Quantitative Chemistry

SL

SI Units

• Modern science is an international endeavour, more reliable system of standards of measure, the System International Units aka SI Units

SI Units• What’s measurement – how it is measurement - symbol

• Mass – kilogram – kg• Time – second – s• Temperature – kelvin – K • Volume – cubic metre – m3

• Pressure – pascal - Pa

Substance

• Atom – the basic unit of matter• Element – identifier of an atom• Compound – combination of two or more

atoms• Molecule – amount of atoms present for one

or more elements• Ions – amount of atoms present for one

element

Mole

• A mole is the amount of a substance which contains the same number of chemical species as there are atoms in exactly 12 grams of the isotope carbon-12.

• Symbol – mol– Ex: 1 mole of Hydrogen means one Hydrogen

atom is present

Relative Atomic Mass (Ar)

• Relative atomic mass is the mass of one mole of atoms of an element– Ex: one mole of hydrogen has a mass of 1.01g

Molecular Formula

• Composition of elements symbols to represent a molecule– Ex: H2

Relative Molecular Mass (Mr)

• Relative molecular mass is calculated by adding the relative atomic masses of the atoms making up the molecule– Ex: H2O - 18.01g

Relative Formula Mass (Mr)

• Relative formula mass is calculated by adding the relative atomic masses of the atoms making up the ionic compound– Ex: NaCl = 58.33g

Avogadro’s Number (L)

• Avogadro’s number is the number of atoms in one mole of carbon12, 12C = 12g

• L= 12.01g/ 1.99265x10-23g= 6.02x1023

– 1.99265x10-23 is mass of one carbon atom– 12.01g is mass of one mole of carbon12

• We use this number for number of atoms in one mole of an element and the number of molecules

Empirical Formula

• Empirical Formula is the simplest ratio of the elements in a chemical compound– Ex: H2O2 = HO

– Ex: C6H12O6 = CH2O

Molecular Formula

• Molecular Formula is the actual amount of elements present– Ex: Glucose• Molecular Formula = C6H12O6

• Empirical Formula = CH2O

Finding Hydrocarbon

• Hydrocarbon is any compound contain only hydrogen and carbon in its structure

• Empirical formula is CH2

• Molecular formula is CnH2n

Chemical Equation

• Chemical equation is a representation of a chemical reaction using symbols

• Reactants are the elements that will under go a chemical reaction

• Products are the elements that under went a chemical reaction

• All reactants must be present in the products to satisfy the law of conservation of matter– Ex: 2H2 + O2 2H2O

Balancing Equations

• Start with the element there is the least number of present

• Finish with the element that has the most present

Balancing Equations

• Example__CH4 + __O2 __CO2 + __H2O

1 CH4 + __O2 1 CO2 + __H2O

1 CH4 + __O2 1 CO2 + 2 H2O

1 CH4 + 2 O2 1 CO2 + 2 H2O

Mass and gaseous volume relationships in chemical reactions

• Write the equation for the reaction• Write the amounts in moles of the relevant

reactants and products of interest from the equation and show the relationship between them

• Convert the known data given into moles to find moles of the substance required

• Convert the number of moles to required quantities(mass, volume, etc…)

Mass and gaseous volume relationships in chemical reactions

• 2C2H2 + 5O2 4CO2 + 2H2O2mol 4moln(CO2) = 4 = 2:1 mole to mole ratio

n(C2H2) 2

M(C2H2) = (2x12.01) + (2x1.01) = 26.04g/mol

m(C2H2) = 1 mol = 0.0384g

26.04g/mol

Continue…M(CO2) = (12.01) + (2x15.99) = 44.00g/mol

m(CO2) = 1 mol = 0.0227g x 2 =0.0455g

44.00g/mol

Continue…1g C2H2 ? CO2

mtotal(CO2) = (44.01g/mol)x(2mol)x(1.00g)

(26.04g/mol)x(1mol)= 3.38g

Material Covered

• HL Book pages 1 - 13

Study Questions

• Ex: 1 – 13• PQ: 1 – 4 • Quiz: 1 #1-29