# In photosynthesis glucose c6h12o6 and o2 are produced from co2 and h2o. 6CO2(g)+6H2O(l)+680kcal=C6H12O6(aq)+6O2(g) How much heat in kilojoules is needed to produce 19.5g of c6h12o6?

## Not sure how to set up the conversion for the problem ##### 1 Answer
Jul 28, 2016

You need 308 kJ of heat energy.

#### Explanation:

The thermochemical equation is

${\text{6CO"_2 + "6H"_2"O" + "680 kcal" → "C"_6"H"_12"O"_6 + "6O}}_{2}$

The steps in your calculation will be:

1. Convert grams of glucose to moles of glucose.
2. Convert moles of glucose to kilocalories.
3. Convert kilocalories to kilojoules.

1. Calculate moles of glucose

$\text{Moles of glucose" = 19.5 color(red)(cancel(color(black)("g glucose"))) × "1 mol glucose"/(180.16 color(red)(cancel(color(black)("g glucose")))) = "0.1082 mol glucose}$

2. Calculate kilocalories

$\text{Kilocalories" = 0.1082 color(red)(cancel(color(black)("mol glucose"))) × "680 kcal"/(1 color(red)(cancel(color(black)("mol glucose")))) = "73.60 kcal}$

3. Convert kilocalories to kilojoules

$\text{Kilojoules" = 73.60 color(red)(cancel(color(black)("kcal"))) × "4.184 kJ"/(1 color(red)(cancel(color(black)("kcal")))) = "308 kJ}$