Quiz Unit 3 Chem 211 WEB 1/30/98 (35 Points)

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Note: "Download" this quiz and return to the "Quiz Box"located outside my office. The quiz is due Monday or Tuesday, 2/2 or 2/3, when you come to campus.

1. (20 ) Silicon which is used in the manufacture of transistors, canbe produced from the reaction of gaseous silicon tetrachloride, SiCl4,with magnesium metal.

SiCl4 (g) + 2 Mg (s) = 2 MgCl2 (s) + Si (s)

a) How many moles of magnesium are required to react completelywith 100 grams of SiCl4 ?

b) How many grams of magnesium are required to react completelywith 100 grams of SiCl4 ?

c) What would be the theoretical yield of silicon, Si (s) , based onthe complete reaction of 100 grams of silicon tetrachloride ?

d) If actual yield of silicon form the "complete reaction of 100grams of SiCl4 (g), was determined to be 12.50 grams, what was the percentyield of the reaction ?

2. (15 ) Pure iron, Fe (s), can be produced in the environment of a blastfurnace form the reaction of the iron ore,hematite ( Fe2O3), with coke,C ( s),

2 Fe2O3 (s) + 3 C (s) = 3 CO2 (g) + 4 Fe (s)

a) Is this and example of an oxidation-reduction equation? If so, whichelement is oxidized, and which one is reduced ?

b) If a reaction mixture contains 500 grams of hematite and 50 gramsof "coke" , which one is the limiting reactant?

c) What is the theoretical yield of iron, Fe , from the reaction mixturein part (b) ?

d) If you wanted to calculate a percent yield for the reaction, whatadditional information do you need to know ?