Transcript Chapter 6
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 units A.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 Substance Atomic N Nitrogen Gas Water Calcium ion Calcium flouride Sucrose Rep. Particle Atom Molecule Molecule Ion Formula unit Formula N N2 H2O Ca+2 CaF2 R.P. in 1 mol Molecule C12H22O11 6.02 * 1023 6.02 * 1023 6.02 * 1023 6.02 * 1023 6.02 * 1023 6.02 * 1023 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 conversions Grams A 1 mole A = mole A gfm A Mole B gfm B = gfm B 1 mole B 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