Heat II

Question 1

The amount of heat required to raise the temperature of 1kg of a substance by 1 K or 1ºC.

Answer 1

specific heat capacity

Question 2

Human tissue heat capacity is approximately ___ that of water.

Answer 2

0.85

Question 3

Specific heat capacity of water is:

Answer 3

4.18 kJ / (kg * ºC)

Question 4

The amount of heat required to raise the temperature of a given object by 1 Kelvin.

Answer 4

heat capacity

Question 5

The tissue specific heat capacities can be approximated to a mean value of ____ kJ/(kg * ºC)

Answer 5

3.5 kJ/(kg * ºC)

Question 6

The specific heat of blood is:

Answer 6

3.6 kJ / (kg * ºC)

Question 7

1 calorie = ____ Joule

Answer 7

4.18 Joule

Question 8

Heat capacity of the body is:

Answer 8

3.5 kJ / (kg * ºC) * 70 kg = 245 kJ / ºC

Question 9

Heat required to warm 2 liters of blood from 5 - 35ºC

• in kJ
• Cal
• ºC

Answer 9

= 2kg * 3.55 kJ / (kg * C) * (35-5)ºC

=213 kJ

=50.96 Cal

213 kJ / (245 kJ * C) = 0.869 C

Question 10

4 liters of fluid at 21ºC will only change temperature by about ___

Answer 10

1ºC

Question 11

If giving 2 liters fluid at 4ºC, drops temperature by approximately ____

Answer 11

1ºC

like bank blood

Question 12

4 liters of fluid at 4ºC will drop core temperature by approximately ____.

Answer 12

2ºC

Question 13

Specific heat of air (2) =

Answer 13

0.29 cal / (L*^oC)

or 1.2 J / (L*^oC)

Question 14

Heat loss from warming inspired air

if 7 liter/min

14ºC

in Watts?

Answer 14

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)

Question 15

Specific latent heat of water at 100ºC =

Answer 15

2.26 MJ/kg

Question 16

Specific latent heat of water at 37ºC is:

MJ / kg

cal / gram

Answer 16

2.42 MJ / kg

–> 578.98 cal/gram

Question 17

If you raise the body temperature water to 100ºC:

Answer 17

540.67 cal/gram + (100 - 37) = 603 cal/gram

Question 18

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 ____.

Answer 18

36.5

liquid

Question 19

Everything has a vapor pressure. There is an energy of vaporization. When vaporizers lose energy to turn liquids into gas, become _____.

Answer 19

cooler

Question 20

Change of pressure in a nitrous oxide cylinder if emptied at 5 liters/minute. What occurs when flow is turned off?

Answer 20

Pressure is restored if the flow turned off

Question 21

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.

Answer 21

7 bar

Dewar flask

Question 22

By the time gases reach the trachea, their humidity is about ___ mg water vapor per liter of gas.

Answer 22

34 mg

This water comes from vaporization from the mucosa of the respiratory tract.

Question 23

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?

Answer 23

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

Question 24

At 20ºC, the latent heat of vaporization of nitrous oxide is:

Answer 24

10 MJ / kg