Water as a unique chemical Flashcards
What are the properties of water?
- Relatively high MP and BP
- Expands when freezing
- High specific heat capacity
- High latent heat value
Why does water have a high MP and BP
Because of its structure and intermolecular forces. Necause water is bound together by hydrogen bonding, a large amount of heat and energy is required to weaken and break the bonds.
Why does water expand when freezing?
Ice has an open ring structure, meaning the hydrogen bonds cause water to arrange in a crystalline manner. This means that it moves from being closely packed when in liquid form to an open ring structure when frozen, ultimately taking up more space.
What does specific heat capacity mean?
The amount of heat energy required to raise the temperature of 1g of a substance by 1 degree C
What is water’s specific heat capacity?
4.18 J c/g
What is the equation to calculate specific heat capacity, and what do each of the symbols mean?
q=mcΔT
Where:
q=energy released/absorbed in J
m= mass (g)
ΔT= change in temperature
What is latent heat value?
The amount of energy required to change the state of a substance without changing its temperature.
Why does water have a high latent heat value?
Due to hydrogen bonds, water can absorb lots of heat before changing state
What is the latent heat equation?
q = nL
Where:
q = heat energy kJ
n = amount (mol)
L = latent heat value of fusion or vaporisation (kJ/mol)
How does water impact the ocean temperature?
The high specific heat capacity of water acts as a buffer, allowing the ocean temperature to stay within relatively narrow limits despite fluctuations in the outside temperature. This protects the marine life within the ocean.
Water is constantly evaporating at the surface of the ocean, meaning the high latent heat of vaporisation allows for water to absorb a large amount of heat, where the lower layers of water stay cool.
