can you help me with word problem?

Question

i cant solve this word problem please help me,thanks.

Ethane gas, C2H6, burns in air (i.e., reacts with the oxygen in air) to form carbon dioxide and water:
2C2H6 + 7O2----> 4CO2 + 6H2O

a) How many moles of O2 are needed for the complete combustion of 20.7 mol of ethane?

b) How many grams of CO2 are produced for each 6.66 g of H2O produced?

Answer 1

a) From your balanced equation, 2 moles of ethane needs 7 moles of oxygen gas to complete combustion. Since you are given with 20.7 mol ethane, the number moles O2 needed is

moles O2 = 7*20.7 / 2 = 72.45 moles

b) For each 6.66g H2O, there are 6.66g/18.0g/mol or 0.37 moles H2O. Since 6 moles of H2O is produced for every 4 moles of CO2 produced, actual moles CO2 produced is 4*0.37/6 or 0.2467 moles CO2. The mass of CO2 then is

mass CO2 = 0.2467mol * 44.01g/mol
mass CO2 = 10.86g

Answer 2

a) ratio of ethane to oxygen = 2:7
Hence moles of O2 needed would be = 20.7 x 7/2
= 72.45 mols

b) moles of H20 produced = 6.66/18
= 0.37 mols
ratio of H2O to CO2 = 6:4
Thus moles of CO2 produced would be = 0.37 x 4 /6
=0.2467 moles
grams of CO2 = 0.2467 x 44
=10.85g

Answer 3

for question a , u must know the formula to find the moles . it is n=mv/1000. then find the relative atomic mass for ethane , C2H6 . when you find the RAM , divide it with the number of mole of ethane which is 20.7 mol . then , you can get the no. of 1 mole of ethane. the number of mole of ethane is equal to 1 mole of oxygen gas,O2 . then find the RAM for 7 oxygen gas . After that , multiply it with the no. of mole for 1 mole of oxygen gas .
for qustion b) , get the no. of 1 mole of water which is same as 1 mole of carbon dioxide gas . then , multiply it with 7 atom .

Answer 4

2 moles of ethane need 7 moles of Oxygen. So, 20.7 moles of ethane need 7 x 13.35 = 93.45 moles of Oxygen.

Off hand I can't answer your other question. You need to convert moles in grams and do the calculations.