Ch. 10

• What is stoichiometry? The study of the quantitative relationships derived from chemical formulas and equations
• What is formula mass? The sum of the atomic masses of all atoms in a formula
• When you calculate atomic mass, what do you round to? The nearest tenths place
• What unit is atomic masses measured in? Amu
• What is molecular mass? same thing as formula mass but for covalent compounds only
• What other unit can molecular mass be displayed in? in grams, it is called gram atomic mass and gram formula mass
• What is The Mole? The amount of a compound or element that contains 6.02 x 1023 particles of that substance
• What is a mole simple definition? A bunch of atoms, because atoms are measured in bunches
• Moles of different atoms have different masses.
• One mole is how many particles? 6.02 x 1023
• What things can moles be converted to? Particles, grams, or volume
• How many particles are in a mole? What kinds of particles can it be? Avogadro's number - 6.02 x 1023; atoms, molecules, or formula units
• How do you find the number of grams for converting moles and grams? Loook at the periodic table
• What unit is used for volume? How many of these are in a mole (for a gas)? Liters - 22.4 liters in a mole
• What is precentage composition? Every compound has a certain percentage of each type of atom, which is measured by the mass of the atom
• What is the formula for percent composition? mass of element / mass of compound x 100; or part / whole x 100
• What is empirical formula? the lowest whole number ratio of atoms in a compound
• How do you find the empirical formula of an element? Divide (percents or grams) by the gram atomic massDivide the resulting numbers by the smallest of the numbers Multiply 2 or 3 if one of the numbers isn't whole
• How do you find the molecular formula of a compound? Same number of steps for the empirical formula, but then you just have to add up the total number of grams from the empirical formula, then multiply the subscript of the empirical formula by whatever your multiplied that number by to get from the total number of grams to the mw (which is given to you in the problem)