Chemical Formulas Equations Molar Mass Atomic Mass 1

Chemical Formulas & Equations Molar Mass (Atomic Mass) 1

Molar Mass The molar mass: Is the mass of one mole of an element or compound Is the Atomic Mass expressed in grams (found on the periodic table!) Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings 2

Molar (Atomic) Mass from Periodic Table Molar mass is the atomic mass (AMU) expressed in grams… This Mass is located below the Element Symbol on the periodic table 1 mole Ag = 107. 9 g 1 mole C = 12. 01 g 1 mole S = 32. 07 g 3

Learning Check Give the molar (atomic) mass for each (to the tenths decimal place) A. 1 mole K atoms = ____ B. 1 mole Sn atoms = ____ C. 1 mole Pb atoms = ____ 4

Formula Mass of a Compound The formula mass of a compound is the sum (total) of the molar masses of all of the elements in the formula Example: Calculate the molar mass of Ca. Cl 2 Element Ca Number Atomic Mass of Moles 1 40. 1 g/mole Cl 2 Ca. Cl 2 35. 5 g/mole x 2 Total Mass 40. 1 g 71. 0 g 111. 1 g 5

Formula Mass of K 3 PO 4 Calculate the molar mass of K 3 PO 4. Element Number of Moles K 3 Atomic Mass P 1 31. 0 g/mole O 4 16. 0 g/mole 39. 1 g/mole Total Mass in K 3 PO 4 6

Formula Mass of a Compound Containing multiples of a Polyatomic The formula mass of a compound is the total of the molar masses of all of the elements in the formula –and a Polyatomic in the formula – in parenthesis followed by a subscript - means the entire Polyatomic is multiplied by that number Example: Calculate the molar mass of (NH 4)2 CO 3 (NH 4) is multiplied by 2! 2 Nitrogens 8…Hydrogens 7

Formula Mass of a Compound Containing multiples of a Polyatomic Example: Calculate the molar mass of (NH 4)2 CO 3 Element N Number of Moles 2 H 8 C 1 O 3 (NH 4)2 CO 3 Atomic Mass Total Mass 8

Formula Mass of Mn 3(PO 4)4 Calculate the molar mass of Mn 3(PO 4)4. Element Mn Number of Atomic Mass Moles Total Mass in Mn 3(PO 4)4 P O Mn 3(PO 4)4 9

Some One-mole Quantities One-Mole Quantities 32. 1 g 55. 9 g 58. 5 g 294. 2 g 342. 2 g 10

Learning Check What is the molar mass of each of the following formulas? A. K 2 O B. Al(OH)3 C. (NH 4)3 PO 4 11

Learning Check Prozac, C 17 H 18 F 3 NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac? 1) 40. 1 g/mole 2) 262 g/mole 3) 309 g/mole 12