Solutions

Dr. Ron RusayDr. Ron Rusay

Spring 2003Spring 2003

Limestone Caves: Solubility of CaCO3

Solutions

Substances can mix together to form Substances can mix together to form homogeneous mixtures (homogeneous mixtures (solutionssolutions). The material ). The material present in the larger amount is the present in the larger amount is the solventsolvent and and the other(s) is (are) the the other(s) is (are) the solute(s).solute(s). Together they Together they form a solution. form a solution.

The most common solutions are liquids. The The most common solutions are liquids. The solute can be a solid, liquid or gas which is solute can be a solid, liquid or gas which is dissolved in a liquid solvent.dissolved in a liquid solvent.

The most common solvent is water.The most common solvent is water.

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© Copyright 1995-2001 R.J. Rusay© Copyright 1995-2001 R.J. Rusay

DHMO, dihydromonoxide : “The Universal” Solvent

04_40

H

O2δ−

δ+

δ+

105 °

H

http://www.dhmo.org

Water as a Solvent

04_40

H

O2δ−

δ+

δ+

105 °

H

Generally, likes dissolve likes, i.e. polar-polar and nonpolar-nonpolar. If polar and nonpolar mix , eg. oil and water:

The oil (nonpolar) and water (polar) mixture don’t mix and are immiscible. If liquids form a homogeneous mixture, they are miscible.

Salt dissolving in a glass of water

Water dissolving an ionic solid

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Concentration and Temperature

Besides amount, the rate also increases. What are two other ways of increasing the solubility of a solid, eg. sugar in coffee?

Relative SolutionConcentrations:SaturatedUnsaturatedSupersaturated

Solution Types Solutions with less solute dissolved than is Solutions with less solute dissolved than is

physically possible are referred to as physically possible are referred to as ““unsaturatedunsaturated”. Those with a maximum ”. Those with a maximum amount of solute are “amount of solute are “saturatedsaturated”.”.

Occasionally there are extraordinary Occasionally there are extraordinary solutions that are “solutions that are “supersaturatedsupersaturated” with ” with more solute than normal.more solute than normal.

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A Giant, Single Crystaland Nuclear Energy

Tooth Enamel (Dentyne) & Fluoride Treatment

Gas Solubility

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Solubility @ P2 = Solubility @ P1 x [P2 / P1 ]P is the partial pressure of the gas vapor.

Solubility units (Concentration) are usually: g / 100 ml

Preparation of Solutions

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Solution Concentration

A solution’s concentration is the measure of the A solution’s concentration is the measure of the amount of solute dissolved. amount of solute dissolved.

Concentration is expressed in several ways. One way Concentration is expressed in several ways. One way is mass percent.is mass percent.

Mass % = Mass solute / [Mass solute + Mass solvent ] Mass % = Mass solute / [Mass solute + Mass solvent ] x100x100

What is the mass % of 65.0 g of glucose dissolved in What is the mass % of 65.0 g of glucose dissolved in 135 g of water?135 g of water?

Mass % = Mass % = 65.0 g / [65.0 + 135]g x10065.0 g / [65.0 + 135]g x100

= 32.5 % = 32.5 %

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Solution Concentration Concentration is expressed more importantly as Concentration is expressed more importantly as

molarity molarity (M)(M)..

Molarity (M) = Moles solute / LiterMolarity (M) = Moles solute / LiterSolutionSolution

An important relationship is An important relationship is M x VM x Vsolutionsolution= mol= mol This relationship can be used directly in mass This relationship can be used directly in mass

calculations of chemical reactions.calculations of chemical reactions. What is the molarity of a solution of 1.00 g KCl in What is the molarity of a solution of 1.00 g KCl in

75.0 mL of solution?75.0 mL of solution?M =M = 1.00g 1.00g KClKCl x 1mol x 1mol KClKCl / 74.55 g / 74.55 g KCl KCl x 1/ 75mL x 1000mL / Lx 1/ 75mL x 1000mL / L

= 0.18 mol / L= 0.18 mol / L

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© Copyright 1995-2001 R.J. Rusay© Copyright 1995-2001 R.J. Rusay

Acid-Base Titration

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Solution ApplicationsSolution ApplicationsNeutralization-TitrationNeutralization-Titration

15.5015.50 mL of vinegar, a solution of acetic acid (aa), mL of vinegar, a solution of acetic acid (aa), required required 20.0020.00 mL of a mL of a 0.30000.3000 M (mol/L) M (mol/L) solution of a sodium hydroxide solution to react solution of a sodium hydroxide solution to react completely. completely. MMaaaa = ? = ?

HCHC22HH33OO2 2 (aq)(aq) + NaOH + NaOH(aq)(aq) ? + ? ? + ?

HCHC22HH33OO2 2 (aq) + NaOH(aq) (aq) + NaOH(aq) 11 NaC NaC22HH33OO22 (aq) + (aq) + 11HH22O (l)O (l)

??MMaaaa = [MNaOHx VNaOH / VHC2H3O2HC2H3O2 ] [? ] [? molmolHC2H3O2HC2H3O2 / ? / ? molmolNaOHNaOH]]

0.3000 molNaOH x 0.02000 LNaOHNaOH x 11 molmolHC2H3O2HC2H3O2

LLNaOHNaOH x 0.01550 0.01550 LLHC2H3O2HC2H3O2 x 11 molmolNaOHNaOH

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??MMaaaa =

??MMaaaa = 0.3870 0.3870 molHC2H3O2HC2H3O2 / L/ LHC2H3O2HC2H3O2 = 0.3870 0.3870 MHC2H3O2HC2H3O2

Solution ApplicationsSolution Applicationshttp://ep.llnl.gov/msds/Chem106/vinegar.html

What is the weight percent of the acetic acid What is the weight percent of the acetic acid (aa)? (aa)?

((Density of vinegar = 1.006 g/mL; Molar Mass (aa) = MW (aa) in grams/ mole aa = 60.056g aa/mole aa)

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� (Molarity aa x Volume aa) x (60.056g aa /mole aa)(Molarity aa x Volume aa) x (60.056g aa /mole aa)� = mass aa= mass aa == 0.3600.360 g gaaaa

[(mass of Acetic Acid) / (mass of vinegar) ] * 100% = % [(mass of Acetic Acid) / (mass of vinegar) ] * 100% = % Acetic Acid Acetic Acid

� mass of vinegar = density x sample volume = mass of vinegar = density x sample volume = 15.59 15.59 gg

� % = % = 0.3600.360 g gaa aa / / 15.59 15.59 g g * 100 = * 100 = 2.3%2.3%

Solution Dilution

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