What mass of carbon dioxide is consumed by the reaction of 3.8g of water?

Question

Green plants use light from the Sun to drive photosynthesis. Photosynthesis is a chemical reaction in which water H2O

 and carbon dioxide CO2

 chemically react to form the simple sugar glucose C6H12O6

 and oxygen gas O2

.

What mass of carbon dioxide is consumed by the reaction of 

3.8g

 of water?Be sure your answer has the correct number of significant digits.

Answer 1

Here is the balanced equation for photosynthesis:

6CO2 + 6H2O ==> C6H12O6 + 6O2

Using dimensional analysis and stoichiometry, we calculate mass of CO2 as follows:

3.8 g H2O x 1 mol H2O/18 g x 6 mol CO2 / 6 mol H2O x 44 g CO2/mol CO2 = 9.3 g CO2 consumed (2 s.f.)