Solution Chemistryexternal image chemistry-stuff.jpg


Editor- Marybeth Nametz

Solution/Acid Base Vocabulary

Aqueous Solution: Solution in water

Boiling Point Elevation: Phenomenon that occurs when the boiling point of a solvent is increased when another compound is added causing that solution to have a higher boiling point than the pure solvent. Occurs whenever a non-volatile solute is added to a pure solvent

Brownian Movement: The random motion of small particles suspended ina gas or liquid

Colligative Properties: Properties of solutions that depend on the number of molecules in a given volume of solvent and not on the properties of the molecules

Colloid: A mixture whose particles are intermediate in size between those of a suspension and a solute solution

Concentrated Solutions: A solution that contains a large amount of solute relative to the amount that could dissolve

Concentration: The abundance of a constituent divided by the total volume of a mixture

Dilute Solutions: A solution that has a small amount of solute compared to the amount of solvent

Electrolyte: Any substance containing free ions that make the substance electrically conductive

Emulsion: A fine dispersion of minute droplets

of one liquid in an other in which it is not soluble or miscible

Freezing point depression: The difference in temperature between the freezing point of a solution and the freezing point of a pure solid

Henry's law: A law formulated by the English chemist William Henry; the amount of a gas that will be absorbed by water increases as the gas pressure increases

Hydrate: A compound that has a specific nubmer of water molecules bound to each formula unit

Immiscible: Describes liquids that are insoluble in one another; oil and water are immiscible

Molality: The concentration of solute in a solution expressed as the nuimber of moles of solute dissolved in 1 liter of solution

Mole Fraction: The ratio of the numbe rof moles of a substance in a mixture or solution to the total number of moles

Nonelectrolyte: A compound that does not conduct an electric current in aqueous solution or in the molten state

Saturated Solution: A solution in which the maximum amount of solvent has been dissolved

Solubility: The amount of a substance that dissolves in a given quantity of solvent at specified conditions of a temperature and pressure to produce a saturated solution

Solute: Dissolved particles in a solution

Solvation: A process that occurs when an ionic solute dissolves; in a solution, the solvent molecules surround the positive and negative ions

Solvent: The liquid in which a solute is dissolved to form a solution

Strong Electrolyte: A solution in which a large portion of the solute exists as ions

Supersaturated Solution: A solution that contains a highter than saturation concentration of solute; slight disturbance or seeding causes crystallizat

ion of excess solute

Surface Tension: The elasticlike force existing in the surface of a body (esp. liquid) tending to minimize the area of the surface

Surfactant: A substance that tends to reduce the surface tension of a liquid in which it is dissolved

Suspension: A heterogenous mixture in which solute-like particles settle out of solvent-like phase some time after their introduction

Tyndall effect: Light scattering by particles in a colloid or particles in a fine suspension

Unsaturated Solution: In physical chemistry, saturation is the point at which a solution of a substance can dissolve no more of that substance and additional amoutns of it will appear as a precipitate

Weak Electrolyte: A material which, when dissolved in water, gives a solution that conducts only a small electrice current

Group 1: Water and Its Properties (pgs. 445-449)

Hannah Valley

Water in the Liquid State

  • water is a simple triatomic molecule H2O
  • the oxygen atom forms a covalent bond to hydrogen atoms
  • oxygen becomes negative
  • polar molecules are atracted to eachother by dipole interactions, one negative and one positive end connectSu
Surface Tension
  • the inward force that minimizes the surface area of a liquid is surface tension
  • and substance that interferes with hydrogen bonding between molecules, resulting in surface tension is the surfactant
Vapor Pressure
  • hydrogen bonding between molecules explains why water has an unusually low water vapor temperature
  • hydrogen bonds hold water molecules to one another, so the tendency of them to escape is low and it evaporates slowly
Water in the Solid State
  • water in solid state happens when it reaches a certain temperature (32 F, 0 C)
  • at 4 C, water no longer behaves like a liquid because the density starts to decrease
  • the structure of ice is a regular open framework of water molecules arranged like a honeycomb
  • ice floating is because when it freezes, it is less dense than when liquid so, less dense than liquids is could be in

Group 2: Homogeneous Aqueous Systems (pgs. 450-458)

Emily Taylor

Solvents and Solutes

  • An aqueous solution is water that contains dissolved substances.

