Choose Your Category The MoleAverage Atomic Mass and Molar Mass FormulasPercentage Composition Limiting Reactants Percentage Yield and Error Vocab The Final Question

The Mole The SI base unit used to measure the amount of a substance whose number of particles equals the number of atoms of carbon in exactly 12 grams of carbon-12 Back The Answer is the mole

The Mole The number of atoms in a mole of any pure substance is called Back The Answer is the Avogadro's number

The Mole What can be said about the atoms in 1 mol Ag and 1 mol Au? Back The Answer is they contain the same number of atoms.

The Mole The _______________ in a chemical equation represent the relative number of moles of reactants and products. Back The Answer is coefficients.

The Mole In the reaction N 2 + 3H 2  2NH 3, what is the mole ratio of nitrogen to ammonia? Back The Answer is 1 to 2

Average Atomic Mass and Molar Mass Using a periodic table, what is the average atomic mass of zinc? Back The Answer is 65.4 amu.

Average Atomic Mass and Molar Mass What is 120 g/mol in amu? Back The Answer is 120 amu.

Average Atomic Mass and Molar Mass The atomic mass of hydrogen is amu. This is because there is more than one ____________ of hydrogen. Back The Answer is isotope.

Random Points 600 points

Average Atomic Mass and Molar Mass Calculate the molar mass of barium nitrate, Ba(NO 3 ) 2. Back The Answer is g/mol.

Average Atomic Mass and Molar Mass Change 58 grams of water into moles. Back The Answer is 3.22 moles. (58g x 1mol/18 g)

Formulas A formula that shows the simplest whole- number ratio of the atoms in a compound is the ________________ ___________. Back The Answer is empirical formula.

Formulas The first step in finding the empirical formula from the percentage composition is to assume that you have this many grams? Back The Answer is 100 g.

Formulas A compound’s empirical formula is NO 2. If the formula mass is 92 amu, what is the molecular formula? Back The Answer is N 2 O 4

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Formulas A compound contain 79.85% carbon and % hydrogen. What is the empirical formula? Back The Answer is CH 3

Formulas A compound contains 9.1 % hydrogen, 54.5 % carbon and 36.4 % oxygen. What is the molecular formula if its molar mass is132 amu? Back The Answer is H 12 C 6 O 3

Percentage Composition – 100 The percentage of sulfur in SO 2 is about 50%. What is the percentage of oxygen in this compound? Back The Answer is 50%.

Percentage Composition – 200 Calculate the percentage of sulfur in CuSO 4. Back The Answer is 20.09%.

Random Points 300 points

Percentage Composition – 300 What is the percentage composition of each element in CuCl 2 ? Back The Answer is 47.3% Cu, 52.7% Cl.

Percentage Composition – 400 What is the percentage composition of CF 4 ? Back The Answer is 13.6% C, 86.4% F

Daily Double

Percentage Composition – 500 What is the percentage composition of each element in (NH 4 ) 2 HPO 4 ? Back The Answer is 21.2% N, 6.8 % H, 23.5% P, and 48.5% O

Limiting Reactants To determine the limiting reactant in a chemical reaction, one must change each reactant into the ________ product with the ________ units. Back The Answer is same (and same).

Limiting Reactants A chemical reaction involving substances A and B stops when B is completely used. B is the ___________________. Back The Answer is limiting reactant

Limiting Reactants All the other reactants besides the limiting reactant are called ____________ reactants Back The Answer is excess.

Limiting Reactants The first step in most stoichiometry problems is to _____________. Back The Answer is convert given quantities to moles.

Random Points 800 points

Limiting Reactants If 2 moles of each reactant are available for the reaction described by the following equation, SiO 2 (s) + 3C(s)  SiC(s) + 2CO(g), determine which substance is the limiting reactant by calculating the moles of SiC each of the reactants can produced. Back The Answer is carbon.

Percentage Yield and Error Back The Answer is percentage yield What is the ratio of the actual yield to the theoretical yield, multiplied by 100%?

Percentage Yield and Error Actual yield must be determined by __________________. Back The Answer is experiments.

Random Points 400 points

Percentage Yield and Error For the reaction CH 4 (g) + 2O 2 (g)  CO 2 (g) + 2H 2 O(g), calculate the percentage yield of carbon dioxide if 1000 g of methane (needed to calculate theoretical) react with excess oxygen to produce 2300 g of carbon dioxide (experimental). Back The Answer is 83.9%.

Percentage Yield and Error What is the percent of error in evaluating the molecular mass of a compound if the experimental value was 69.2 amu and the known value was 75.5 amu? Back The Answer is 8.3%

Random Points 400 points

Percentage Yield and Error For the reaction CH 4 (g) + 2O 2 (g)  CO 2 (g) + 2H 2 O(g), calculate the percentage error of carbon dioxide if 1000 g of methane (needed to calculate theoretical) react with excess oxygen to produce 2300 g of carbon dioxide (experimental). Back The Answer is 16.1%

Vocab The proportional relationship between two or more substances during a chemical reaction Back The Answer is stoichiometry

Vocab The mass in grams of 1 mol of a substance Back The Answer is the molar mass

Vocab The percentage by mass of each element in a compound Back The Answer is the percentage composition

Vocab The measured amount of a product of a reaction Back The Answer is actual yield

Vocab A chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of the atoms Back The Answer is the molecular formula

The Final Question The final question has to deal with: »Stoichiometry Make your wager and hand it to the teacher

Stoichiometry How many molecules of hydrogen are produced if 20.0 g of sodium metal react with excess water according to the chemical equation: 2 Na(s) + 2 H 2 O(l)  2 NaOH(aq) + H 2 (g)?

And the Answer is: The Answer is 2.62 x x (1 mol/23 g) = 0.87 mol Na x (1 mol H 2 /2 mol Na) = mol H 2 x (6.02x10 23 molecules/1 mol) =