DeltaHdegree_f[C_6H_12O_6(S)] =-1273.3 kj/mol (30%) The food we eat is broken do

Question

DeltaHdegree_f[C_6H_12O_6(S)] =-1273.3 kj/mol (30%) The food we eat is broken down, or metabolize, in stages. An interesting aspect of metabolize is that the overall change in energy is the same as it is combustion. Various foods have different energy content (fuel value), which can be characterized by the enthaloy of the complete combustion (in kcal) par gram of food. Compare the energy contents of plasmatic acid (C_16H_32O_2) (a dietary fat found in beef and butter) and table sugar (sucrose, C_12H_22O_11):

Explanation / Answer

a.

The balance combustion reaction of palmitic acid and sucrose are as follows:

C16H32O2 + 23O2 --------> 16H2O + 16CO2

C12H22O11 + 12 O2 ---------> 12 CO2 + 11 H2O

b.

Calculate the enthalpy of Combustion reaction of palmitic acid

C16H32O2 + 23O2 --------> 16H2O + 16CO2

dH = H product – H reactants

dH = (16* -285.8 KJ/mol + 16*-393.5 KJ/mol) – (-208 KJ/mol)

dH = -10660.8 KJ/mol

1.0 kcal =4.184 KJ

dH = -2547.992352 Kcal /mol

Calculate the enthalpy of Combustion reaction of sucrose

C12H22O11 + 12 O2 ---------> 12 CO2 + 11 H2O

dH = H product – H reactants

dH = (11* -285.8 KJ/mol + 12*-393.5 KJ/mol) – (-2226.1KJ/mol)

dH = -5639.7KJ/mol

1.0 kcal =4.184 KJ

dH = -1347.92065 Kcal /mol

c.

molar mass of Palmitic acid = 256.4241 g/mol

dH = -10660.8 KJ/mol

dH = -10660.8 KJ/mol/ 256.4241 g/mol

dH = -41.57 KJ/ g

dH = -2547.992352 Kcal /mol

dH = -2547.992352 Kcal /mol/ 256.4241 g/mol

dH = -9.94 kCal /g

Molar mass of sucrose =342.2965 g/mol

dH = -5639.7KJ/mol

dH = -5639.7KJ/mol /342.2965 g/mol

dH = -16.48 KJ/ g

dH = -1347.92065 Kcal /mol

dH = -1347.92065 Kcal /mol/ 342.2965 g/mol

dH = -3.94 kCal /g

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