  • A solvent is the dissolving medium.

  • A solute is the dissolved particles.

  • A solvent dissolves the solute. The solute becomes dissolved in the solvent.

  • Ionic compounds and plar covalent molecules dissolve best in water.

The Solution Process

  • As individual solute ions break away from the crystal, the negatively and positively charged ions become surrounded by solvent molecules and the ionic crystal dissolves.

  • Solvation is the process by which the positive and negative ions of an ionic solid become surrounded buy solvent molecules.

  • Water and oil don't mix.

Electrolytes and Nonelectrolytes

  • An electrolyte uis a compound that conducts an electric current when it is in an aqueous soluition or in the molten state.

  • All ionic compounds are electrolytes because they diccociate into ions.

  • A nonelectrolyte is a compound that doesn't conduct an electric current in either queous solution or the molten state.

  • Sodium chloride is a strong electrolyte.

  • A weak electrolyte conducts elecricity poorly because only a fraction of the solute in the solution exists as ions.

Hydrates

  • A compound that contains water of hydration.

  • In writing a formula for a hydrate, use a dot to connect the formula of the compound and the number of water molecules per formula unit.

  • Efflorescent Hydrates are anything coated with a white powder, such as baking soda, or sodfium carbonate decahydrate.

  • Hygroscopic Hydrates are hydrated salts that have a love vapor pressure.

  • Deliquescent Compounds can remove liquid from the air.

external image 300px-SodiumHydroxide.jpg

These sodium hydroxide pellets will absorb any liquid in the air and form a solution.

Photo: Emily Taylor
Source:
http://www.google.com/imgres?imgurl=http://soapmakingsite.com/wp-content/uploads/2009/12/300px-SodiumHydroxide.jpg&imgrefurl=http://www.soapmakingsite.com/uncategorized/basic-ingredients-in-soap-making/&usg=__cedSRb_uBbE_NrYrUdlbL8hlLD0=&h=238&w=300&sz=17&hl=en&start=0&zoom=1&tbnid=pSaqdwo-L-ArjM:&tbnh=166&tbnw=217&ei=ohPsTaWCBIL4gAfz8ZzZCQ&prev=/search%3Fq%3Dsodium%2Bhydroxide%2Bpellets%26um%3D1%26hl%3Den%26sa%3DX%26rls%3Dcom.microsoft:en-us:IE-SearchBox%26biw%3D1053%26bih%3D477%26tbm%3Disch&um=1&itbs=1&iact=rc&dur=78&page=1&ndsp=8&ved=1t:429,r:5,s:0&tx=-87&ty=-106


Group 3: Heterogeneous Aqueous Systems (pgs. 459-463)

Kelsey Sullivan

Suspensions:

  • suspensions are mixtures from which particles settle out upon standing

  • particles of a suspension are very large and do not stay suspended indefinetly

  • suspensions are heterogeneous


Colloids:

  • Colloids are heterogeneous mixtures containing particles that differ in size

  • The particles are spread throughout the dispersion medium

  • Colloids include gelatin, paint, aerosol sprays and smoke

  • Colloids have particles smaller than those in suspension and larger than those in solutions

external image placeholder?w=200&h=50
http://boomeria.org/chemlectures/solutions/solutions.html picture by Marybeth Nametz

The Tyndall Effect:


  • The tyndall effect is the scattering of visible light by colloid particles

Brownian Motion:

  • The chaotic movement of colloidal particles


Coagulation:

  • Some colloidal particles become positively charged by absorbing positively charged ions

  • Some colloidal particles become negatively charged by absorbing negatively charged ions


