if the heat of combustion of glucose is -2808 kJ/mol, how many grams of glucose are required to supply 1650 kJ of heat?
2808 kJ/mol = 2808 kJ/180g.
So (2808 kJ/180g) x ?g = 1650 kJ.
Solve for ?g.
To determine the number of grams of glucose required to supply a certain amount of heat, you need to use the equation:
q = n * ΔH
where:
q is the amount of heat in joules (J),
n is the number of moles of glucose, and
ΔH is the heat of combustion of glucose in joules per mole (J/mol).
First, we need to convert the heat of combustion from kJ to J:
ΔH = -2808 kJ/mol = -2808 * 1000 J/mol = -2,808,000 J/mol
Now, we rearrange the equation to solve for moles (n):
n = q / ΔH
Given q = 1650 kJ = 1650 * 1000 J, we have:
n = (1650 * 1000 J) / (-2,808,000 J/mol)
n ≈ -0.588 mol
Note: The negative sign indicates that the reaction is exothermic, meaning it releases energy.
Finally, we can convert moles of glucose to grams using the molar mass of glucose, which is approximately 180 g/mol:
mass = n * molar mass
mass = -0.588 mol * 180 g/mol
mass ≈ -106 g
The negative sign indicates that we need to supply 106 grams of glucose to release 1650 kJ of heat.