Question

Carbon dioxide gas and liquid water form solid glucose (C6H12O6) and oxygen gas during photosynthesis. Chlorophyll absorbs light in the 600-700 nm region.

a) Write a balanced thermochemical equation for the formation of 1.00 mol of glucose.
... I know that it goes like this: 6CO2(g)+6H2O(l)-->C6H12O6(s)+6O2(g)... this is already balanced but not yet considered a "thermochemical equation"

b) What is the minimum number of photons with Y=680 nm needed to form 1.00 mol of glucose?

Answer 1

I think the delta Ho formation for glucose is about 3000 kJ/mol glucose but you need to look it up. I don't have all of these dH values memorized. Then
6CO2 + 6H2O + light energy --> C6H12O6 + 6O2 delta H = +3000 kJ/mol

For wavelength = 680 nm, convert to E with
E = h*c/wavelength which gives you J/photon. and convert that to photons needed for approx 3000 kJ/mol glucose.