Question

Determination of Standard Enthalpy of Solution of NaOH in Acid

Mass of NaOH and bottle (g)	8.80
Mass of bottle (g)	6.90
Mass of NaOH (g)	1.90
Mass of calorimeter and solution (g)	61.20
Mass of calorimeter (g)	9.07
Mass reaction mixture (g)	52.13

Time (min)	Temperature (°C)	Time (min)	Temperature (°C)
1	24.2	11	42.0
2	24.2	12	41.5
3	24.2	13	41.0
4	24.2	14	40.6
5	24.2	15	40.1
6	34.3	16	39.7
7	42.4
8	43.6
9	43.1
10	42.6

Determination of Standard Enthalpy of Solution of NaOH in Acid

From your graph,         T_i       = ________ °C

         T_f      = ________ °C

Hence        T    = ________ °C

         q       = – C_water m_soln T = – 4.184 x ________ x ________

                   = ________ J

n = m_NaOH/M_r = ________ /40.00 = ________ mol

H° = q/n = ________ / ________ = ________ J/mol = ________ kJ/mol

Answer 1

Determination of Standard Enthalpy of Solution of NaOH in Acid

Mass of NaOH (g)	1.90
Mass reaction mixture (g)	52.13

Determination of Standard Enthalpy of Solution of NaOH in Acid

From your graph,         Ti       = __24.2__ °C

         Tf      = _43.6__ °C

Hence        $\Delta$ T    = __19.4__ °C

         q       = – ( Cwater msoln $\Delta$ T) = – 4.184 x _52.13__ x _19.4 __

                   = _4231.37_ J

n = mNaOH / Mr = _1.90_ /40.00 = _0.0475 mol

$\Delta$H° = q/n = _4231.37_ / 0.0475 moles_ = _89081.5_ J/mol = 89.1 kJ/mol