4.2 × 10? J/(kg℃)
Calculation formula Q=cm△t
Q represents heat c represents specific heat capacity m represents mass △t represents temperature change < /p>
If heated from 0 degrees to 100 degrees, heat required = 4.2×10? * 1000 * 100 = 420000000J = 116.6666667KW.H
That is, without taking into account the loss, requiring 116.6666667 kilowatt hours of electricity
If sufficiently of firepower is used, what is the highest temperature at which liquid water can be burned?
Electricity costs 5 yuan to boil 100 kilograms of water at 100 degrees. According to the relevant information query, the heat that 100 kilograms of water must absorb to heat to 100 degrees can be calculated according to the endothermic formula Q absorption is equal to 4.2 times 103 times 100 times 100 minus 20 = 33.6 times 106. This heat is absorbed by the electric heater. Provided that consumptionn of electricity is 33.6 times 106 divided by 3.6 times 106, which equals 9.3 degrees. Due to heat loss during heating, the actual required 10 degrees of electricity is 0.5 yuan per. kilowatt hour, so 0.5 times 10 equals 5 yuan.
The boiling point of liquid water is related to pressure. The boiling point of water is 100℃ under standard atmospheric pressure. If we increase the pressure, the boiling point of water will also increase. For example, when the air pressure reaches 10 MPa, the boiling point of water also increases. The boiling point can reach 300℃, and when the pressure exceeds 22.064 MPa, it becomes supercritical water.
We know that it is difficult to cook rice by boiling water in a regular pot on the tray, because when the atmospheric pressure decreases, the boiling point of water also decreases, for example at an altitudeof 1,000 meters. At 4,000 meters, the boiling point of water is only 88℃, the boiling point of water at the top of Mount Everest is only about 70℃. It is best to use a pressure cooker to cook the food at this time.
The pressure inside the pressure cooker is designed to be approximately 1.5 to 1.8 atmospheres, which corresponds to the boiling point of water being 110°C at 117°C. So it is faster to cook food in a pressure cooker. pressure cooker because the temperature inside is higher.
In physics, crystalline substances often come in three forms: solid, liquid, and gas. We use a three-phase diagram to describe the relationship between material shape and pressure. water.
We can see from the image that water is generally divided into three regions: the solid region on top, the liquid region in the middle, and the gas region below. The intersection of the three regions is appeeled. the three phases. Point, the point data of the water three-phase diagram is:
273.16K (0.01℃), 611.73Pa.
Standard atmospheric pressure is 101.3 Kpa. The three-phase diagram of water shows that the solid-liquid boundary point at this time is freezing point 0°C and gas-liquid. the junction point is the boiling point 100°C.
As pressure increases, below 50 MPa (500 atmospheres), the freezing point temperature of water does not change much, but the boiling point of water increases considerably, such as:
( 1 )0.15Mpa, the boiling point of water is 111 ℃;
(2) At 1Mpa, the boiling point of boiling point of water is 180°C
(3) At 5Mpa, the boiling point of water is 264°C
(4) At 10Mpa , the boiling point of water is 311℃;
(5) At 20Mpa, the boiling point of water is 366℃.
In thermal power plants, water must be heated and evaporatedunder high pressure, then the steam drives the turbine to do its work. For subcritical units, the pressure inside the steam drum can reach 16~. 19 MPa and the internal boiling water temperature just above 300℃.
As the pressure increases, the difference between the gaseous and liquid states of water becomes smaller and smaller, until reaching the supercritical point (647K, 22.064 MPa), both do not can no longer be distinguished, except in the solid state region. The water is collectively called supercritical water. For example, in the supercritical unit of a thermal power plant, the main steam pressure reaches 25 MPa and the temperature can reach more than 500 degrees Celsius.
In an underwater crater 5,000 meters deep, the pressure reaches nearly 50 MPa (500 atmospheres). The water near the crater at this time is supercritical water, with a water temperature of up to 450.Celsius degree.
However, water temperature has no upper limit. When the temperature reaches a certain level, the chemical bonds in the water molecules break, forming a plasma state of hydrogen atoms and oxygen atoms. this time the substance has essentially. We can no longer call it water.