Calculations involving empirical formulas and molecular formulas

Feb 1 2013Objective: to learn how to find the empirical formula when the molecular formula and the experimental mass are given.Preclass: Define molecular formula, compare this to empirical formula. Give some examples of each. See page 244Agenda: 5 mins preclass15 minutes lecture20 minutes practice problems.

PbS - Galena

the molecular formula = the empirical formula of Galena

Acetic acid: Molecular formula C2H4O2Empirical formula CH2OWhat is the ratio of the molecular to the empirical?

Formaldehyde: Molecular formula: ?Empirical formula CH2O experimental mass is 30.03 grams what is the molecular formula?

Glucose: Molecular formula C6H12O6Empirical formula =

C9H18N6 is an anticancer drug called altremine. What is its empirical formula?

Benzene a known carcinogen, has molecular formula of C6H6What is its empirical formula?

Sample problem H page 245 Determine molecular formula from empirical formulaGiven: empirical formula = P2O5Molar mass = 284 g / molmolecular formula??first find molar mass of empirical formula.P2 = 2X 30.97g = 61.94 gO5 = 5 X 16.00 g = 80.00 gmolar mass of P2O5 = sum = 141.94

Sample H continued solve for n the factor multiplying the empirical formula to get the molecular formula.n= experimental molar mass molar mass of empirical formula

n = 284 g/mol 141.94 g/mol = 2

Objective: To review problems from Chapter 7 for quiz on chapter 7 next week on Thursday. Do now the problem assigned to you on the paper I give you. Do these 4 problems now. They will be graded as a quiz.You must show all the work. Page 253 # 60, #62, 65, 70aBonus: For one of your problems explain completely how you did one of them.

Multiply the empirical formula by this number to get the molecular formula.

2 (P2O5) = P4O10

Try page 245 # 1,2,3,

N2O4 is the molecular formula for dinitrogen tetroxide. It is a rocket propellant but it is also found in smog. What is its empirical formula?

Iso octane has a molecular formula of C8H18 what is its empirical formula?

10 period HomeworkPage 254 # 65 - 69 please show all the work. For the first problem explain all the steps you are taking.

2013 January Chapter 7Objective: Be able to find the molecular formula from an empirical formula and the mass of the molecular formula. Preclass: Calculate the molar mass of each of these compounds: H2O CO2 Fe2(SO4)3

Exit ticket: With the person next to you, make a Frayer model for one of these vocabulary words. Molar mass, empirical formula, mole, or percentage composition

Molar mass, empirical formula, mole, or percent composition, Frayer model definition characteristics

examples non examples

Definition Characteristics

Examples non Examples word