g of sulfuric acid = ____ molecules 2. How many atoms of O? 1.8 * molecules 7.2 * atoms Day

A chemical reaction produces 98.0 mL of sulfur dioxide gas at STP. What was the mass (in grams) of the gas produced? g SO 2

896 dL of CO 2 gas contains how many atoms? 2.4e24 molecules 7.2e24 atoms

Converting: Mass to moles Moles to mass Moles to atoms / molecules / particles Atoms / molecules / particles to moles Moles to liters Liters to moles Changing a substance = = ______________ ___________ = _____________ = ________________

Percentage Composition Mass of element Mass of compound X (100) = % element in compound … tells how much an element contributes to the mass of the compound

Percentage Composition H 2 O??? 2 H: 2 * g = g 1 O: 1 * g = g g ( g / g) X 100 = % H ( g / g) X 100 = % O

Percentage Composition An unknown compound w/ a mass of g is extracted from the roots of a plant. Decomposition of the sample produces g of C, g of O, and g of H. What is the % composition of the compound?

1) 45 L of hydrogen gas = how many grams? Day ) A sample of a compound contains g of Mg and 19 g of F. What is the percent composition of this compound (SHOW WORK)?

Empirical formula – smallest whole- number mole ratio for a compound Empirical Formulas To Calculate: 1. Convert all elements involved to moles 2. Divide all elements by the smallest # of moles 3. Obtain smallest whole #ed ratio

A compound contains 13.5 g Ca, 10.8 g O, and g H. What is the empirical formula? Empirical Formulas 1. Convert all eles. involved to moles 2. Divide all eles. by the smallest # of moles 3. Obtain smallest whole #ed ratio Ca = moles O = moles H =.675 moles Ca = mols / mols = 1 O = mols / mols = 2 H = mols / mols = 2 1 Ca : 2 O : 2 H CaO 2 H 2 Ca(OH) 2

Calculating Empirical Formulas In an unknown compound you find 4.04 g of N and g O. Empirical formula?

Empirical formula – smallest whole- number mole ratio for a compound Empirical Formulas vs. Molecular Formulas Molecular formula – actual # of atoms of each ele. in a molecular compound Sometimes But not always! the same.

Molecular Formulas To Calculate: Compare the molar mass of the empirical formula to the molar mass of the molecular formula Molecular formula – actual # of atoms of each ele. in a molecular compound

Determine the molecular formula of the compound with an empirical formula of CH and a formula mass of amu Empirical mass = g/mol x = 6 Molecular formula = C 6 H 6 Determining Molecular Formulas

In an unknown compound you find 4.04 g of N and g O. Empirical formula? This unknown compound has a molar mass of g/mol. What is the molecular formula? Empirical formula = N 2 O 5 Empirical mass = g/mol Molecular formula = N 2 O 5

What result do you expect from a match test if …. hydrogen is present? carbon dioxide is present? Day

67.2 L of CH 4 gas = ___ grams 44.8 mg of solid Carbon = ___ L

Prelab # 5: According to the reaction in # 1, for every ___ pieces of cupric chloride ___ pieces of copper are produced. As a result we should expect to produce ___ of a mole of cpper in the first reaction, which would be ___ grams of Cu. SHOW YOUR WORK!

A sample of a compound contains g of C, g of H, and g of O. If the molar mass is g/mol what is the molecular formula. Empirical formula Molecular Formula Question of the Day Day

A sample of a compound contains 6.0 g of C and 16 g of O. The total sample is 22 g. The molecular molar mass is 44 grams Percentage Composition Empirical formula Molecular formula Determining Molecular Formulas Day

56,000 mL of O 2 gas = how many molecules of O 2 ? How many atoms of O?

- 2 molar mass convs. - 2 Av.’s # convs. - 2 Av.’s law convs. - 2 multi-step convs. - 1 percentage comp. - 1 empirical formula - 1 molecular formula - 2 content ?s (no math) 13 questions

Review section 10.3 (if needed) and complete #s for # 49 the %s can be treated as grams and used to find moles… Assignment due Tuesday 10-11

Book #s = NOW Create-a-Test = momentarily Presentations = Wednesday Chapter Quiz = Wednesday 10-12

Calculate the mass of Cu produced? Mass of beaker and Cu – mass of beaker

Calculating percent yield Percent yield – a way to compare how much you “should” get to how much you actually got Percent Yield = Actual yield Theoretic yield X 100

Desk clear and mentally prepare for Quest. Quest Group Quest Presentations

Day kL of CO gas contains how many grams? How many atoms? 140 grams CO 6e24 atoms

Review (if needed) pages AND complete #s 33, 34, 35, and 36 on pages 326 and 327. Day

Homework # 2 = now Postlabs = Friday 10-7 (tomorrow) Presentations = Wednesday Chapter Quiz = Wednesday Day

1. A mole is a _________, plus it relates to ______. 2. Molar mass of Be(NO 3 ) grams of Be(NO 3 ) 2 = ___ moles 4. = ___ molecules?