Quiz 9 practice answers             Chemistry 20            Name__________________
Significant figures count. Show all work and steps for credit.
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1      Calculate the number of grams of hydrogen in 30.0 g of glucose (C6H12O6).
30.0g C6H12O6 x 1mole C6H12O6 /180 g C6H12O6  x 12 mole H/1 mol C6H12O6  x 1.008 g H/mole H=
2      How many moles of H2O are produced when 4.5 moles of C2H6 are burned in oxygen?
2C2H6 + 7O2 ---> 6H2O + 4CO2
4.5 mole C2H6 x 6mole H2O/2 mol C2H6 =
3      6.00 g of H2SO4 is reacted with 5.00 g of Mg(HCO3)2 . Calculate the amount of each reactant and product after the reaction is complete.
H2SO4 + Mg(HCO3)2 ---> MgSO4 + 2CO2 + 2H2O

6.00g H2SO4 x 1 mol H2SO4 /98.06 g H2SO4 =  .0612 mol H2SO4
5.00g Mg(HCO3)2 x 1 mol Mg(HCO3)2 / 146.341g Mg(HCO3)2 =0.0342 mol Mg(HCO3)2
Therefore Mg(HCO3)2 is limiting.
5.00g Mg(HCO3)2 x 1mol Mg(HCO3)2 / 146.34 g Mg(HCO3)2 x 1mol H2SO4 /1mol Mg(HCO3)2= moles of H2SO4 used which needs to be subtracted from 0612 mol H2SO4 .
5.00g Mg(HCO3)2 x 1mol Mg(HCO3)2 / 146.34 g Mg(HCO3)2 x 1mol MgSO4 /1mol Mg(HCO3)2= moles of MgSO4 formed.
5.00g Mg(HCO3)2 x 1mol Mg(HCO3)2 / 146.34 g Mg(HCO3)2 x 2mol CO2  /1mol Mg(HCO3)2= moles of CO2 formed.
5.00g Mg(HCO3)2 x 1mol Mg(HCO3)2 / 146.34 g Mg(HCO3)2 x 2mol H2O  /1mol Mg(HCO3)2= moles of H2O formed.
4      20.0 g of chlorine reacts with 15.0 g of ethane (C2H6) to form 1,2-dichloroethane (C2H4Cl2) and HCl. The yield is 22.0%. How many grams of 1,2-dichloroethane are produced?
Cl2 + C2H6 ---> C2H4Cl2 + 2HCl

20.0 g Cl2 x 1mole Cl2/70.9 g Cl2 x 1 mol  C2H4Cl2/ 1mol Cl2 x 98.95 g/molC2H4Cl2 x .22 = g C2H4Cl2.