Unit 3 - Physical Unit 3 - Physical Properties & Properties & Intermolecular Intermolecular Interactions Interactions When discussing the physical properties of When discussing the physical properties of molecules the discussion often focuses on molecules the discussion often focuses on topics such as melting points, boiling points topics such as melting points, boiling points and solubilities in various solvents. These are and solubilities in various solvents. These are considered physical properties because they do considered physical properties because they do not change the composition or identity of the not change the composition or identity of the molecules involved. At the heart of these molecules involved. At the heart of these discussions is what causes molecules to be discussions is what causes molecules to be attracted to and repelled by one another. This attracted to and repelled by one another. This discussion is critical to our understanding discussion is critical to our understanding biological systems. biological systems.
When discussing the physical properties of When discussing the physical properties of molecules the discussion often focuses on topics molecules the discussion often focuses on topics
such as melting points, boiling points and such as melting points, boiling points and solubilities in various solvents. These are solubilities in various solvents. These are
considered physical properties because they do not considered physical properties because they do not change the composition or identity of the molecules change the composition or identity of the molecules involved. At the heart of these discussions is what involved. At the heart of these discussions is what
causes molecules to be attracted to and repelled by causes molecules to be attracted to and repelled by one another. This discussion is critical to our one another. This discussion is critical to our
For molecular substances there are basically three states or For molecular substances there are basically three states or phases of matter.phases of matter.
• Solids (Solids (ss): Molecules are held in place by intermolecular ): Molecules are held in place by intermolecular interactions.interactions.
• Liquids (Liquids (ll): Molecules are held next to one another by ): Molecules are held next to one another by noncovalent, intermolecular interactions, however, these noncovalent, intermolecular interactions, however, these interactions are not strong enough to prevent the interactions are not strong enough to prevent the molecules from flowing past one another.molecules from flowing past one another.
• Gases (s): The intermolecular interactions are too weak to Gases (s): The intermolecular interactions are too weak to hold the molecules next to one another, so the molecules hold the molecules next to one another, so the molecules wander off on their own.wander off on their own.
Water vapor, HWater vapor, H22O(O(gg))Water vapor, HWater vapor, H22O(O(gg))
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States of MatterStates of Matter
The strength and numbers of the noncovalent intermolecular The strength and numbers of the noncovalent intermolecular interactions determine which state a molecular substance is interactions determine which state a molecular substance is in.in.• The predominant noncovalent interaction between water The predominant noncovalent interaction between water
molecules is the hydrogen bond:molecules is the hydrogen bond:
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Questions (Clickers)Questions (Clickers)
If you were interested in disrupting the noncovalent If you were interested in disrupting the noncovalent interactions between water molecules in ice you could:interactions between water molecules in ice you could:
A)A) Shine light on the ice.Shine light on the ice.
B)B) Stick the ice in a freezer.Stick the ice in a freezer.
C)C) Hit the ice with a hammer.Hit the ice with a hammer.
D)D) Add heat to the ice.Add heat to the ice.
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States of MatterStates of Matter
These interactions can be disrupted by adding heat.These interactions can be disrupted by adding heat.• Adding heat increases the kinetic energy of the moleculesAdding heat increases the kinetic energy of the molecules
This is most readily observed with gases by looking at the This is most readily observed with gases by looking at the Ideal Gas Law equation:Ideal Gas Law equation:• As the temperature of a gas increases, so does its kinetic As the temperature of a gas increases, so does its kinetic
A as heat is added to a molecular substance, it warms until A as heat is added to a molecular substance, it warms until reaching one of the phase transition temperature.reaching one of the phase transition temperature.• At that point the heat (kinetic energy) that is added to the At that point the heat (kinetic energy) that is added to the
substance is used to break the noncovalent, intermolecular substance is used to break the noncovalent, intermolecular interactions.interactions.
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States of MatterStates of Matter
For a more detailed description of phase transitions, along For a more detailed description of phase transitions, along with an animation of the process,with an animation of the process,see the Chem 150see the Chem 150Elaboration - States of Matter
When heat is added to liquid propane, (CHWhen heat is added to liquid propane, (CH33CHCH22CHCH33), it ), it warms until reaching the boiling point, and then changes into warms until reaching the boiling point, and then changes into a gas. Which of the following statements most accurately a gas. Which of the following statements most accurately describes what is going on:describes what is going on:
A)A) The added kinetic energy is causing the carbon and The added kinetic energy is causing the carbon and hydrogen atoms in propane to separate from one another.hydrogen atoms in propane to separate from one another.