Emulsions:

  • A colloidal dispersion of a liquid in a liquid


Group 4: Properties of Solutions (pgs. 471-479)

Grayce Rose

Solution Formation:

  • the compositions of the solvent and the solute determine whether a substance will dissolve

  • stirring, surface area, and temperature determine how fast a substance will be dissolve

Solubility:

  • a saturated solution contains the maximum amount of solute for a given amount of solvent at a constant pressure and temperature

  • solubilityis the amount of solute that dissolves in a given amount of solvent at a standard temperature and pressure

    • it is often expressed in grams of solute per 100g of solvent

  • an unsaturated solution contains less solute than a saturated solution at a given temperature and pressure

  • two liquids are miscible if they dissolve in each other at all proportions

  • immiscible liquids are insoluble in eachother

Factors Affecting Solubility:

  • temperature affects the solubility of gas, liquid, and solid solutes in a solvent

    • both temperature and pressure affect the solubility of gaseous solute

  • a supersaturated solution contains more solute than it can theoretically hold at a given temperature.

  • Changes in temperature usually have a significant effect on the solubility of a solid substance

  • Changes in pressure have little effect on the solubility of solids, but it strongly effects the solubility of gases








source: http://www.youtube.com/watch?v=fZw9bxJg1ac&feature=player_detailpageby
By Grayce Rose

Group 5: Concentration of Solutions (pgs. 480-485)

Meghan Faber- pgs. 480-482

Molarity

  • Concentration of a solution is a measure of the amount of solute that is dissolved in a given quantity of solvent.

  • Dilute Solution: a solution that contains a small amount of solute

  • Concentrated Solution: a solution that contains a large amount of solute

  • Molarity: (a way to express concentration quantitatively) the number of moles of solute dissolved in one liter of solution

Molarity (M)= moles of solute / liters of (total) solution


Example:

  • One saline solution contains .90g NaCl in exactly 100mL of solution. What is the molarity of the solution?

1. Analyze:

Knowns:

  • solution concentration=.90g NaCl/100mL

  • molar mass NaCl=58.5 g/mol

Unknown:

  • solution concentration=M

*to solve, convert the concentration from g/100mL to mol/L

2.Calculate:

solution concentration= .90g NaCl/100mL x 1mol NaCl/58.5g NaCl x 1000mL/1L = .15mol/L= .15M

external image placeholder?w=200&h=50

Erika Paiva- pgs. 483-485


Making Dilutions

  • Diluting a solution reduces the number of moles of solute per unit volume, but the total number of moles of the solute stays the same.

  • Moles before the dilution are equal to the moles of solute after the dilution

  • Moles of solute = M1 X V1 = M2 X V2.

  • M1 and V1 are the molarity and volume of the initial solution and M2 and V2 are the molarity and volume of the diluted solution.


external image images?q=tbn:ANd9GcTqmBzTIVOOreuFlnRF78rP6cdXTtJHgtyBFcka-AtbHknAeLAfAA
http://water.me.vccs.edu/courses/env211/lesson8_4.htm by Marybeth Nametz

Example:

  • How many milliliters of aqueous 2.00M Mgo4 solution must be diluted with water to prepare 100.0 Ml of aqueous 0.400M MgSo4?

1. Analyze: List the known and unknowns

M1=2.00 M MgSo4

V1= x

M2= 0.400 MgSo4

V2= 100.0 mL of 0.400M MgSo4

2. Calculate: solve for the unkown

V1= M2 X V2/M1= 0.400M X 100.0 mL/2.00 M = 20.0 mL

Percent solutions

  • The concentration of a solution in a percent ca be expressed:

  1. as a ratio of the volume of a solute to the volume of the solution

  2. as a ratio of the mass of a solute to the mass of a solution.

1. Percent by volume (%(v/v)) = volume of the solute/ volume of the solution X 100%

Example:

  • What is the percent by volume of ethanol in the final solution when 85 mL of ethanol is diluted to a volume of 250 mL with water?

