Chemical Quantities

Ways to measure matter: Count how many of something you

have Weigh it (or mass it) Volume

Units that refer to a specific # pair = 2 dozen = 12

1 mole = 6.02 x 1023 atoms, molecules, ions, formula unitsA.k.a. Avogadro’s Number

1 mole of a substance contains 6.02 x 1023 representative particles

Representative particle: refers to the species present in a substance: atoms, molecules, ions

SubstanceSubstance Rep. ParticleRep. Particle FormulaFormula R.P. in 1 molR.P. in 1 mol

Atomic NAtomic N AtomAtom NN 6.02 * 106.02 * 102323

Nitrogen GasNitrogen Gas MoleculeMolecule NN22 6.02 * 106.02 * 102323

WaterWater MoleculeMolecule HH22OO 6.02 * 106.02 * 102323

Calcium ionCalcium ion IonIon CaCa+2+2 6.02 * 106.02 * 102323

Calcium Calcium flourideflouride

Formula unitFormula unit CaFCaF22 6.02 * 106.02 * 102323

SucroseSucrose MoleculeMolecule CC1212HH2222OO1111 6.02 * 106.02 * 102323

How big is one mole?One mole of sand would cover L.A.

to a depth of 600 meters (1,968 ft)

Marbles would cover the earth to a depth of 40 miles

Propane is a gas used for cooking and heating. How many atoms are in 2.12 mol of propane (C3H8)?

Atomic mass unit of all elements are based off the Carbon – 12 atom

The atomic mass of an element expressed in grams is the mass of a mole of the element

How many atoms are in one mole of magnesium?

To calculate the molar mass of a compound, find the number of grams of each element in one mole of the compound. Then add the masses of the elements in the compound

What is the molar mass of CO2

Grams A 1 mole A = mole A gfm A

Mole B gfm B = gfm B 1 mole B

conversionsconversions

Avogadro’s Hypothesis – equal volumes of gases at the same temperature and pressure contain equal numbers of particles

Standard temperature and pressure – (STP)

Standard temp: 0oC pressure: 101.3 kPa or 1 atm

@ STP 1 mole of gas occupies 22.4 L

22.4 L = molar volume of a gas @ STP

END of Part 3

Molar mass = density @ STP x molar volume @ STP

The density of a gas containing Carbon and Oxygen is found to be 1.946 g/L @ STP. What is the molar mass of the compound?

The relative amounts of the elements in a compound are expressed as percent composition

The percent by mass of an element in a compound - the number of grams of the element divided

by the mass in grams of the compound...multiplied by 100%.

Calculate the percent composition of Carbon and Hydrogen in propane (C3H8).

Empirical formula: gives the lowest whole number ratio of the atoms of the elements in a compound

What is the empirical formula of a compound that is 67.6% mercury, 10.8% sulfur and 21.6% oxygen?

What is the empirical formula of a compound that is 25.9% nitrogen and 74.1% oxygen?

END of Part 4