Presentation on theme: "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."— Presentation transcript:
1 mole = 6.02 x 10 23 atoms, molecules, ions, formula units A.k.a. Avogadro’s Number 1 mole of a substance contains 6.02 x 10 23 representative particles
Representative particle: refers to the species present in a substance: atoms, molecules, ions Substance Rep. Particle Formula R.P. in 1 mol Atomic N AtomN 6.02 * 10 23 Nitrogen Gas Molecule N2N2N2N2 6.02 * 10 23 WaterMolecule H2OH2OH2OH2O Calcium ion Ion Ca +2 6.02 * 10 23 Calcium flouride Formula unit CaF 2 6.02 * 10 23 SucroseMolecule C 12 H 22 O 11 6.02 * 10 23
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 (C 3 H 8 )?
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 CO 2
Grams A 1 mole A = mole A gfm A Mole B gfm B = gfm B 1 mole B conversions
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: 0 o C 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
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 (C 3 H 8 ).
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?