molarity and dilution

Solutions:

When table salt is mixed with water, it seems to

XX or become a XX; the mixture is

XX.

• The salt is still there, as you can tell from the taste or

simply boiling away the water.

• Homogeneous mixtures are called XX

• The majority component is the XX

• The minority component is the XX.

• A solution in which water is the XX is an

aqueous solution

When table salt is mixed with water, it seems to

disappear or become a liquid; the mixture is

homogeneous.

• The salt is still there, as you can tell from the taste or

simply boiling away the water.

• Homogeneous mixtures are called solutions.

• The majority component is the solvent.

• The minority component is the solute.

• A solution in which water is the solvent is an

aqueous solution

Solution concentration:

Because solutions are XX, the XX

can vary from one sample to another.

• Pure substances have XX XX.

• Saltwater samples from different seas or lakes have

XX amounts of XX.

• So, to describe solutions accurately, we quantify

the amount of solute relative to solvent, or

concentration of solution.

Concentration = XX of XX/ .

amount of XX(or XX)

Because solutions are mixtures, the composition

can vary from one sample to another.

• Pure substances have constant composition.

• Saltwater samples from different seas or lakes have

different amounts of salt.

• So, to describe solutions accurately, we quantify

the amount of solute relative to solvent, or

concentration of solution.

Concentration = amount of solute .

amount of solution (or solvent)

Solution Concentration

• Solutions are often

described quantitatively,

as XX or XX

• Dilute solutions have a

XX amount of XX

compared to solvents.

• Concentrated solutions

have a XX amount of

XX compared to

XX

Solution Concentration

• Solutions are often

described quantitatively,

as dilute or concentrated.

• Dilute solutions have a

small amount of solute

compared to solvents.

• Concentrated solutions

have a large amount of

solute compared to

solvents

Solution Concentration: Molarity

A common way to express solution concentration is molarity (M).

• Molarity is the amount of solute (in moles) divided by the volume of

solution (in liters)

M=MOL/L

Solution Concentration: Molarity

A common way to express solution concentration is molarity (M).

• Molarity is the amount of solute (in moles) divided by the volume of

solution (in liters)

M=MOL/L

Solution Dilution:

• Often, solutions are stored as concentrated

stock solutions.

• To make solutions of lower concentrations from

these stock solutions, more solvent

is added.

- The amount of solute doesnʼt change, just the

volume of solution:

moles solute in solution 1 = moles solute in solution 2

• The concentrations and volumes of the stock and

new solutions are inversely proportional: XX∙XX =XX∙XX

• Often, solutions are stored as concentrated

stock solutions.

• To make solutions of lower concentrations from

these stock solutions, more solvent

is added.

- The amount of solute doesnʼt change, just the

volume of solution:

moles solute in solution 1 = moles solute in solution 2

• The concentrations and volumes of the stock and

new solutions are inversely proportional:

M1∙V1 = M2∙V2

Titrations

• Titration: careful XX of a solution of known concentration to a

solution of unknown concentration until the XX is complete.

• The solution of known concentration is called the XX XX.

• The volume of the standard solution and the volume (or mass) of the

sample solution are both carefully measured.

• The mole ratio is used to calculate the concentration of the sample.

• Equivalence Point: when both XX have reacted XX

• Indicators: are substances that change XX near an XX point.

Titrations

• Titration: careful addition of a solution of known concentration to a

solution of unknown concentration until the rxn is complete.

• The solution of known concentration is called the standard solution.

• The volume of the standard solution and the volume (or mass) of the

sample solution are both carefully measured.

• The mole ratio is used to calculate the concentration of the sample.

• Equivalence Point: when both reactants have reacted completely.

• Indicators: are substances that change color near an equivalence

point.

Solution stoichiometry:

Because molarity relates the moles of solute to the

liters of solution, it can be used to convert between

amount of reactants and/or products in a chemical

reaction.

• In these problems, the amount of products or

reactants is given in X.

XX X→X(in moles)→Amount B(in moles)→Volume B

Solution stoichiometry:

Because molarity relates the moles of solute to the

liters of solution, it can be used to convert between

amount of reactants and/or products in a chemical

reaction.

• In these problems, the amount of products or

reactants is given in X.

Volume A→Amount A(in moles)→Amount B(in moles)→Volume B