Molar Mass Sections 4-4 to 4-6

Carbon Atomic # is 6 Atomic mass is u Molar mass (mass per mole) is g/mole

Molar Mass Molar mass for an element is found by taking the atomic mass for that element in the periodic table and changing the units to grams/mole. Molar mass for a compound is found by adding the atomic masses (in grams) for ALL the elements in the compound.

H2OH2O -Molar mass of hydrogen is 1.01g/mole -There are two atoms of hydrogen in water -Molar mass of oxygen is 16.0 g/mole 2(1.01 g/mole) H g/mole O = g/mole H 2 O

NaCl Molar mass of sodium is g/mole Molar mass of chlorine is g/mole g/mole Na g/mole Cl = g/mole NaCl

What is the mass of 1.31 mol of silver nitrate? 1.Find the correct chemical formula for silver nitrate. silver = Ag + nitrate = NO 3 - Silver nitrate is AgNO 3

2. Find the molar mass of AgNO 3. molar mass Ag = g/mole molar mass N = g/mole molar mass O = g/mole there are three atoms of O g/mole Ag g/mole N + 3(16.00 g/mole O) = g/mole AgNO 3

3.Find the mass of 1.31 mole of AgNO 3. X g AgNO g AgNO 3 ______________ = ______________ 1.31 mole AgNO 3 1 mole AgNO 3 X = g AgNO 3

How many moles are in a 124 g sample of C 8 H 18 ? 1.Find the molar mass of C 8 H 18. molar mass C = g/mole there are 8 atoms of C molar mass H = 1.01 g/mole there are 18 atoms of H 8(12.01 g/mole C) + 18(1.01 g/mole H) = g/mole C 8 H 18

2. Find how many moles of C 8 H 18 are in grams. x moles C 8 H 18 1 mole C 8 H 18 _____________ = ____________ g C 8 H g/mole C 8 H 18 x = 1.09 moles C 8 H 18

Copy the Molar Calculator from either the poster on the wall, or from page 108 in the text book. Do practice questions on page 109 # 4-8, 10-11, These practice questions will be corrected in class on Thursday.