1) According to the following reaction, how many grams of water are required for

ID: 1016084 • Letter: 1

Question

1) According to the following reaction, how many grams of water are required for the complete reaction of 28.3 grams of silicon tetrafluoride?

silicon tetrafluoride (s) + water (l) hydrofluoric acid (aq) + silicon dioxide (s)

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

3)For the following reaction, 17.4 grams of carbon dioxide are allowed to react with 49.2 grams of potassium hydroxide .

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

What is the FORMULA for the limiting reagent?

1. SiF4 + 2H2O ----> 4HF + SiO2

1 mole of SiF4 react with 2 moles of H2O

104g of SiF4 react with 2*18g of H2O

28.3g of SiF4 react with = 2*18*28.3/104 = 9.79g of H2O

2. S + 2CO -------> So2 + 2C

no of moles of S = W/G.A.Wt = 11.6/32 = 0.3625 moles

no of moles of Co = W/G.A.Wt = 25.1/28 = 0.896 moles

1 mole of S react with 2 moles of Co

0.3625 moles of S react with = 2*0.3625/1 =0.725 moles of CO

limiting reagent is S

1 mole of S react with CO to form 1mole of So2

0.3625 moles of S react with CO to form = 0.3625 moles of So2

mass of SO2 = no of moles of SO2* gram molar mass of So2

= 0.3625*64 = 23.2g of SO2

no of moles of left over of excess reagent = 0.896-0.725 = 0.171moles of CO

mass of excess reagent = no of moles * gram molar mass of Co

= 0.171*28 = 4.788g of CO left over

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