B)B) The added kinetic energy is causing the disruption of both The added kinetic energy is causing the disruption of both hydrogen bonds and London dispersion forces between the hydrogen bonds and London dispersion forces between the propane molecules.propane molecules.
C)C) The added kinetic energy is causing the disruption of the The added kinetic energy is causing the disruption of the London dispersion forces between the propane molecules.London dispersion forces between the propane molecules.
D)D) The added kinetic energy is causing the propane to change The added kinetic energy is causing the propane to change into methane gas.into methane gas.
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Questions (Clickers)Questions (Clickers)
When heat is added to liquid ethanol, (CHWhen heat is added to liquid ethanol, (CH33CHCH22OH), it warms OH), it warms until reaching the boiling point, and then changes into a gas. until reaching the boiling point, and then changes into a gas. Which of the following statements accurately describes what Which of the following statements accurately describes what is going on:is going on:
A)A) The added kinetic energy is causing the carbon and The added kinetic energy is causing the carbon and hydrogen atoms to separate from one another.hydrogen atoms to separate from one another.
B)B) The added kinetic energy is causing the disruption of both The added kinetic energy is causing the disruption of both hydrogen bonds and London dispersion forces between the hydrogen bonds and London dispersion forces between the ethanolethanol molecules. molecules.
C)C) The added kinetic energy is causing the disruptions of the The added kinetic energy is causing the disruptions of the London dispersion forces between the London dispersion forces between the ethanolethanol molecules. molecules.
D)D) The added kinetic energy is causing the ethanol to change The added kinetic energy is causing the ethanol to change into methane gas and water vapor.into methane gas and water vapor.
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Questions (Clickers)Questions (Clickers)
Both propane (Both propane (MM = 44 = 44 g/molg/mol) and ethanol () and ethanol (MM = 46 = 46 g/molg/mol) ) have comparable molecular weights. Which do you predict have comparable molecular weights. Which do you predict has the higher boiling point? Explain why.has the higher boiling point? Explain why.
A)A) They should have similar boiling points.They should have similar boiling points.
B)B) The ethanol should have the higher boiling point.The ethanol should have the higher boiling point.
C)C) The propane should have the higher boiling point.The propane should have the higher boiling point.
D)D) It is hard to tell without doing the experiment.It is hard to tell without doing the experiment.
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Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
Energy is defined as Energy is defined as the ability to do workthe ability to do work..
• The heat energy we have been talking about is also called The heat energy we have been talking about is also called Enthalpy (Enthalpy (HH))
• It was used to do the work of breaking the noncovalent, It was used to do the work of breaking the noncovalent, intermolecular interactions present in solids and liquids.intermolecular interactions present in solids and liquids.
• When Enthalpy is put into an object, such as an ice cube, When Enthalpy is put into an object, such as an ice cube, the change in Enthalpy for the ice cube increases.the change in Enthalpy for the ice cube increases.
• ((ΔH > ΔH > 0). the 0). the ΔΔ symbol means “change in”. symbol means “change in”.
• Changes in nature can be either Changes in nature can be either spontaneousspontaneous (favorable), (favorable), or or nonspontaneousnonspontaneous (unfavorable). (unfavorable).
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Questions (Clickers)Questions (Clickers)
When the ice melts from the surface of a pond on a warm When the ice melts from the surface of a pond on a warm spring day, this change isspring day, this change is
A)A) spontaneousspontaneous
B)B) nonspontaneousnonspontaneous
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Questions (Clickers)Questions (Clickers)
When the ice forms on the surface of a pond on a cold winter When the ice forms on the surface of a pond on a cold winter day, this change isday, this change is
A)A) spontaneousspontaneous
B)B) nonspontaneousnonspontaneous
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Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
• Why are some changes spontaneous while others are Why are some changes spontaneous while others are nonspontaneous?nonspontaneous?
• Why, like the ice on a pond, are changes spontaneous Why, like the ice on a pond, are changes spontaneous some of the time and nonspontaneous at other times?some of the time and nonspontaneous at other times?
• Asking some questions about the energy changes that take Asking some questions about the energy changes that take place can to help answer theses questionsplace can to help answer theses questions
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Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
Changes occur spontaneously in nature when energy is Changes occur spontaneously in nature when energy is released.released.
