Environmental chem. topic 3 Flashcards
What’s the specific heat capacity of water?
4.19
What’s the Q in Q=MCAT
the quantity of thermal energy in
joules (J)
What’s the M in Q=MCAT
the mass of the substance in grams
(g)
Whats the C in Q=MCAT
the specific heat capacity of the
substance in J/g*˚C
What’s the AT in Q=MCAT
change in temperature in ˚C
Heat of fusion phase change?
solid to liquid
Heat of fusion is energy absorbed or realized?
Absorbed
Heat of fusion the amount of water (Kj/mol)?
6.01
heat of solidification is energy absorbed or released?
Released
Heat of solidification the amount of water (Kj/mol)?
6.01
Heat of vaporization is energy realsed or absorbed?
absorbed
Heat of vaporization is energy the amount of water?
40.66
In Q=HxN what’s Q?
= quantity of thermal energy added in kJ
In Q=HxN what’s N?
the amount of the substance in mol
How much thermal energy is required to increase the temperature of 500 g
of water from 20.0C to 80.0C? The specific heat capacity of water is 4.19 J/g·ºC.
125,700J
When 200 g of an unknown substance absorbs 4.30 kJ of thermal energy, the
temperature of the substance changes from 30.0C to 80.0C. Determine the
experimental specific heat capacity of the unknown substance.
0.43j/g˚c
How much thermal energy is needed to heat 100 g of water at 25.0ºC to 100.0ºC,
without a change in phase? The theoretical specific heat capacity of water is 4.19
J/g·ºC.
31425
b) How much thermal energy is absorbed when 100 g of water at 100.0ºC evaporates
completely, without a change in temperature? The heat of vaporization of water is 40.7
kJ/mol and the molar mass of water is 18.02 g/mol.
225.5 kj
c) Using your answers from part a) and b) of question 28, calculate the amount of thermal energy needed to heat 100 g of liquid water at 25.0ºC to water vapour at 100.0ºC. Assume that all the water evaporates.
1279.12 kj/mol