1. Analyze:

volume of ethanol= 85 mL

volume of solution= 250 mL

% of ethanol= X

2. Calculate:

% (v/v) = 85 mL ethanol/250 mL X 100% = 34% ethanol (v/v)

Concentration in percent (mass/mass)

  • Percent by mass 5(m/m) = mass of solute/mass of solution X 100%

  • When you use percentages to express concentration, be sure to state the units (v/v) or (m/m)

Group 6: Colliative Properties of Solutions (pgs. 487-490)

Julia McNamara- pgs. 487-488

Vapor-Pressure Lowering

  • A colligative property is a property that depends only upon the number of solute particles, and not upon their identity

  • Important collingative properties of solutions:

1. vapor pressure lowering

2. boiling point elevation

3. freezing-point depression

  • A volatile solute (i.e., a solute that has a vapor pressure of its own) will contribute to the vapor pressure above a solution in which it is dissolved. The vapor pressure above a solution containing a volatile solute (or solutes) is equal to the sum of the vapor pressures of the solvent and each of the volatile solutes.

Picture by Julia McNamara
Microscopic view of the surface of liquid water
Microscopic view of the surface of liquid water



Non-Volatile Solutes The figures below illustrate how the vapor pressure of water is affected by the addition of the non-volatile solute, NaCl. Note that:

  • there are fewer water molecules in the vapor (i.e., lower vapor pressure) above the NaCl solution than in the vapor above pure water, and
  • there are no sodium ions or chloride ions in the vapor above the NaCl solution.

Microscopic view of the surface of liquid water
Microscopic view of the surface of liquid water

Microscopic view of the surface of an aqueous NaCl solution
Microscopic view of the surface of an aqueous NaCl solution

Pure water - microscopic view.
1.0 M NaCl solution - microscopic view.
Note that the ionic solid, NaCl, produces Na+ ions (blue) and Cl- ions (green) when dissolved in water.
Volatile Solutes
The figures below illustrate how the vapor pressure of liquid xenon is affected by the addition of the volatile solute, liquid krypton.
Note that:

  • there are fewer xenon atoms in the vapor (i.e., lower vapor pressure) above the solution than in the vapor above pure liquid xenon, and
  • there are krypton atoms in the vapor above the solution (i.e., both krypton and xenon contribute to the vapor pressure above the solution).

Microscopic view of the surface of liquid xenon
Microscopic view of the surface of liquid xenon

Microscopic view of the surface of a liquid krypton-xenon solution
Microscopic view of the surface of a liquid krypton-xenon solution

Pure liquid xenon - microscopic view.
Krypton-xenon solution - microscopic view (krypton atoms are shown in blue).


Freezing-Point Depression

  • When a substance freezes, the particles of the soild take on an orderly pattern

  • Freezing point depression is when you adda solute to a liquid causes the freezing point to drop. The most common such system is the ice water bath around an ice cream maker. You start with ice and add salt. Surprisingly, as the ice melts, the temperature of the ice and the water both drop without removing any heat from the system.


    In simple terms, at 0 C, ice and water are constantly melting and freezing, just in the same amount so there is an equilibrium. If you add salt, the freezing point of the water drops but the melting point of the ice stays the same. So ice still melts but water stops freezing. As the ice melts, it absorbs heat. The interface between the ice and water will cool down first, followed by the rest of the water and ice, until the system reaches the new equilibrium temperature of -20 C (or whatever the freezing point is depressed to depending on the amount of salt added).

  • The magnitude of the freezing-point depression is proportional to the number of sloute particles dissolved in the solvent an does not depend upon their identity.