• The case of the rolling stone.The case of the rolling stone.
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Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
Although Enthalpy is a form of energy, it alone cannot be Although Enthalpy is a form of energy, it alone cannot be used to answer these questions.used to answer these questions.
• The melting of the ice from a pond on a warm spring day is The melting of the ice from a pond on a warm spring day is spontaneousspontaneous
• However, the ice is absorbing heat (However, the ice is absorbing heat (ΔΗΔΗ > 0) (endothermic) > 0) (endothermic)
A second factor called Entropy (A second factor called Entropy (SS), needs to also be ), needs to also be considered to determine if a change is spontaneous or considered to determine if a change is spontaneous or nonspontaneous.nonspontaneous.
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Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
Entropy is a measure of disorder.Entropy is a measure of disorder.
• When When ΔS ΔS > 0, things become more disorder.> 0, things become more disorder.
• Nature prefers things to be disordered:Nature prefers things to be disordered:
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Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
Enthalpy and Entropy can be combined to calculate another Enthalpy and Entropy can be combined to calculate another type of energy called type of energy called Free EnergyFree Energy ( (GG).).
• ΔG = ΔΗ - ΤΔSΔG = ΔΗ - ΤΔS
The change in Free Energy can be used to predict whether a The change in Free Energy can be used to predict whether a change is spontaneous or nonspontaneous.change is spontaneous or nonspontaneous.
• When When ΔGΔG < 0, the change is spontaneous (favorable) < 0, the change is spontaneous (favorable)
• When When ΔGΔG > 0, the change is nonspontaneous > 0, the change is nonspontaneous (unfavorable)(unfavorable)
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Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
When Ice melts, When Ice melts, ΔHΔH > 0 and > 0 and ΔSΔS > 0 > 0
• It gains heat and becomes more disorderedIt gains heat and becomes more disordered
Above the freezing temperature, Above the freezing temperature, TΔSTΔS > > ΔHΔH and and ΔGΔG is is negative ( negative ( ΔGΔG < 0) < 0)
Below the freezing Temperature, Below the freezing Temperature, TΔSTΔS < < ΔHΔH and and ΔGΔG is is positive ( positive ( ΔGΔG > 0) > 0)
• Ice does not melt spontaneously.Ice does not melt spontaneously.
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Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
When Ice freezes, When Ice freezes, ΔHΔH < 0 and < 0 and ΔSΔS < 0 < 0
• It loses heat and becomes more orderedIt loses heat and becomes more ordered• ΔHΔH makes a negative contribution to makes a negative contribution to ΔGΔG
• ΔSΔS makes a positive contribution to makes a positive contribution to ΔGΔG
Below the freezing Temperature, the magnitude of Below the freezing Temperature, the magnitude of TΔSTΔS < < ΔHΔH and and ΔGΔG is NEGATIVE ( is NEGATIVE (ΔGΔG < 0) < 0)
Above the freezing temperature, the magnitude of Above the freezing temperature, the magnitude of TΔSTΔS > > ΔHΔH and and ΔGΔG is positive ( is positive (ΔGΔG > 0) > 0)
Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
For a more detailed description using the enthalpy, entropy For a more detailed description using the enthalpy, entropy an free energy changes to predict if a process is spontaneous an free energy changes to predict if a process is spontaneous or not,or not,see the Chem 150see the Chem 150Elaboration - Ethalpy, Entropy & Free Energy
Enthalpy, Entropy and Free EnergyEnthalpy, Entropy and Free Energy
Figure 5.6, RaymondFigure 5.6, Raymond
ΔΔS < S < 00(molecules are more ordered)(molecules are more ordered)
ΔΔS < S < 00(molecules are more ordered)(molecules are more ordered)
ΔΔS > S > 00(molecules are more disordered)(molecules are more disordered)
ΔΔS > S > 00(molecules are more disordered)(molecules are more disordered)
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Questions (Clickers)Questions (Clickers)
Before going on a picnic on a hot sumer day, you stopby the Before going on a picnic on a hot sumer day, you stopby the store and pick up a block of dry ice, COstore and pick up a block of dry ice, CO22((ss).).
