# limiting & excess

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Limiting & Excess. Cookie Stoichiometry. How many batches could you make with 4 eggs 6 cups of flour 2/3 cups of butter. To make one batch, it requires: 2 eggs 2 cups of flour 2/3 cups of butter. The cups of butter was your limiting reagent - PowerPoint PPT Presentation

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Limiting & Excess

Limiting & ExcessCookie StoichiometryTo make one batch, it requires:2 eggs2 cups of flour2/3 cups of butterHow many batches could you make with4 eggs6 cups of flour2/3 cups of butterThe cups of butter was your limiting reagentThe eggs and flour were your excess reagentsBut how could you show this mathematically?

2 Together. 3 on your Own!Whiteboard!

Example 120.00 g of H2 react with 100.0 g of O2 according to the reaction2 H2 + O2 2 H2OWhich reactant is limiting and which reactant is in excess?Example 11. Calculate the number of moles of a product formed.Mole of H2O (based on H2)=20.00 g H2x1 mol H2x2 mol H2O=10.0 mole H2O2.0 g H22 mol H2Mole of H2O (based on O2)=100.0 g O2x1 mol O2x2 mol H2O=6.25 mol H2O32.0 g O21 mol O2Example 1Determine the limiting and excess reactants.O2 is the limiting reactant.H2 is the excess reactant.2. How much H2 (in grams) is left after O2 runs out?Example 13. To find mass of H2 in excess, find the mass of H2 which will react based on the mass of the limiting reactant.Mass of H2 (based on O2)=100.0 g O2x1 mol O2x2 mol H2x2.0 g H2=12.5 g H232.0 g O21 mol O21 mol H2Example 14. Then, subtract the mass of H2 which reacts from the starting mass of H2.

Mass of H2 (in excess) = mass H2 (at start) mass H2 (reacted) = 20.00 g 12.5g = 7.5 g

Take Attendance Example 2If 56.8 g of FeCl2, 14.9 g of KNO3 and 40.0 g of HCl are mixed according to the reaction

FeCl2 + KNO3 + HCl FeCl3 + NO + H2O + KCl

What is the limiting reactant?

How many grams of each excess reactant left in the reaction vessel? Example 2If 56.8 g of FeCl2, 14.9 g of KNO3 and 40.0 g of HCl are mixed according to the reaction

3 FeCl2 + KNO3 + 4 HCl 3 FeCl3 + NO + 2 H2O + KCl

What is the limiting reactant?

How many grams of each excess reactant left in the reaction vessel?

Example 2If 56.8 g of FeCl2, 14.9 g of KNO3 and 40.0 g of HCl are mixed according to the reaction

3 FeCl2 + KNO3 + 4 HCl 3 FeCl3 + NO + 2 H2O + KCl

What is the limiting reactant? KNO3

How many grams of each excess reactant left in the reaction vessel? Example 2If 56.8 g of FeCl2, 14.9 g of KNO3 and 40.0 g of HCl are mixed according to the reaction

3 FeCl2 + KNO3 + 4 HCl 3 FeCl3 + NO + 2 H2O + KCl

What is the limiting reactant? KNO3

b) How many grams of each excess reactant are actually present in excess? FeCl2 = 0.8g, HCl = 18.5g

Example 3If 3.2 g of CuSO4, 2.5 g of water and 3.0 g of SO2 are reacted together in the reaction:CuSO4 + H2O + SO2 Cu + H2SO4Which reactant is the limiting reactant?What is the mass of each of the excess reactants?

Example 4700. mL of 0.350 M ammonia (NH3) solution is mixed with 15.0 g of solid magnesium to produce magnesium nitride and hydrogen gas.Which reactant is in excess?How much (in grams) of the excess reactant remains after the reaction is complete?

Example 5:For the reaction:TiO2(aq) + B4C(g) + C(s) TiB2(aq) + CO(g)If 11.5 L of 0.800 M TiO2, 455 g of solid carbon and 184 L of B4C gas at STP react together. Find the amount (based on the original units given) of the reactants left over.Example 5:For the reaction:2TiO2(aq) + B4C(g) + 3 C(s) 2TiB2(aq) + 4CO(g)If 11.5 L of 0.800 M TiO2, 455 g of solid carbon and 184 L of B4C gas at STP react together. Find the amount (based on the original units given) of the reactants left over.