γλώσσες
Σελίδες
Νομικός
Chapter 13
Phase Changes
ΔH Quiz
• Calorimetry • Signs for ΔH for endo/exo reac?ons • Poten?al energy diagrams
• ΔH from poten?al energy diagrams
• Thermochemical stoichiometry
Two basic proper?es of the gas phase are
A.) a definite shape and a definite volume
B.) a definite shape but no definite volume
C.) no definite shape but a definite volume
D.) no definite shape and no definite volume
Two basic proper?es of the gas phase are
A.) a definite shape and a definite volume
B.) a definite shape but no definite volume
C.) no definite shape but a definite volume
D.) no definite shape and no definite volume
SOLID
LIQUID
Which substance has vibra?ng par?cles in regular, fixed posi?ons?
A.) Ca(s)
B.) Hg(l)
C.) Cl2(g)
D.) CaCl2(aq)
Which substance has vibra?ng par?cles in regular, fixed posi?ons?
A.) Ca(s)
B.) Hg(l)
C.) Cl2(g)
D.) CaCl2(aq)
The circle on the leP shows a magnified view of a very small
por?on of liquid water in a closed container.
A.) B.) C.) D.) E.)
What would the magnified view show aPer the water evaporates?
Boiling water is a physical change
A,B, and D -‐ Water molecules are not decomposed into hydrogen and oxygen gas (hydrogen is flammable and oxygen supports combus?on, if these gases were created there would be explosions every ?me you boiled water)
C – the par?cles do not vanish (Law of Conserva?on of MaWer)
E – when water molecules boil, they remain water, the par=cle simply move farther away from one another
Which grouping of the three phases of bromine is listed in order from leP to right for increasing distance between bromine
molecules?
A.) gas, liquid, solid
B.) liquid, solid, gas
C.) solid, gas, liquid
D.) solid, liquid, gas
Which grouping of the three phases of bromine is listed in order from leP to right for increasing distance between bromine
molecules?
A.) gas, liquid, solid
B.) liquid, solid, gas
C.) solid, gas, liquid
D.) solid, liquid, gas
Par?cle Movement in Phases
Solid Par?cles held together by strong forces of aWrac?on
Movement is restricted to vibra?ng in fixed posi?ons
Definite shape and volume
Par?cle Movement in Phases
Liquid Par?cles have aWrac?on for one another Par?cles flow around each other Definite volume, takes the shape of its container
Par?cle Movement in Phases
Gas Par?cles have no aWrac?on for each other Par?cles in constant, random mo?on
Indefinite shape and volume (expands to fill container)
ANIMATION
Endothermic Phase Changes
• Solid Liquid – Mel?ng; Fusion
• Liquid Gas – Boiling; Vaporiza?on
• Solid Gas – Sublima?on
Exothermic Phase Changes
Gas Liquid Condensa?on
Liquid Solid Freezing; Solidifica?on
Gas Solid Deposi?on
S L G
ENDOTHERMIC
NEEDS ENERGY
EXOTHERMIC
RELEASES ENERGY
Which phase change is an exothermic process?
A.) CO2(s) CO2(g)
B.) NH3(g) NH3(l)
C.) Cu(s) Cu(l)
D.) Hg(l) Hg(g)
Which phase change is an exothermic process?
A.) CO2(s) CO2(g)
B.) NH3(g) NH3(l)
C.) Cu(s) Cu(l)
D.) Hg(l) Hg(g)
Which change is exothermic?
A.) freezing of water
B.) mel?ng of iron
C.) vaporiza?on of ethanol
D.) sublima?on of iodine
Which change is exothermic?
A.) freezing of water
B.) mel?ng of iron
C.) vaporiza?on of ethanol
D.) sublima?on of iodine
A 1.0-‐gram sample of solid iodine is placed in a tube and the tube is sealed aPer all of the air is removed. The tube and the solid iodine together weigh 27.0 grams.
A.) less than 26.0 grams. B.) 26.0 grams. C.) 27.0 grams. D.) 28.0 grams. E.) more than 28.0 grams.
The tube is then heated un?l all of the iodine sublimes and the tube is filled with iodine gas.
Will the weight aPer hea?ng be:
A 1.0-‐gram sample of solid iodine is placed in a tube and the tube is sealed aPer all of the air is removed. The tube and the solid iodine together weigh 27.0 grams.
A.) less than 26.0 grams. B.) 26.0 grams. C.) 27.0 grams. D.) 28.0 grams. E.) more than 28.0 grams.
The tube is then heated un?l all of the iodine sublimes and the tube is filled with iodine gas.
Will the weight aPer hea?ng be:
Par?cle mass does not depend on phase
Assume a beaker of pure water has been boiling for 30 minutes. What is in
the bubbles in the boiling water? A.) Air
B.) Oxygen gas and hydrogen gas
C.) Oxygen
D.) Water vapor
E.) Heat
Assume a beaker of pure water has been boiling for 30 minutes. What is in
the bubbles in the boiling water? A.) Air
B.) Oxygen gas and hydrogen gas
C.) Oxygen
D.) Water vapor
E.) Heat
A glass of cold milk sometimes forms a coat of water on the outside of the glass (Often referred to as 'sweat'). How does
most of the water get there?
A.) Water evaporates from the milk and condenses on the outside of the glass.
B.) The glass acts like a semi-permeable membrane and allows the water to pass, but not the milk.
C.) Water vapor condenses from the air. D.) The coldness causes oxygen and hydrogen from
the air combine on the glass forming water.
A glass of cold milk sometimes forms a coat of water on the outside of the glass (Often referred to as 'sweat'). How does
most of the water get there?
A.) Water evaporates from the milk and condenses on the outside of the glass.
B.) The glass acts like a semi-permeable membrane and allows the water to pass, but not the milk.
C.) Water vapor condenses from the air. D.) The coldness causes oxygen and hydrogen from
the air combine on the glass forming water.
You take a swim in the swimming pool. Although it is a hot day when you come out,
you feel cold. Which of the following statements is TRUE?
A.) The water in the pool is warmer than the air
B.) The water in the pool is colder than the air
C.) The water on your skin gets cold when you step out of the pool
D.) The water on your skin evaporates
You take a swim in the swimming pool. Although it is a hot day when you come out,
you feel cold. Which of the following statements is TRUE?
A.) The water in the pool is warmer than the air
B.) The water in the pool is colder than the air
C.) The water on your skin gets cold when you step out of the pool
D.) The water on your skin evaporates
L G is endothermic, absorbing heat energy from your body
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