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Why the kinetic energy of the molecules falls during cooling?
The molecules with a higher kinetic energy overcome the intermolecular forces of attraction and break away from the surface of the liquid and escape into the atmosphere as vapor. The molecules that remain will therefore have a lower kinetic energy and will, logically, have a lower temperature.
Why more serious burns are caused by steam than water at same temperature?
The heat content of 1 gram of steam of 100oC is much higher than that of 1 gram of 100oC, the extra comes from condensation heat (energy).
Why would a burn by 1 gram of steam do more damage than a burn caused by 1 gram of water at the same temperature?
It requires energy to change the state of water from liquid (water) to gas (steam), so even thought they are at the same temperature, the same amount (1 gram) of steam holds more energy than 1 gram of liquid water at the same temperature. If the steam came in contact with a person's skin, it would lose energy, some of it absorbed by the person (causing damage), and it will not reduce temperature until it is condensed, because all of the energy lost was due to the state change.
Why the specific heat capacity of water becomes infinity when boiling water changes into steam?
Specific heat is usually defined as the amount of energy that must be added to change the temperature. Another way to define it is the ratio between the amount of energy added and the change in temperature E/m·T(with units like joules/gram·°C) When water is at the saturation point and energy is added to it, instead of increasing in temperature, the water changes phase from liquid to gas. If you put the numbers back into the definition you get something like: 1 joule added to 1 gram of water yields a change of 0 °C so Cp = 1/1∙0 = ∞.
Why does the volume of the water vapor increase and the mass remain constant When 1 gram of water is evaporated?
Mass is mass. It is constant. Changing water from liquid to gas does not change the mass, it only changes the density, which is mass per volume. Look at it another way - in gaseous form, the same mass of water has the same number of molecules of water - but those molecules are simply further apart.
At which temperature would the molecules in a one gram sample of water have at the lowest average kinetic energy?
5 k
Why does it take 80 calories to convert 1 gram of water to 1 gram of steam?
Water molecules attract each other; energy is required to overcome that attraction. In other words, the change of phase implies a change in potential energy.
Why 1 gram of steam has a volume about 1000 times the volume of one gram ofwater?
Simply because - due to the addition of heat, the water molecules in steam are further apart than those in cold water.
What is the kinetic energy of a 8.47E plus 4 gram person moving at a velocity of 24.9 meters per second?
The kinetic energy of the person can be calculated using the formula: KE = 0.5 * mass * velocity^2. First convert the mass to kilograms (1 gram = 0.001 kg), then plug in the values to find the kinetic energy. The result will be in Joules.
Steam at 100 C contains the same amount of heat energy per gram as liquid water at 100 C?
For a given mass, steam will have more energy than water. The difference is called the 'heat of vaporization'. One thing to be carefuls about, of course, is that a given mass of steam will occupy much more volume than the same mass of water.
Why the kinetic energy of the molecules falls during cooling?
The molecules with a higher kinetic energy overcome the intermolecular forces of attraction and break away from the surface of the liquid and escape into the atmosphere as vapor. The molecules that remain will therefore have a lower kinetic energy and will, logically, have a lower temperature.
Why more serious burns are caused by steam than water at same temperature?
The heat content of 1 gram of steam of 100oC is much higher than that of 1 gram of 100oC, the extra comes from condensation heat (energy).
Why would a burn by 1 gram of steam do more damage than a burn caused by 1 gram of water at the same temperature?
It requires energy to change the state of water from liquid (water) to gas (steam), so even thought they are at the same temperature, the same amount (1 gram) of steam holds more energy than 1 gram of liquid water at the same temperature. If the steam came in contact with a person's skin, it would lose energy, some of it absorbed by the person (causing damage), and it will not reduce temperature until it is condensed, because all of the energy lost was due to the state change.
Where is energy in food stored in?
Energy in food is stored in three types of molecules. Carbohydrates and proteins can store 4 kCal per gram. Fats (or triglycerides) can store up to 9 kCal per gram.
What molecules can produce more energy per gram than sugars and are used for storing in animals?
lipids
Why does melting ice require much less energy than boiling the same mass of water?
Because Water's latent heat of fusion is much less than its latent heat of vaporization. In English: It takes less energy to change a gram of ice at 0°C into a gram of water at the same temperature than it takes to change a gram of water at 100°C into a gram of steam at the same temperature.
Why the specific heat capacity of water becomes infinity when boiling water changes into steam?
Specific heat is usually defined as the amount of energy that must be added to change the temperature. Another way to define it is the ratio between the amount of energy added and the change in temperature E/m·T(with units like joules/gram·°C) When water is at the saturation point and energy is added to it, instead of increasing in temperature, the water changes phase from liquid to gas. If you put the numbers back into the definition you get something like: 1 joule added to 1 gram of water yields a change of 0 °C so Cp = 1/1∙0 = ∞.
