(Mole-Mole problems)

(Mole-Mole problems) Use the coefficients to predict the amount of reactant consumed or product formed The ratio of the coefficients is a ratio of the moles taking part in a reaction. Reactants (on the left of the arrow) are consumed Products (on the right of the arrow) are formed Given the number of moles of any substance in a reaction, you can use the coefficients to find the number of moles of any other substance. J Deutsch 2003

Place the moles given over the coefficient for that substance and set up a proportion with the coefficients. How many moles of oxygen are produced when 4 moles of KClO3 react according to the equation: 2 KClO3 2 KCl + 3 O2 4 X 2 KClO3 2 KCl + 3 O2 4 = X 2 3 cross multiply to get 2X = 12 X=6 moles unknown given J Deutsch 203

Regents Question: 06/03 #20 þ Given the reaction: PbCl2 (aq) + Na2CrO4 (aq) PbCrO4 (s) + 2NaCl(aq) What is the total number of moles of NaCl formed when 2 moles of Na2CrO4 react completely? (1) 1 mole (2) 2 moles (3) 3 moles (4) 4 moles þ J Deutsch 2003

Regents Question: 06/03 #20 þ Given the reaction: PbCl2 (aq) + Na2CrO4 (aq) PbCrO4 (s) + 2NaCl(aq) What is the total number of moles of NaCl formed when 2 moles of Na2CrO4 react completely? (1) 1 mole (2) 2 moles (3) 3 moles (4) 4 moles þ J Deutsch 2003

Regents Question: 06/02 #34 A compound has a gram formula mass of 56 grams per mole. What is the molecular formula for this compound? CH2 C2H4 C3H6 C4H8 þ J Deutsch 2003

Regents Question: 01/03 #42 þ Given the equation: 2C2H2(g) + 5O2(g) 4 CO2(g) + 2H2O(g) How many moles of oxygen are required to react completely with 1.0 mole of C2H2? 2.5 2.0 5.0 10 þ J Deutsch 2003