Everyone knows that water can be in nature in three states of aggregation - solid, liquid and gaseous. During melting, solid ice transforms into liquid, and upon further heating, the liquid evaporates, forming water vapor. What are the conditions for melting, crystallization, evaporation and condensation of water? At what temperature does the ice melt or steam form? We will talk about this in this article.
Water on earth
This is not to say that water vapor and ice are rare in everyday life. However, the most common is precisely the liquid state - ordinary water. Experts have found that on our planet there are more than 1 billion cubic kilometers of water. However, no more than 3 million km 3 of water belongs to fresh water bodies. A sufficiently large amount of fresh water “rests” in glaciers (about 30 million cubic kilometers). However, to melt the ice of such huge blocks is far from easy. The rest of the water is salty, belonging to the seas of the oceans.
Water surrounds modern man everywhere, during most daily procedures. Many people believe that water reserves are inexhaustible, and humanity can always use the resources of the earth’s hydrosphere. However, this is not the case. The water resources of our planet are gradually depleted, and after several hundred years of fresh water on Earth may not remain at all. Therefore, absolutely every person needs to be careful about fresh water and save it. After all, even in our time there are states in which water supplies are catastrophically small.
Water properties
Before talking about the melting temperature of ice, it is worth considering the basic properties of this unique liquid.
So, the following properties are inherent in water:
- Lack of color.
- Lack of smell.
- Lack of taste (however, quality drinking water tastes good).
- Transparency.
- Fluidity.
- The ability to dissolve various substances (e.g. salts, alkalis, etc.).
- Water does not have its own permanent shape and is able to take the form of a vessel into which it falls.
- The ability to be cleaned by filtration.
- When heated, the water expands, and when cooled, it contracts.
- Water can evaporate, turning into steam, and freeze to form crystalline ice.
This list shows the basic properties of water. Now we will understand what are the features of the solid state of aggregation of this substance, and at what temperature the ice melts.
Snow and ice
Ice is a solid crystalline substance that has a rather unstable structure. It, like water, is transparent, has no color and odor. Ice also has properties such as brittleness and slippery; It is cold to the touch.
Snow also represents frozen water, but it has a loose structure and is white in color. It is snow that falls every year in most countries of the world.
Both snow and ice are extremely volatile substances. To melt the ice, you do not need to make much effort. When does it begin to melt?
Ice melting
In nature, hard ice only exists at temperatures of 0 ° C and below. If the ambient temperature rises and becomes more than 0 ° C, the ice begins to melt.
At ice melting temperature, at 0 ° C, another process occurs - freezing, or crystallization, of liquid water.
This process can be observed by all residents of the temperate continental climate. In winter, when the outside temperature drops below 0 ° C, often enough snow falls that does not melt. And the liquid water that was on the streets freezes, turning into solid snow or ice. In the spring, you can see the reverse process. The ambient temperature rises, so ice and snow melt, forming numerous puddles and mud, which can be considered the only minus of spring warming.
Thus, we can conclude that, at what temperature the ice begins to melt, at the same temperature, the process of freezing water begins.
Quantity of heat
In a science such as physics, the concept of the amount of heat is often used. This value shows the amount of energy required for heating, melting, crystallizing, boiling, evaporating or condensing various substances. Moreover, each of these processes has its own characteristics. Let's talk about how much heat is required for heating ice under normal conditions.
To heat the ice, you must first melt it. This requires the amount of heat needed to melt the solid. Heat is equal to the product of the mass of ice and the specific heat of its melting (330-345 thousand Joules / kg) and is expressed in Joules. Suppose we are given 2 kg of hard ice. Thus, in order to melt it, we need: 2 kg * 340 kJ / kg = 680 kJ.
After that, we need to heat the formed water. The amount of heat for this process will be a little more difficult to calculate. To do this, you need to know the initial and final temperature of the heated water.
So, let's say that we need to heat the water resulting from the melting of ice at 50 ° C. That is, the difference between the initial and final temperature = 50 ° C (initial water temperature - 0 ° C). Then you should multiply the temperature difference by the mass of water and its specific heat, which is 4,200 J * kg / ° C. That is, the amount of heat required to heat the water = 2 kg * 50 ° C * 4,200 J * kg / ° C = 420 kJ.
Then we get that to melt the ice and then heat the resulting water, we need: 680,000 J + 420,000 J = 1,100,000 Joules, or 1.1 Megajoules.
Knowing the temperature at which ice melts, one can solve many difficult problems in physics or chemistry.
Finally
So, in this article we learned some facts about water and its two aggregate states - solid and liquid. Water vapor, however, is an equally interesting subject to study. For example, in our atmosphere contains approximately 25 * 10 16 cubic meters of water vapor. In addition, unlike freezing, the evaporation of water occurs at any temperature and accelerates when it is heated or in the presence of wind.
We learned at what temperature ice melts and freezes liquid water. Such facts will always be useful to us in everyday life, since water surrounds us everywhere. It is important to always remember that water, in particular fresh water, is the Earth's exhaustible resource and needs to be treated with care.