Chapter 8 Solutions

5% glucose and 0.9%saline solutions are usedin IV therapy

Understanding solutionproperties help in solving environmental problems.

All of the following are solutions except:

a.airb.steelc.vinegard.milke.bleach

Do you really know what a solution is?

It is a homogeneous mixture ctg. one or more solutes dissolved in a solvent.

What is a solution?

Solid K2Cr2O7 will be the solute and waterwill be the solvent .

This is a potassium dichromate solution.

Types of Solutions

Solutions: Physical States

Solid Liquid Gas(brass) (bleach) (air)

Brass is a homogeneous solution. Granite is a heterogeneous

mixture.

What is the major solute in bleach?

What is the solvent?

O2 is the major solute and N2 is the solvent in air.

Example: Air is a gaseous solution.

Classification of Liquid Solutions

Unsaturated Saturated Supersaturated

ConcentratedDilute(tend to be opaque)(transparent)

(maximum solute) (the maximum limit is exceeded)

(less than maximum solute)

Bleach ( ~ 5% NaOCl)

Vinegar ( ~ 5% CH3COOH)

Peroxide ( ~3% H2O2)

Most household products are unsaturated dilutesolutions.

08_T01.JPG

Tests for a Solution

Liquid solutions can pass the following tests:

(a) Can pass thru a filter with no residue

(b) Does not scatter a light beam

(c) Does not form a ppt when centrifuged ( i.e.particles do not settle)

(d) Dilute solutions have a clear/uniform appearance

Tests for a Solution

p. 193

Solutions leave noresidue when filtered.

Light is not scatteredby a solution

Dilute solutions are clear.

Practice Exercises on Solutions

Is the contents of the coke bottle asolution?

p. 193

Is the beer as shownin this mug a solution?

p. 192

Is the mixture in the beaker a solution?

p. 200

Whole Blood

Is this a solution?

p. 200

Blood is not a solution .

p. 207

Are these sports drinks solutions?

Are these solutions?

Flask A Flask B

Is this a solution?

Is this mixture of water and ether a solution?

Is gasoline a solution?

Practice Exercise on Differentiatingthe Solute and the Solvent

Solution Solute Solvent

10.0 g of potassium chloride

dissolved in 70.0 g of water

80.0 g of ethyl alcohol

added to 50.0 g of water

60.0 g of CaBr2 and 25.0 g of AgNO3 dissolved in 100.0g of water

40.0 mL of ethanol dissolved in 40.0 mL of methanol.

Common Types of Solutions

Error Check: True or False?

All solutions are homogeneous mixtures

Every part of a solution has exactly the same properties as every other part

All solutions have a variable composition.

Electrolytes ( We get to this on Wed)

Solubility

What vitamins arewater soluble?

What vitamins are fat-soluble?

What is solubility ?

Solubility is the grams of solute per 100g of H2O at 25C

Solubility is affected by:

•Temperature

•Polarity of the solvent and solute

•Particle size of the solute

•Pressure when gases are involved

Effect of Temperature on Solubility (Solids)

Effect of Polarity

“ like dissolves like”

Polar solutes prefer polar solvents ….

..and the same for nonpolar solutes/solvents

What does “like dissolves like” mean?

Predict the solubility of CH3COOH in H2O

a.Very solubleb.Moderately solublec.Slightly solubled.Insoluble

Effect of Polarity

CH3COOH (acetic acid)is the active ingredient in vinegar… it is very solublein H2O.

Effect of Polarity

Predict the solubility of oil (CnH 2n +2) in H2O

a.Very solubleb.Moderately solublec.Slightly solubled.Insoluble

Effect of Polarity

Predict the solubility of CH3CH2OCH2CH3

in H2O

a.Very solubleb.Moderately solublec.Slightly solubled.Insoluble

Gasoline and water are not miscible. Why?

Gasoline is nonpolar and water is polar.

Solubility Rules

Solubility Rules

p. 193

Practice Exercise: Identify the solublecompound(s) in each set.

1.KHCO3, K2CO3, KOH, KI, K3PO4

2. Ba(OH)2, BaSO4, BaCO3, Ba(NO3)2

3.NaCl, AgCl, BeCl2, CuCl2

4.NH4NO3, PbSO4, AgNO3, Ni(OH)2

What is the effect of temperature and pressure on gas solubility?

Effect of Temperature on Solubility (Gases)

Effect of Pressure on Solubility (Gases) (Henry’s Law)

Henry’s law states:

The solubility of a gas is proportional to its partial pressure .

Effect of Pressure on Solubility of Gases (Henry’s law)

Start End Increase Pressure

How would Henry’s Law apply in the case of the blood gases in deep-sea divers.

Solubility increases with higher pressure and vice-versa.

Pressure and the Solubility of Gases (Henry’s law)

Pressure (atm)

Solubility of CO2

( g/100mL water)

1 0.348

2 0.696

3 1.044

Solution Formation

How does an ionic compound dissolve in water?

NaCl(s) Na+(aq) + Cl (aq)Add H2O

s = solidaq = aqueous

Start

NaCl Dissolving in H2O

Halfway End

The ions become hydrated by the water molecules.

A hydrated ion is an ion surrounded by H2Omolecules.

This is a hydrated Na+ ionThis is a hydrated Cl- ion.

The rate of solution formation is determined by:

(a)Particle size

(b)Temperature

(c) The amount of agitation

Preparing Solutions of Known Concentrations

Volumetric flasks are used to prepare solutions.

Concentrations are defined as the amountof solute dissolved in an amount of solution

Solution Concentrations

PercentMolarity

volume percentmass percent mass-volume percent

Percent Concentrations

Mass/Mass Example

Prepare 225g of a 6.00 %(m/m) KCl solution

%(m/m) = g solute

g solution

x 100

Reminder: solution = solute + solvent

Prepare 225g of a 6.00 %(m/m) KCl solution

6% = ?g solute

225g solution x 100

Mass/Volume Example

How many grams is required to prepare 250.0 mL of a 12.0% (m/v) glucose solution.

Practice Exercise—Percent : How many gramsor mL are needed to make the following solutions?

200.0 mL of 0.8%(m/v) NaOH

300.0 mL of 34.0% (v/v) methanol CH3OH

150.0 g of 2.5% (m/m) KOH

Molarity is an important concentration used in the chemistry lab.

M ( molarity ) = mol (moles of solute)

L ( liters of solution)

For example, what is does a 3.0 M HCl solution mean?

What does a 0.1M AgNO3 solution mean?

Practice Exercise—Molarity : How many moles are needed to make the following solutions?

1 L of 4.0 M NaOH

250 mL of 3.5 M KI

Start morning2.0 L of 3.5 M CaCl2

Practice Exercise—Molarity : How many grams are needed to make the following solutions?

1 L of 4.0 M NaOH

250 mL of 3.5 M KI

2.0 L of 3.5 M CaCl2

Write a brief set of instructions for preparing250 mL of a 6.8% (m/v) glucose solution.

relax and get organized

write the correct formula

use the formula toget the g of solute

write the instructions

1 2 3

4

The grams of glucose required is 17 grams.

In a 250-mL volumetric flask dissolve 17 g of glucose in d.w. and dilute to the mark. Mix well.

Note: Volumes are not equal when mixing different liquids.

Can the marbles fit in the large beaker?

Preparing Dilute Solutions

Start with a “stock solution:

Dilute Solution Formula

concentration of stock solution x volume of

stock solutionconcentration of diluted solution= x volume of

diluted solution

xCs Vs = xCd Vd