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 water is consumed by the reaction of 7.3 g of carbon dioxide?

Answer 1

Answer:

Mass of H₂O is 3.0g

Explanation:

The reaction equation is given as:

        6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Parameters that are known:

Mass of CO₂ used = 7.3g

Unknown: mass of water consumed = ?

Solution

To solve this kind of problem, we simply apply some mole concept relationships.

• First, we work from the known to the unknown. From the problem, we have 7.3g of CO₂ that was used. We can find the number of moles from this value using the expression below:

        Number of moles of CO₂ =  $\frac{mass}{molar mass}$

• From this number of moles of CO₂, we can use the balanced equation to relate the number of moles of CO₂ to that of H₂O:

       6 moles of CO₂ reacted with 6 moles of H₂O(1:1)

• We can then use the mole relationship with mass to find the unknown.

Workings

>>>>     Number of moles of CO₂ =?

          Molar mass of CO₂ :

              Atomic mass of C = 12g

               Atomic mass of O = 16g

        Molar mass of CO₂ = 12 + (2 x16) = 44gmol⁻¹

     Number of moles of CO₂ = $\frac{7.3}{44}$ = 0.166moles

>>>>>>   if 6 moles of CO₂ reacted with 6 moles of H₂O, then 0.166moles of CO₂ would produce 0.166moles of H₂O

>>>>>> Mass of water consumed = number of mole of H₂O x molar mass

             Mass of H₂0 = 0.166 x ?

Molar mass of H₂O:

                 Atomic mass of H = 1g

                 Atomic mass of O = 16

 Molar mass of H₂O = (2x1) + 16 = 18gmol⁻¹

Mass of H₂O = 0.166 x 18 = 3.0g