Question

Green plants use light from the Sun to drive photosynthesis, a chemical reaction in which liquid water and carbon dioxide gas form aqueous glucose C6H12O6 and oxygen O2 gas. Calculate the moles of water needed to produce 0.500mol of glucose. Be sure your answer has a unit symbol, if necessary, and round it to 3 significant digits.

Answer 1

In order to find the answer we need to set the equation up first, so the reaction for photosynthesis is:

6 CO2 + 6 H2O + energy -> C6H12O6 + 6 O2

Now by checking the molar ratio between water and glucose we see that for every 6 moles of H2O we will end up having 1 mol of C6H12O6, so we have a 6:1 molar ratio, now in order to produce 0.500 we will find out by doing the following calculation:

6 H2O = 1 C6H12O6

x H2O = 0.500 C6H12O6

x = 3.00 moles of H2O are needed to produce 0.500 moles of glucose