards
The amount of heat required to raise the temperature of 1kg of a substance by 1 K or 1ºC.
specific heat capacity
Human tissue heat capacity is approximately ___ that of water.
0.85
Specific heat capacity of water is:
4.18 kJ / (kg * ºC)
The amount of heat required to raise the temperature of a given object by 1 Kelvin.
heat capacity
The tissue specific heat capacities can be approximated to a mean value of ____ kJ/(kg * ºC)
3.5 kJ/(kg * ºC)
The specific heat of blood is:
3.6 kJ / (kg * ºC)
1 calorie = ____ Joule
4.18 Joule
Heat capacity of the body is:
3.5 kJ / (kg * ºC) * 70 kg = 245 kJ / ºC
Heat required to warm 2 liters of blood from 5 - 35ºC
- in kJ
- Cal
- ºC
= 2kg * 3.55 kJ / (kg * C) * (35-5)ºC
=213 kJ
=50.96 Cal
213 kJ / (245 kJ * C) = 0.869 C
4 liters of fluid at 21ºC will only change temperature by about ___
1ºC
If giving 2 liters fluid at 4ºC, drops temperature by approximately ____
1ºC
like bank blood
4 liters of fluid at 4ºC will drop core temperature by approximately ____.
2ºC
Specific heat of air (2) =
0.29 cal / (L*oC)
or 1.2 J / (L*oC)
Heat loss from warming inspired air
if 7 liter/min
14ºC
in Watts?
flow * specific heat capacity * temperature rise
7 liter/min * 1.2 J/liter*C * 14ºC
118 J/min
1.97 W (1 W = J/s)
Specific latent heat of water at 100ºC =
2.26 MJ/kg
Specific latent heat of water at 37ºC is:
MJ / kg
cal / gram
2.42 MJ / kg
–> 578.98 cal/gram
If you raise the body temperature water to 100ºC:
540.67 cal/gram + (100 - 37) = 603 cal/gram
The temperature at which the latent heat of vaporization of nitrous oxide becomes zero corresponds to its critical temperature of ___ºC.
At this temperature, the substance changes spontaneously from liquid to vapour without the supply of any external energy. Above this critical temperature the substance cannot exist as a ____.
36.5
liquid
Everything has a vapor pressure. There is an energy of vaporization. When vaporizers lose energy to turn liquids into gas, become _____.
cooler
Change of pressure in a nitrous oxide cylinder if emptied at 5 liters/minute. What occurs when flow is turned off?
Pressure is restored if the flow turned off
The liquid in a storage vessel, called a ____ ____ is at a temperature of around -160C and must be kept in a special storage vessel resembling a gigantic vacuum flask to maintain it at this low temperature. Normally the pressure inside the vessel is set to about_____, this being the vapour pressure of the oxygen at this temperature.
7 bar
Dewar flask
By the time gases reach the trachea, their humidity is about ___ mg water vapor per liter of gas.
34 mg
This water comes from vaporization from the mucosa of the respiratory tract.
Consider a person breathing completely dry gases at 7 liters/min.
Humidity in the upper trachea is _____ mg/liter.
Total water required to humidify inspired gas= g/min
Total latent heat needed? J/min
Watts?
34 mg / liter
7 liters/min * 34 mg/liter = 0.238 g/min
= 2.42 MJ / kg * 0.000238 kg/min
=576 J/min
=9.6 Watt
At 20ºC, the latent heat of vaporization of nitrous oxide is:
10 MJ / kg