In terms of ΔIn terms of ΔHH alone, is the sublimation of dry ice alone, is the sublimation of dry ice
A)A) SpontaneousSpontaneous
B)B) NonspontaneousNonspontaneous
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Questions (Clickers)Questions (Clickers)
Before going on a picnic on a hot sumer day, you stopby the Before going on a picnic on a hot sumer day, you stopby the store and pick up a block of dry ice, COstore and pick up a block of dry ice, CO22((ss).).
In terms of ΔIn terms of ΔSS alone, is the sublimation of dry ice alone, is the sublimation of dry ice
A)A) SpontaneousSpontaneous
B)B) NonspontaneousNonspontaneous
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Questions (Clickers)Questions (Clickers)
Before going on a picnic on a hot sumer day, you stopby the Before going on a picnic on a hot sumer day, you stopby the store and pick up a block of dry ice, COstore and pick up a block of dry ice, CO22((ss).).
At 50°C (This is one hot day!!) the ΔAt 50°C (This is one hot day!!) the ΔGG for the sublimation of for the sublimation of dry ice as adry ice as a
A)A) negative value.negative value.
B)B) positive value.positive value.
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LiquidsLiquids
Liquids have various physical properties that reflect the Liquids have various physical properties that reflect the strength of the intermolecular interactions that hold the liquid strength of the intermolecular interactions that hold the liquid togethertogether• Boiling point temperatureBoiling point temperature• ViscosityViscosity
• Resistance to flowResistance to flow
• Vapor pressureVapor pressure
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LiquidsLiquids
ViscosityViscosity• Resistance to flowResistance to flow
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LiquidsLiquids
Vapor Pressure and Boiling Points are relatedVapor Pressure and Boiling Points are related• The boiling point is the temperature at which the vapor The boiling point is the temperature at which the vapor
pressure is equal to the atmospheric pressure.pressure is equal to the atmospheric pressure.
Vapor Pressure and Boiling Points are relatedVapor Pressure and Boiling Points are related• The boiling point is the temperature at which the vapor The boiling point is the temperature at which the vapor
pressure is equal to the atmospheric pressure.pressure is equal to the atmospheric pressure.
You planning to do some surgery on your kitchen table and You planning to do some surgery on your kitchen table and know that you need to sterilize your instruments by heating know that you need to sterilize your instruments by heating them to 120°C. You rummage around in the kitchen them to 120°C. You rummage around in the kitchen cupboards and find a pressure cooker that can heat water to cupboards and find a pressure cooker that can heat water to a pressure of 1.4 atm. Will this be sufficient for sterilizing your a pressure of 1.4 atm. Will this be sufficient for sterilizing your instruments? (You may use Table 5.6 in your book to answer instruments? (You may use Table 5.6 in your book to answer this question; see the previous slide.)this question; see the previous slide.)
•1.4 atm (760Torr/atm) = 1064 Torr•This is less than the pressure required to reach 110°C (1075 Torr), therefore it is an insufficient pressure to reach 120°C.•(120-100)/(125-100)*(1741-760)+760=~1544 Torr (interpolation)
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SolutionsSolutions
Biological systems are mixtures of substancesBiological systems are mixtures of substances• Pure substances contain only one type of element or Pure substances contain only one type of element or
compoundcompound• They contain only one type of atom or molecule:They contain only one type of atom or molecule:
‣ HH22
‣ HgHg
‣ OO22
‣ HH22OO
‣ sucrose (Csucrose (C1212HH2222OO1111))
• Mixtures contain more than one type of pure substanceMixtures contain more than one type of pure substance• Heterogeneous mixtureHeterogeneous mixture - - components are not evenly mixed at the molecular components are not evenly mixed at the molecular
level.level.
• Homogeneous mixtureHomogeneous mixture - - components are evenly mixed at the molecular level. components are evenly mixed at the molecular level.
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SolutionsSolutions
A A solutionsolution is another name for homogeneous mixture. is another name for homogeneous mixture.
• SolventSolvent - the major component in a solution - the major component in a solution
• SoluteSolute - the minor component in a solution. - the minor component in a solution.
A A solutionsolution is another name for homogeneous mixture. is another name for homogeneous mixture.
• Liquid solutions should be Liquid solutions should be clearclear (transparent). (transparent).
• Liquid solution’s solutes should not settle with timeLiquid solution’s solutes should not settle with time
This distinguishes solutions from This distinguishes solutions from suspensionssuspensions and and colloidscolloids..