Lauren Altmeyer- pgs. 489-490

Boiling-Point Elevation

  • The temperature at which the vapor pressure of the liquid phase equals atmospheric pressure

  • The difference in temperature between the boiling point of a solution and the boiling point of a pure solvent is the boiling-point elevation

  • Colligative property Depends

  • Depends on the concentration of particles, not on their identity

  • BOILING POINT ELEVATION

  • The magnitude of the boiling point elevation is proportional to the number of solute particles dissolved in the solvent

Group 7: Colligative Properties and Calculations (pgs. 491-496)

David O'Brien-

Brendan Lynch-

Group 8: Acid Base Theories (pgs. 587-593)

Alex Fischbach- pgs. 587-590

Properties of Acids and Bases

  • Bases and acids help your body function properly

  • Acids:

    • give foods a tart/sour taste ex: vinegar, lemons (citric acid)

    • aqueous solutions of acids are electrolytes (electrolytes conduct electricity)

    • acids cause certain dyes, indicators, to change color

    • metals react with aqueous solutions of acids to produce hydrogen gas (zinc & magnesium)

    • they react with compounds containing hydroxide ions to form water and a salt

    • Acids taste sour, change the color of an acid-base indicator, and an be strong or weak electrolytes on an aqueous solution

  • Bases:

    • bitter taste

    • hazardous

    • ex: soap

    • slippery feel

    • aqueous solution of bases are electrolytes and will cause an indicator to change color

  • Arrhenius Acids and Bases

  • Acids are hydrogen-containing compounds that ionize to yield hydrogen ins in aqueous solution. Bases are compounds that ionize to yield hydroxide ions in aqueous solution.

  • monoprotic- acids that contain one ionizable hydrogen such as nitric acid

  • diprotic acids - acids that contain two ionizable hydrogens such as sulfuric acid

  • triprotic acids - acids that contain three ionizabe hydrogen compounds such as phosphoric acid

external image rxn1.gif

picture by: alexandra fischbach

Anne O'Toole- pgs. 590-593

The Bronsted-Lowry theory defines an acid as a hydrogen-ion donor, and a baseas a hydrogen-ion acceptor

  • Ammonia is a base. It is the hydrogen-ion acceptor and is a Bronsted-Lowry base. Water is the hydrogen-ion donor, and is therefore the aced

  • A conjugate acid is the particle formed when a base gains a hydrogen ion

  • A conjugate base is teh particle that remains when an acid has donated a hydrogen ion

  • A conjuage acid-base pair consists of two substances related by the loss or gain of a single hydrogen ion

  • Gilbert Lewis proposed that an acid accepts a pair of electrons during a reaction, while a base donated a pair of electrons

  • A Lewis acid is a substance that can accept a pair of electrons to form a covalent bond

  • A Lewis base is a substance that can donate a pair of electrons to form a covalent bond


external image matrix09.jpg
Photo by Anne O'Toole
http://www.meta-synthesis.com/webbook/13_lab-matrix/matrix09.jpg

Group 9: Hydrogen Ions (pgs. 594 -603)

Erin Garrity-

Self- ionization is when a water molecule reacts to become separate ions

  • In an aqueous solution, H+ and OH- are inversely proportional:

    • (1)H+ / (1) OH- = (½) H+ / (2) OH-

  • The equation that represents the formation of water molecules:

    • H+ +OH- àH20

  • H+ ion concentrations x OH- concentrations= 1.00x10 -14

  • Ion production is constant for water:

    • Kw= H+ x OH- =1.00x10 -14

  • If the H+ ion concentration is greater than the OH- concentrations then the solution is acidic

  • If the OH- concentration is greater than the H+ ion concentration then the solution is basic

The pH is the concentration of H+ ions in a solution

  • pH= -log[H+]

  • The pH range is from 0-14

  • 0 is very acidic < 7 is neutral > 14 is very basic


external image PH_scale_2.png by Marybeth Nametz
http://en.wikipedia.org/wiki/File:PH_scale_2.png

Lindsey Bedrosian-


pOH (concentration of hydroxide ions) = -log [OH-]

  • pH=14-

  • pOH=14-pH

You can find pH by:

  • kw=OH- x H+ = 1 x 10 14th

  • Kw = OH x H+

  • H+ =KW/OH = 10 14th

  • An indicator can be used to determine the pH of something by changing color

    • The color change helps give a rough estimate of pH

  • A pH meter makes rapid accurate measurements

external image acids_01.jpg
http://www.funsci.com/fun3_en/acids/acids.htm photo by Marybeth Nametz

Group 10: Strengths of Acids and Bases (pgs. 605-611)

Colleen Fitzgerald- "Strong and Weak Acids and Bases"

Stong acids and weak acids are different because strong acids completly ionize in an aqeuous solution while weak ions only ionize slightly

  • The acid dissociation constant measures how strong or weak an acid is based on how completly it will dissociate in water

  • The acid dissociation constant or Ka measures the dissociated form of an acid to its undissociated form

  • As an acid gets stronger its Ka increases and decreases when the Ka goes down

Just like strong and weak acids, there are strong and weak bases

  • Again the stronger the base the more it dissociates in an aqeuous solution

  • The base dissociation constant Kb is a ratio which compares the concentration of the acid times the concentation of the hydroxide acid to the base

  • Concentrated/strong solutions dissociate more in water then weak/diluted solutions

Video: http://www.youtube.com/watch?v=_vulYxwVFbA
external image graph2lg.gif
By:Colleen Fitzgerald

Kim Kogut- "Calculation Dissociation Constants"

To find the Ka of a weak acid or the Kb of a weak base, substitute the measured concentrations of all the substances present at equilibrium into the expressions for Ka or Kb.

  • Ka stands for acid dissociation constant and Kb stands for base dissociation constant.

  • For a weak acid, you can determine these constants if you know the initial molar concentration and the pH of the solution.

  • The formula used for finding the Ka or Kb of a substance is

Ka = [H+][A-] / [HA]


An example...


  • A 0.1000M solution of ethanoic acid is only partially ionized. From measurements of the pH of the solution, [H+] is determined to be 1.34 x 10 -3M. What is the acid dissociation constant (Ka) of ethanoic acid?

  • Knowns:

Ethanoic acid = 0.1000M

[H+] = 1.34 x 10 -3M

Ka = [H+] x [CH3COO] / [CH3COOH]

  • Substitue:
Ka = (1.34 x 10 -3) x (1.34 x 10 -3) / 0.0987

= 1.82 x 10 -5


Group 11: Neutralization Reactions (pgs. 612- 616)

Mark Cuddy- pgs. 612-613

ACID-BASE REACTIONS

  • Strong acids react with a strong base

  • Substances mixed in the same mole ratios specified by the balanced equation produce neutral solutions

Neutralzation Reactions: reactions in which an acid and a base react in an aqueous soultionto produce a salt and water

  • These reactions are one way to prepare pure samples of salts

  • The reaction of an acid with a base produce water and one of a class of compounds called salts

  • Salts are compounds consisting of an anion from an acid and a cation from a base

external image hydronium.jpg

TITRATION

  • Acids and bases sometimes, but not always, react in a 1:1 mole ratio


Equivalence Point: Happens when acids and bases are mixed and the number of moles of hydrogen ions equals the number of moles of hydoxide ions


CALCULATING TITRATION:
http://www.youtube.com/watch?v=BllRQAc76Y0&feature=related
Mark Cuddy

Abby John- pgs. 614-616

Group 12: Salts in Solutions (pgs. 618-622)

Shannon Degnan- pgs. 618-619


Salt Hydrolysis:

  • solutions of salt can be acidic, neutral, or basic

  • solutions of sodium chloride are neutral

  • ammonium chloride are acidic

  • in a pH titration the equivalence point is 7 (neutral)

  • in salt hydrolysis the cations and anions remove hydrogen ions to water

  • when salts produce acidic solutions, they contain positive ions that release protons into water

sasb.gif Shannon Degnan

Lauren Bedard- pgs. 620-622

-Ions in water have to do with the hydrolsis of the cations