One hundred milliliters of 0200 M ATP is mixed with an ATPas

One hundred milliliters of 0.200 M ATP is mixed with an ATPase in a Dewar at 298 K, 1 atm, pH 7.0, pMg 3.0, and 0.25 M ionic strength. The temperature of the solution increases 1.48 K. What is Delta H degree for the hydrolysis of ATP to adenosine 5\'-diphosphate (ADP) and phosphate (P_i)?

Solution

First need to calculate the H and is a product of heat capacity (Cp) and temperature change (T)

H=418x1.48=618.64 J/K

Now estimate the number of moles of ATP mixed with ATPase

You have taken One hundred milliliters of 0.200 M ATP, so moles= (100mlx1L/1000ml)x0.2 mol/L=0.02 mol

What is H for the hydrolysis of ATP to ADP and phosphate= H/mol=618.64 J/K/0.02 mol=30,932 Joules/mol or 30.932 kJ/mol