ENERGIZING PROBLEMS Flashcards
(30 cards)
Why do wax phase changes require more energy
wax has bigger molecules
Why are combustion energy values higher than the energy given off or taken in during a phase change?
Combustion energy values are higher than phase changes because they are chemical changes
What is a seed crystal
catalyst, a substance/ surface for molecules to cling to when having a phase change
Which is a better way to obtain ocean water: Freezing or boiling it?
Freezing, it requires significantly less amount of energy than boiling
HoV> HoF
Which would cause a more severe burn: 100 degree steam or 100 degree water? Why?
Steam
Steam has the energy from the transfer of energy from liquid <-> gas
Temperature change
MCΔT
Endothermic
adding energy (cold-> hot)
Kinetic energy
energy in motion (observable)
Exothermic
taking energy ( hot -> cold)
potential energy
stored energy
Is the melting point of the substance the same as the freezing point
yes
Kinetic Molecular Theory
KMT
Molecules are always coming
if you add heat or a chemical reaction (catalyst) they move faster
How do you describe the warming and cooling behavior of a solid pure substance
with a graph showing the temperatures and phase changes
What category of energy is a temperature change
Kinetic energy
What category of energy is a phase change
Potential
ΔT
MCΔT
ΔP
HoV or HoF
Colder water is ________ than warm water
denser
Joule
4.184 3/GxC
Calorie
energy required to raise 1.0 g of H2O 1 degree
1000 cals= ? Kcal
1 Kcal
Heat of Fusion
solid to fluid
Does the whole substance have to melt to accurately calculate ?
yes, in order for accurate calculations you must have a complete phase change
What is the best way to calculate the heat of fusion of a substance
completely melt the substance
then put into room temperature water
track temp change
when substance freezes mark temp of water and find difference from initial
