Quantities in Chemical Reactions

the “amounts” of any reactant or product in a chemical reaction are related to each other Law of Conservation of Mass balancing equations by balancing atoms the study of the numerical relationship between chemical quantities in a chemical reaction is called reaction stoichiometrystoichiometry

Making Pancakes “right recipe” (or stoichiometric amounts) the # of pancakes you can make depends on the amount of the ingredients/“reactants” you use this relationship can be expressed mathematically 1 cup flour : 2 eggs : ½ tsp baking powder  5 pancakes reactant #1 reactant# 2 reactant #3 “product” 1 cup flour + 2 eggs + ½ tsp baking powder  5 pancakes

Making Pancakes if you want to make more/less than 5 pancakes you can use the number of eggs you have to determine the number of pancakes you can make Assuming you have enough flour and baking powder eg. If you have 8 eggs you can make 20 pancakes

Mole-to-Mole ConversionsMole-to-Mole Conversions “n to n” the balanced equation is the “recipe” for a reaction the equation 3 H 2(g) + N 2(g)  2 NH 3(g) tells us that 3 molecules of H 2 react with exactly 1 molecule of N 2 and make exactly 2 molecules of NH 3 or 3 molecules H 2 : 1 molecule N 2  2 molecules NH 3 Note the equation coefficients are also your MOLE ratios 3 moles H 2 : 1 mole N 2  2 moles NH 3

Practice Problem #1 “n to n” Mole-to-Mole Conversions How many moles of NaCl result from the reaction of 3.4 mol of Cl 2 with 6.8 mol of Na? (i.e. theoretical yield) 2 Na (s) + Cl 2 (g)  2 NaCl (s) a)Determine the “ N p ” ratio b)Determine the “n” ratio c)Determine the “required to find” information for the given “n” ratio, include metric units and express to the appropriate # of significant digits ANSWER mol NaCl