Slide 1

Review: LIQUIDS & PHASE CHANGES

Phase Change: solid to liquid MeltingwaterMost solids shrink in size when frozen. What substance is an exception and actually expands?

GASUse the phase diagram below to answer the following question. What phase of matter would this substance be in at 90C and 0.25atm?

ABCHeat energy is either absorbed or releasedWhat can cause a phase change of matter?What phase of matter is B?

ABCTemperature Pressure

Liquid________is the gas phase of a substance normally solid or liquid at room temperatureVapor C(s) + H2O(g) CO(g) + H2(g) If the concentration of C was decreased, the system would shift to the ________

LEFTFreezing occurs by the release of _____energyDescribe a volatile liquid in terms of its rate of evaporation.Evaporates quickly______ is the resistance of a liquid to flowViscosityWhat phase of matter is A?

ABCTemperature Pressure

SolidA _____________ is a graph of pressure versus temperature that shows which phase a substance exists in under different conditions of temperature and pressure.Phase diagramWhat is the normal boiling point of water?

100C

Melting occurs by energy being ______.absorbedReleasedDeposition occurs when energy is (absorbed OR released).

____________ is the temperature and pressure at which all 3 states of matter are at equilibriumTriple pointPhase Change: solid to gas SublimationThe triple point of this substance occurs at:5.2 atm & 216.6 K

When a system at equilibrium is disturbed by application of a stress, it attains a new equilibrium position that minimizes the stress. This is known as ___________Le Chateliers Principle C(s) + H2O(g) CO(g) + H2(g) If the concentration of CO was increased, the system would shift to the ________

LEFT_______ is the pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temperature.Equilibrium vapor pressure________ is the temperature at which equilibrium vapor pressure equals atmospheric pressure

Boiling point__________ is a dynamic condition in which two opposing physical or chemical changes occur at equal rates in a given closed system Equilibrium____________ is the spontaneous mixing of two or more substances.DiffusionWhen does a liquid boil?Equilibrium vapor pressure EQUALS atmospheric pressureWhat is the most abundant liquid?Water_____________ is the energy required to increase the surface area of a liquid by a given amount; results from an uneven distribution of attractive forces.Surface tensionList 2 examples of surface tension.MeniscusDroplets can formObjects floatCapillary rise

List a volatile substanceRubbing alcoholNail polish removerGasolinehairsprayWhen energy is taken away from a substance, the particles would move __________SlowerPhase Change: liquid to solid FreezingWhat happens to the boiling point of liquids on top of Mt. Everest? WHY?Boiling point is lowerB/c atmospheric pressure is lower C(s) + H2O(g) CO(g) + H2(g) If the concentration of H2O was increased, the system would shift to the ________

RightHow does a substance evaporate, if equilibrium vapor pressure is LOW? WHY?SLOWLY!B/c there are STRONG IM forces and requires MORE kinetic energy to become a vaporDescribe a liquid in terms of particle spacing.Particles are packed relatively closely togetherDescribe a liquid in terms of particle motion.Particles vibrate around MOVING pointsWater, olive Oil, Tree SapArrange the following in order of increasing viscosity at room temperature: tree sap, water, olive oil. C(s) + H2O(g) CO(g) + H2(g) If the concentration of H2 was decreased, the system would shift to the ________

RIGHTPhase Change: gas to liquid CondensationDescribe the general volume of a liquid and use KMT to explain.Definite VOLUME- b/c particles are close togetherDescribe the general shape of a liquid and use KMT to explain.NO Definite SHAPE- b/c particles vibrate around moving pointsDescribe a liquid-vapor system at equilibrium.The number of particles vaporizing is EQUAL to the number of particles condensingUnequal distribution of charge (oxygen is partially negative while hydrogen is partially positive)Why water is considered a polar molecule?

Phase Change: gas to solidDepositionBoth have particles changing from a liquid to a gas (vaporization)How are boiling and evaporation alike? Phase Change: liquid to gas VaporizationTemp. remains constant (does not change!)What happens to the temperature of substance during a phase change?Phase change__________ is the transitioning from one state of matter to another.

SolidUse the phase diagram below to answer the following question. What phase of matter would this substance be in at 10C and 1.0atm?

ABCEvaporation ONLY takes place at the surface and boiling vaporization is throughout liquid

Heat is needed for boiling to occur and not for evaporationHow are boiling and evaporation different? List one differenceRELEASEDCondensation occurs when energy is (absorbed OR released).

What phase of matter is C?

ABCTemperature Pressure

GasWhat is the difference between the IM forces during melting and freezing?Melting = Less IM forces b/c more particle collisionsFreezing = MORE IM forces b/c particles are moving slowerUsing KMT, explain the evaporation rate of a volatile liquid.Quick evaporation rate.Has weak IM forces between particles so it requires LESS kinetic energy to become a vaporUsing KMT, explain the evaporation rate of a nonvolatile liquid.Slow evaporation rateHas strong IM forces between particles so it requires MORE kinetic energy to become a vaporRubbing Alcohol it evaporates quickly b/c there is WEAK IM forces between the particlesWhich would you expect to be more volatile, water or rubbing alcohol? Explain. B/c of the hydrogen bonding- the arrangement of the molecules in the solid crystalline structure take up more space, yet have the same mass; making ice less dense than liquid water.

Explain why the solid state of water (ice) is less dense than the liquid state.When energy is added to a substance, the particles would move ___________FasterEnergy exchanges are not changes in kinetic energy so temperature remains constant. Heat energy is used to change the IM forces between the molecules

Explain why the temperature remains constant during a phase change.FALSE they are the same = 0CTRUE or FALSE: The temperature at which a substance freezes is lower than the temperature at which it melts.Why?