Biological Molecules. ch2 Flashcards
why is water important
it is a universal solvent
it has high specific heat capacity
it has high latent heat of vaporization.
explain the point: Water is a universal solvent
water makes up about 50% of our blood. It dissolves substances such as glucose, amino acids and salts. It also acts as a transport medium
explain the point: water has a high specific heat capacity
If water and ethanol(both of same volume and temperature) are to be heated from 36”C to 37”C. The amount of heat required to heat the water would be more that the heat required for the ethanol.
why is this so?
This is because of the hydrogen bonds between water molecules. Extra heat will be required to break apart these bonds, before more heat will be applied to increase the molecules kinetic energy for the temperature to increase.
explain why high specific heat capacity is important for life
Imagine if you were a room of room temperature (37”C) and you step out int the scorching sun. Your temperature wouldn’t instantaneously go up. This is because our body is of about 50% water, and the water in our body is resisting the heat. The temperature of water in our body does not easily go up because of waters high specific heat capacity
explain the point: high latent heat of vaporization
Latent heat of vaporization is the amount of heat energy required to change liquid water to water vapour.
explain why latent heat of vaporization is important for life
A human body is at a temperature of 38”C and it wants to be cooled down. One body has water on top of it, and the other has ethanol. They are both of the same volume. The water is going to absorb more heat energy than the ethanol. why is that? This is because extra heat from the body will be absorbed to break the hydrogen bonds between water molecules, before more heat will be taken to increase the waters kinetic energy for it to turn to vapor. So the temperature decreases to 37”C. Unlike water, ethanol has a low specific heat capacity, hence little heat is absorbed and evaporated. So there is still a lot of heat left in the body (37”C)
why does water have a high latent heat of vaporization?
This is due to waters hydrogen bonds. the extra heat will be required to break hydrogen bonds, before more heat is taken to turn the water molecules into vapour