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SolutionsSolutions
In order form a solution to formIn order form a solution to form• the solute molecules have to be able to form similar the solute molecules have to be able to form similar
noncovalent interactions with the solute molecules asnoncovalent interactions with the solute molecules as• the solute molecules form with themselvesthe solute molecules form with themselves• the solvent molecules form with themselves.the solvent molecules form with themselves.
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States of MatterStates of Matter
Simulation of Glycerol and PropaneDissolving in Waterr
SolubilitySolubility is a measure of how is a measure of how much solute will dissolve in a much solute will dissolve in a solvent.solvent.
Solubility depends on Solubility depends on temperature.temperature.
• The solubility of gases The solubility of gases decrease with increasing decrease with increasing temperaturetemperature
• The solubility of solids and The solubility of solids and liquids usually increase with liquids usually increase with increasing temperature.increasing temperature.
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SolutionsSolutions
When a solution is When a solution is saturatedsaturated, the solute dissolves and , the solute dissolves and precipitates at the same rate.precipitates at the same rate.
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SolutionsSolutions
In order form a solution to formIn order form a solution to form• the solute molecules have to be able to form similar the solute molecules have to be able to form similar
noncovalents with the solute molecules asnoncovalents with the solute molecules as• the solute molecules form with themselvesthe solute molecules form with themselves• the solute molecules form with themselves.the solute molecules form with themselves.
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Solubility of Gases in WaterSolubility of Gases in Water
Henry’s LawHenry’s Law - - The solubility of a gas in a liquid is The solubility of a gas in a liquid is proportional to the pressure of the gas over the liquid.proportional to the pressure of the gas over the liquid.
• The fizzing of soda when the cap is removed is an example The fizzing of soda when the cap is removed is an example of the lowered solubility of COof the lowered solubility of CO22 in water when it’s pressure in water when it’s pressure above the soda is descrease.above the soda is descrease.
• The solubility of COThe solubility of CO22 in water is very high, because it can in water is very high, because it can react with water to produce and even more soluble react with water to produce and even more soluble product, Hproduct, H22COCO3 3 (carbonic acid):(carbonic acid):
• We will see that this is a very important reaction in biochemistryWe will see that this is a very important reaction in biochemistry
CO2 + H2O H2CO3
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Nonpolar, organic solutes Nonpolar, organic solutes will dissolve readily in will dissolve readily in nonpolar, organic solvents.nonpolar, organic solvents.• ““Like dissolves Like”Like dissolves Like”
Organic CompoundsOrganic Compounds
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Organic CompoundsOrganic Compounds
The solubility is determined by the balance between the polar The solubility is determined by the balance between the polar and nonpolar portions of the molecule.and nonpolar portions of the molecule.
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Questions (Clicker)Questions (Clicker)
Pentanoic acid and 1-pentanol have the same number of Pentanoic acid and 1-pentanol have the same number of carbon atoms. Which one is expected to have the higher carbon atoms. Which one is expected to have the higher solubility in water? Explain.solubility in water? Explain.
A)A) Pentanoic acidPentanoic acid
B)B) 1 Pentanol1 Pentanol
C)C) NeitherNeither
CH3 CH2 CH2 CH2 C
O
OH CH3 CH2 CH2 CH2 CH2 OH
pentanoic acid 1-pentanol
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Biochemical Compounds &Biochemical Compounds &Their Interactions with WaterTheir Interactions with Water
Biological molecules are grouped into three categories.Biological molecules are grouped into three categories.
• Nonpolar molecules that cannot interact favorably with waterNonpolar molecules that cannot interact favorably with water
• Amphipathic molecules, which are conflicted about their Amphipathic molecules, which are conflicted about their feelings towards water.feelings towards water.
• Molecules containing both very polar and very nonpolar parts.Molecules containing both very polar and very nonpolar parts.
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Biochemical Compounds &Biochemical Compounds &Their Interactions with WaterTheir Interactions with Water
• Polar molecules that can interact favorably with waterPolar molecules that can interact favorably with water
• Amino acids have both an amino and a carboxylic acid Amino acids have both an amino and a carboxylic acid group, which are polar.group, which are polar.
