Hydrosphere

Specific Heat Capacity The amount of heat required to raise the temperature of 1g of a substance 1°C The amount of heat required to raise the temperature of 1g of a substance 1°C The higher the specific heat capacity the more energy required to heat it The higher the specific heat capacity the more energy required to heat it

Using the specific heat capacity of a substance you can determine: Using the specific heat capacity of a substance you can determine: 1.How much energy a substance requires to raise its temperature a certain amount 2.How much energy is released when a substance cools down

Q=mcΔT Q=amount of heat in joules (released or required) (J) m=mass (g) (must be in grams) c=specific heat capacity of substance (J/[(g)(°C)] ΔT=change in temperature (°C) Note: If when you solve for Q you get a negative answer it just means energy is released instead of absorbed

Phase Changes Water and other substances can absorb and release energy with no change in temperature Water and other substances can absorb and release energy with no change in temperature Energy is required to melt ice and cause liquid water to evaporate Energy is required to melt ice and cause liquid water to evaporate While energy is being used for this action to occur it does not result in the temperature increasing While energy is being used for this action to occur it does not result in the temperature increasing –The energy is instead used to break bonds Energy is released when bonds are formed (eg. Water forming into ice) Energy is released when bonds are formed (eg. Water forming into ice)

Phase Change: a physical change from one state to another Phase Change: a physical change from one state to another –Freezing, melting, evaporating, condensing Heat of Fusion (H fus ): the amount of energy required to melt one mole of a substance Heat of Fusion (H fus ): the amount of energy required to melt one mole of a substance Heat of Vaporization (H vap ): the amount of energy required to convert one mole of substance from a liquid to a gas Heat of Vaporization (H vap ): the amount of energy required to convert one mole of substance from a liquid to a gas Each substance has its own H fus and H vap Each substance has its own H fus and H vap

SubstanceHeat of Fusion H fus (J/mol) Heat of Vaporization H vap (kJ/mol) water ammonia methanol nitrogen oxygen

Energy Required for Melting Q=n H fus Energy Required for Evaporation Q=nH vap Q=amount of heat (J) n=number of moles of substance (mol) H fus = heat of fusion of substance (J/mol) H vap = heat of vaporization of substance (J/mol)

Remember: Remember: n=m M n=number of moles (mol) m=mass of substance (g) M=molar mass of compound (g/mol) [*use the periodic table to find molar mass]

Unique Properties of Water Influence Climate There are 3 unique properties of water that influence climate: There are 3 unique properties of water that influence climate: 1.Water has a high specific heat capacity (4.19 J/[(g)(°C)] 2.Water has a high heat of vaporization (40.68 kJ/mol) 3.Water has a high heat of fusion (6.01 kJ/mol)

1. Water has a high specific heat capacity: –Thus, large amounts of energy are needed to change the temperature –Large bodies of water have a moderating effect on the air temperature of nearby land communities since they absorb a large amount of heat during the day and the summer –The water releases heat slowly at night and during the winter

2. Water has a high heat of vaporization –For water to evaporate, a large amount of energy is needed to break the attractive forces among water molecules –This allows bodies of water to remain at relatively stable temperatures and allows aquatice species to survive

3. Water has a high heat of fusion –As water cools below 4°C it begins to expand and continues to do so until it freezes –Thus, ice floats on the surface of water because its density is lower than that of liquid water –Ice acts as an insulating layer and prevents excessive loss of heat from the water permitting most aquatic organisms to survive until spring