Consider the combustion of ethane:

Question

2C2H6(g)+7O2(g)-->4CO2(g)+6H2O(g)
If the ethane is burning at the rate of 0.7 mol/L × s, at what rates are and being produced?

Answer 1

at what rates ???? are being produced..

the mole ratios are handy

well, you get twice as much CO2 as ethane, mole wise. Now at the same temp, pressure, this means twice as much volume also

so, lets just consider the moles first.
ethane is being consumed at .7mol/sec, which means CO2 is being produced at 1.4 moles per sec, and water is being produced at 2.1 moles/second.

Now consider volume. All are gases, at the same temp pressure, moles occupy the same volume, so volume wise..
for each liter of ethane, we get two liters of CO2, and three liters of H2O.

so in the rate you specified, in moles per liter per second...
if ethane is being consumed at .7 mol/liter.sec, then CO2 is being produced at the rate of 1.4moles/2 liters (or .7 moles/liter), and likewise, water is being produced at .7mol/liter.sec

I am not certain your instructor intended to ask for this result.

Answer 2

yes that's what he was asking, thank you!