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Biochemical Compounds &Biochemical Compounds &Their Interactions with WaterTheir Interactions with Water
• Nonpolar molecules that cannot interact favorably with Nonpolar molecules that cannot interact favorably with waterwater
• The carboxylic acid groups, though polar, are dominated by The carboxylic acid groups, though polar, are dominated by the long hydrocarbon portions the long hydrocarbon portions
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Biochemical Compounds &Biochemical Compounds &Their Interactions with WaterTheir Interactions with Water
•A nonpolar solute "organizes" water•The H-bond network of water reorganizes to accommodate the nonpolar solute•This is an increase in "order" of water-This is a decrease in ENTROPY
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Biochemical Compounds &Biochemical Compounds &Their Interactions with WaterTheir Interactions with Water
CH4 in benzene→ CH4 in water -2.8 -18 +2.6CH4 in ether→ CH4 in water -2.4 -19 +3.3CH4 in CCl4→ CH4 in water -2.5 -18 +2.9C3H8 liquid→ C3H8 in water -1.8 -23 +5.1
Recall ΔG=ΔH-TΔS
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Biochemical Compounds &Biochemical Compounds &Their Interactions with WaterTheir Interactions with Water
Amphipathic molecules, which are conflicted about their Amphipathic molecules, which are conflicted about their feelings towards water.feelings towards water.
• Molecules containing both very polar and very nonpolar Molecules containing both very polar and very nonpolar parts.parts.
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Biochemical Compounds &Biochemical Compounds &Their Interactions with WaterTheir Interactions with Water
When placed in water, When placed in water, amphipathic molecules, amphipathic molecules, form structures, such as form structures, such as micelles, which attempt to micelles, which attempt to address the conflict.address the conflict.
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Colloids and SuspensionsColloids and Suspensions
It is also possible to have mixtures which are not uniform at It is also possible to have mixtures which are not uniform at the molecular level.the molecular level.
• These are called These are called heterogeneous mixturesheterogeneous mixtures..
When a heterogenous mixture involves the mixing of a solid When a heterogenous mixture involves the mixing of a solid with a liquid, there are two possible situations:with a liquid, there are two possible situations:
• Suspensions:Suspensions:• With time the solid settles out of the mixtureWith time the solid settles out of the mixture
• Colloids:Colloids:• The solid stays suspended in the liquid indefinitely,The solid stays suspended in the liquid indefinitely,
Both suspensions and colloids are cloudy.Both suspensions and colloids are cloudy.
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Colloids and SuspensionsColloids and Suspensions
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Diffusion and OsmosisDiffusion and Osmosis
Within a solution, the solute and solvent molecules are Within a solution, the solute and solvent molecules are constantly movingconstantly moving
• If the concentration of the solute is not uniform throughout If the concentration of the solute is not uniform throughout a solution, this movement will cause a net movement of a solution, this movement will cause a net movement of solute molecules from the regions of high concentration to solute molecules from the regions of high concentration to the regions of low concentrationthe regions of low concentration
• In the end the concentration will be the same everywhere.In the end the concentration will be the same everywhere.
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This movement is called This movement is called diffusion.diffusion.
Diffusion and OsmosisDiffusion and Osmosis
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Diffusion and OsmosisDiffusion and Osmosis
If a If a semipermeable membranesemipermeable membrane that only allows solvent to that only allows solvent to pass through it is used to separate a region of high solute pass through it is used to separate a region of high solute concentration from a region of low solute concentrationconcentration from a region of low solute concentration
• Solvent will move through the membrane from the region of Solvent will move through the membrane from the region of low solute concentration to the region of high solute low solute concentration to the region of high solute concentration in an effort to make the solute concentration concentration in an effort to make the solute concentration the same on both sides of the membrane.the same on both sides of the membrane.
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Diffusion and OsmosisDiffusion and Osmosis
This movement is called This movement is called osmosisosmosis..
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Diffusion and OsmosisDiffusion and Osmosis
This movement can be stopped by This movement can be stopped by applying a pressure to the surface of applying a pressure to the surface of the solution on the high solute the solution on the high solute concentration side of the concentration side of the membrane.membrane.• The pressure required to stop the The pressure required to stop the
movement is called the movement is called the osmotic osmotic pressurepressure..
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Diffusion and OsmosisDiffusion and Osmosis
Osmotic pressure is an important concept for understanding Osmotic pressure is an important concept for understanding biological systems because the cell membrane is a biological systems because the cell membrane is a semipermeable membranesemipermeable membrane• If the solute concentrations are not equal on both sides of If the solute concentrations are not equal on both sides of
the membrane, the cells can either shrivel up or swell up the membrane, the cells can either shrivel up or swell up and explodeand explode
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