Stoichiometry

titration

determine the unknown concentration of a solution

titrant

• solution in the burette

• concentration of this solution is almost always known

• volume referred to as the ‘titre’

Neutralization Reactions

• double replacement reaction

• strong acid reacts with a strong base

• produce water and an ionic compound

Strong Acid/Strong Base Titration Curves

graph that shows the relationship between pH changing against the volume of titrant added

Analyte

• solution reacting with titrant in Erlenmeyer flask

• almost always unknown

End Point

point when there is a sudden change in some observable property of the solution

Equivalence Point

• exact theoretical chemical amount of titrant added

• pH = 7

Indicators

• Substances that change colour in solution when the acidity changes

• end point

formula solution stoichiometry

(concentration/1) x (volume/1) x (mole ratio/mole ratio) x (1/volume)

Solution Stoichiometry

procedure used to calculate quantities of solution

solution - Concentration to Concentration

(concentration / 1) x (volume / 1) x (mole ratio/mole ratio) x (1 / volume)

solution - Mass to Concentration

(grams / 1) x (1 mol / molar mass) x (mole ratio/mole ratio) x (1 / volume)

solution - Concentration to Mass

(mol / 1L) x (volume / 1) x (mole ratio/mole ratio) x (molar mass / 1)

gases

• no fixed volume/shape

• low density

• empty space between particles

• kinetic energy

gas stoichiometry

calculating the quantity of gas

Avogadro’s Law

equal volumes of all gases, at the same temperature and pressure, have the same number of molecules

Gay-Lussac’s Law

same temperature and pressure, volumes reactants and products are in simple whole numbers ratios

gases - gas → gas

volume x (mole ratio/mole ratio)

gases - mass → gas

(grams /1) x (1/ molar mass) x (mole ratio / mole ratio) x (R x temperature/pressure)

gases - Mass → gas STP

(grams / 1) x (1 / molar mass) x (mole ratio / mole ratio) x (22.7L)

gases - mass to gas SATP

(grams / 1) x (1 / molar mass) x (mole ratio / mole ratio) x (24.8L)

Theoretical Yield​

• amount of product that may be produced by a reaction under specified conditions

• from calculations

Actual Yield​

• amount of product obtained

• less than the theoretical yield

• inefficient, incomplete, difficult to collect without some loss

Percent Yield

(actual yield​/theoretical yield) x 100%

Time and Space

not all of the reactants react

Loss of Material

some of the products lost during the experiment

Contamination

not pure

wet sample

needs to be dried to not affect the mass

percent error

((actual yield - theoretical yield) / theoretical yield) x 100%

types of error

• blunder

• obeservational

• environmental

• instrumental

random error

• uncontrollable

• obeservational

• environmental

Systematic Error​

• can be fixed

• obeservational

• environmental

• instrumental

limiting reagent

• consumed first

• limiting amount of products formed

excess reagent

left over after the reaction is complete

steps limiting reactants

• balance equation for the reaction

• Calculate the moles of each reactant

• Compare the moles & find limiting reactant

finding excess reagent

subtract the amount used in the reaction from the initial amount

four steps gravimetric stoichiometry

1. balance chemical equation

2. Convert units of the given substance to moles

3. mole ratio to calculate the moles of wanted substance

4. Convert moles of the wanted substance to the desired units

Converting units to moles

(grams/1) x (1 mol/molar mass)

moles of wanted substance

(mol/1) x (mol ratio (wanted)/ mol ratio (given))

moles to desired units

(moles (given)/1) x (molar mass (wanted)/1)

gravimetric

Relating to the measurement of weight (mass) / gravity

stoichiometry

• relationship between relative quantities of substances taking part in a reaction or forming a compound

• whole integers ratio

gravimetric stoichiometry

calculating the mass of reactants and products

assumptions in stoichiometry

• spontaneous (reacts)

• quantitative - complete / full products

• fast

• stoichiometric - whole number mole ratio

ionic compounds

• dissociate in water

• charges

Net ionic equation

• balanced ionic equation

• remove spectator ions on both sides

Qualitative

• analyze chemical composition

• presence/absences of different chemical components

• distillation, extraction, color

quantitative

• quantities of different substances

• amount of different chemical components present

• titrations, mass, spectroscopy, etc.

Synthesis/formation

• 2 or more reactants combine to make 1 new product

• synthesis - polyatomic

• formation - monoatomic

Decomposition Reactions

1 reactant breaks down to form 2 or more products

Single Replacement

• single element replaces a similar element in a reactant compound

• Metals replace metals

• non-metals replace non-metals

Double Replacement

2 ionic compounds exchange ions, producing 2 new ionic compounds

Combustion Reactions

• single element or compound combines with oxygen gas

• produce carbon dioxide and water

• releasing energy

The Law of Conservation of Mass

• mass is neither created nor destroyed

• no change in mass after an isolated chemical reaction

Quantitative measurements

• solids → mass

• solutions → concentration

• gases → volumes

coefficient

moles

balancing hydrocarbons

• carbon first

• hydrogen second

• oxygen last