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1)For the following reaction, 17.4 grams of carbon dioxide are allowed to react

ID: 1016416 • Letter: 1

Question

1)For the following reaction, 17.4 grams of carbon dioxide are allowed to react with 49.2 grams of potassium hydroxide . carbon dioxide(g) + potassium hydroxide(aq) potassium carbonate(aq) + water(l)

-What is the maximum amount of potassium carbonate that can be formed? ____grams

-What is the FORMULA for the limiting reagent?

-What amount of the excess reagent remains after the reaction is complete? ______grams

2)

For the following reaction, 4.35 grams of diphosphorus pentoxide are mixed with excess water . The reaction yields 4.73 grams of phosphoric acid .

What is the theoretical yield of phosphoric acid ? grams What is the percent yield for this reaction ? %

Explanation / Answer

2KOH + CO2 -------> K2CO3 + H2O

no of moles of Co2 = W/G.M.Wt   = 17.4/44   = 0.395 moles

no of moles of KOH   = W/G.M.Wt = 49.2/56 = 0.878moles

1 mole of Co2 react with 2 moles of KOH

0.395 moles of CO2 react with = 2*0.395/1 = 0.79 moles of KOH

limiting reagent is CO2

Excess reagent is KOH

1 mole of CO2 react with KOH to form 1 mole of K2CO3

0.395 moles of CO2 react with KOH to form = 0.395 moles of K2CO3

mass of K2CO3 = no of moles * gram molar mass

                         = 0.395*138 = 54.51g of K2CO3

no of moles of excess reagent left over = 0.878-0.79 = 0.088 moles of KOH

mass ofexcess reagent left over KOH = 0.088*56 = 4.928g of KOH

2. P2O5 + 3H2O ----->2H3PO4

1 mole of P2O5 react with H2O to form 2 moles of H3PO4

142 g of P2O5 react with H2O to form 2*98g of H3PO4

4.35g of P2O5 react with H2O to form = 2*98*4.35/142 = 6g of H3PO4

theoretical yield = 6g

    percentage of yield = actual yield*100/theoretical yield

                                     = 4.73*100/6   = 78.83%   >>>> answer