A hemoglobin molecule (molar mass =65000 g) can bind up to 4 oxygen molecules. In a certain experiment a .085-L solutoin containing 6.0 g of deoxyhemoglobin was reacted with excess of oxygen in a constant-pressure calorimeter of negligible heat capacity. calculate the enthalpy of the reaction per mole of oxygen bound if the temperature rose by .044 degree celcius. (specific heat of solution is equal to that of water)

Question

A hemoglobin molecule (molar mass =65000 g) can bind up to 4 oxygen molecules. In a certain experiment a .085-L solutoin containing 6.0 g of deoxyhemoglobin was reacted with excess of oxygen in a constant-pressure calorimeter of negligible heat capacity. calculate the enthalpy of the reaction per mole of oxygen bound if the temperature rose by .044 degree celcius. (specific heat of solution is equal to that of water)

Answer 1

To calculate the enthalpy of the reaction per mole of oxygen bound, we first need to determine the energy change (ΔE) in the system. We can then use the equation ΔE = q + w, where q is the heat absorbed or released and w is the work done.

Given:
- Molar mass of hemoglobin (Hb) = 65000 g/mol
- No. of oxygen molecules bound per Hb = 4
- Volume of solution (V) = 0.085 L
- Mass of deoxyhemoglobin = 6.0 g
- Temperature change (ΔT) = 0.044 °C

First, we need to determine the number of moles of deoxyhemoglobin in the solution:
moles of deoxyhemoglobin = mass of deoxyhemoglobin / molar mass of deoxyhemoglobin
moles of deoxyhemoglobin = 6.0 g / (65000 g/mol)

Next, we determine the number of moles of oxygen bound by dividing the moles of deoxyhemoglobin by 4 (since each Hb molecule can bind up to 4 oxygen molecules).

moles of oxygen bound = moles of deoxyhemoglobin / 4

Now, we can calculate the heat absorbed or released (q) using the specific heat capacity of water and the equation q = m * C * ΔT, where m is the mass of the solution and C is the specific heat capacity.

The mass of the solution can be calculated using the density (ρ) and the equation m = V * ρ.
Assuming the density of water, ρ = 1 g/mL = 1000 g/L, we have:
mass of solution = volume of solution * density of water

Finally, we calculate the enthalpy of the reaction per mole of oxygen bound by dividing the calculated heat absorbed or released by the moles of oxygen bound:

Enthalpy change per mole of oxygen bound = q / moles of oxygen bound

Now you can substitute the given values into the equations and calculate the enthalpy change per mole of oxygen bound.