How many moles of sugar are required to react completely with 3.26 mol of oxygen?
Write the equation and balance it, then follow the instructions on the link I'm giving you. I'll help by giving you the balanced equation.
C12H22O11 + 12O2 ==>12CO2 + 11H2O
http://www.jiskha.com/science/chemistry/stoichiometry.html
This link will work any stoichiometry problem you have.
_____C2H5OH +_____ O2 „_ _____CO2 + _____H2O
Convert 3.09 g PCl5 to molecules
Find the percent by mass of oxygen in CaCO3
You should post separate questions for these, otherwise they sometimes get left behind.
C2H5OH + 3O2 ==> 2CO2 + 3H2O
%oxygen = (mass Oxygen/molar mass CaCO3)*100 = ?
mass oxygen, use atomic mass O or 3*16 = ?
moles PCl5 = grams/molar mass.
Then remember there are 6.022E23 molecules in one (1) mole of anything.