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1) The combustion of ethanol prodces carbon dioxide and water. After 4.62 mL of

ID: 792224 • Letter: 1

Question

1) The combustion of ethanol prodces carbon dioxide and water. After 4.62 mL of ethanol (0.789g/mL) was allowed to burn in the presence of 15.55g of oxygen gas, 3.72mL of water (1.00g/mL) was collected. what is the percent yield of the reaction?(please show all the process of your work)!! I got this Blanced equation +3O2---> 2CO2+3H2O but have no idea what is the next step..I might wrong for the balancing too.. however ethanol is CH3CH2OH.



2) Suppose you have a 5.00M calcium choloride solution. You have a 100.0mL pipette, and 3 volumetric flasks (100,250 and 500mL). Using the pipette and one of the columetric flasks, please explain how to make a solution that is 4.00M in choloride ions.

(You can choose one of 100, 250 and 500mL for this problem.) show all of your work!!

Explanation / Answer

1)


bal. rxn.: C2H5OH + 3 O2 -----> 2CO2 + 3 H2O

moles reactants-
C2H5OH: g=density x vol, g= 4.62ml x 0.789 g/ml= 3.65 g C2H5OH
3.65 g/46 g/mole=0.079 moles ethanol
O2: 15.45 g/16 g/mole=0.966 moles

from bal. rxn., 3 moles of O2 required per mole of C2H5OH
1/3 x .966 moles of O2= 0.322 moles of ethanol required, since there are only 0.079 moles, ethanol is limiting reactant.

from bal. rxn., 1 mole ethanol reacts to form 3 moles water
theo. yield: 0.079 moles x 3 x 18 g/mole H2O= 4.27 g H2O
% yield= actual/theo. x100
% yield=3.71 g/4.27 x100
% yield= 86.9