Measuring the Quantity of Heat
The specific heat capacity refers to the amount of heat required to cause a unit of The relationship between these four quantities is often expressed by the. Specific heat capacity and heat of vaporization of water. Evaporative cooling. Why ice floats. What's the equation for the rate of thermal conduction? There are four factors .. heat and heat transfer. Specific heat and latent heat of fusion and vaporization.
Hydrogen bonding explains both the effectiveness of evaporative cooling why sweating cools you off and the low density of ice why ice floats. Solid, liquid, and gas Water has unique chemical characteristics in all three states—solid, liquid, and gas—thanks to the ability of its molecules to hydrogen bond with one another.
Since living things, from human beings to bacteria, have a high water content, understanding the unique chemical features of water in its three states is key to biology. In liquid water, hydrogen bonds are constantly being formed and broken as the water molecules slide past each other. The breaking of these bonds is caused by the energy of motion kinetic energy of the water molecules due to the heat contained in the system. When the heat is raised for instance, as water is boiledthe higher kinetic energy of the water molecules causes the hydrogen bonds to break completely and allows water molecules to escape into the air as gas.
We observe this gas as water vapor or steam. On the other hand, when the temperature drops and water freezes, water molecules form a crystal structure maintained by hydrogen bonding as there is too little heat energy left to break the hydrogen bonds. This structure makes ice less dense than liquid water. Specifically, in ice, the water molecules are pushed farther apart than they are in liquid water. That means water expands when it freezes.
- Specific heat, heat of vaporization, and density of water
- Specific heat capacity
- Change of state and latent heat
You may have seen this for yourself if you've ever put a sealed glass container containing a mostly-watery food soup, soda, etc. With most other liquids, solidification—which occurs when the temperature drops and kinetic motion energy of molecules is reduced—allows molecules to pack more tightly than in liquid form, giving the solid a greater density than the liquid.
Water is an anomaly that is, a weird standout in its lower density as a solid. Left Crystal structure of ice, with water molecules held in a regular 3D structure by hydrogen bonds. Right Image of icebergs floating on the surface of the ocean.
Because it is less dense, ice floats on the surface of liquid water, as we see for an iceberg or the ice cubes in a glass of iced tea. In lakes and ponds, a layer of ice forms on top of the liquid water, creating an insulating barrier that protects the animals and plant life in the pond below from freezing. Why is it harmful for living things to freeze? We can understand this by thinking back to the case of a bottle of soda pop cracking in the freezer.
When a cell freezes, its watery contents expand and its membrane just like the soda bottle is broken into pieces. Heat capacity of water It takes a lot of heat to increase the temperature of liquid water because some of the heat must be used to break hydrogen bonds between the molecules.
In other words, water has a high specific heat capacity, which is defined as the amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius. Learn how to identify the specific heat capacity of other common materials and how to calculate specific heat capacity with an experiment. How to Calculate Specific Heat Have you ever wondered why it takes so long to boil water?Heat Capacity, Specific Heat, and Calorimetry
Do you know that it takes longer to boil some liquids than it does others? For example, if you were to heat the same amount of water and alcohol, the alcohol boils first.
Well, what accounts for this difference? The answer is specific heat capacity. Specific heat capacity, or simply specific heat, is the amount of heat required to change the temperature of a substance.
As water requires more time to boil than does alcohol, you might conclude that water requires more heat than alcohol to raise its temperature.
In other words, water has a higher specific heat capacity. That conclusion would be accurate.
How to Calculate Specific Heat Capacity for Different Substances
To better understand specific heat capacity, we need to distinguish between heat and temperature, as both of these terms are used in its definition.
The Difference Between Heat and Temperature Let's look at an example to help us understand the difference between heat and temperature. Consider two beakers of boiling water with 1 liter in one and 2 liters in the other.
If both are boiling, they have the same temperature.
Specific heat, heat of vaporization, and density of water (article) | Khan Academy
You see, temperature is defined as the average amount of kinetic energy in the substance, where kinetic energy is the energy of motion.
The molecules in each pot have the same average energy of motion or average amount of kinetic energy. In other words, the water molecules in each pot are moving at the same speed.