There is a beaker containing 100mL of 1.000 M HCl poured into a calorimeter and then a second beaker containing 100mL of 1.000 M NaOH poured into the calorimeter. The initial temperature is of 25.01 Celcius and a final of 31.04. Is answer number five correct?
1) Is the reaction endothermic or exothermic? What will be the sign of ^Hrxn(enthalpy) ?
2) Calculate the mass of the reaction mixture that was in the calorimeter?(To do this, first determine the total volume of the solution based on the assumption that the volumes are additive and that the density of the solution is the same as that of pure water, 1.0 g/mL.)
3) Calculate the total heat released in the reaction, assuming that the specific heat capacity of the solution is the same as that of pure water, 4.184 J/K g. (heat of reaction = m x C x ^T)
4) Calculate the number of moles of NaOH used in the reaction by multiplying the volume of NaOH times the molarity(1.000 mol/L)
5) Calculate ^Hrxn, in kJ/mol, of NaOH for the reaction?
1) a) exothermic
b) enthalpy
2) 100ml + 100ml = 200ml x 1.0g/ml = 200 grams
3) heat = mass x specific heat x delta temperature
= 200 ( 4.184) (T1 - T2) = 836.8 (25.01 - 31.04) = 836.8(- 6.03) = - 5046 joules
4) 100ml NaOH x 1 molar (1mole per liter = 1 mole per 1000ml) = 0.1 moles (in 100ml)
5) Heat of reaction = heat of formation of the products - heat of formation of the reactants
= [- 425.93 + (- 92.30)] - [(- 181.42) + (-241.83)]
= - 518.23 - [- 423.25] = 1518.23 + 423.25 = - 94.98 kj / mole