Question

A 7.41 g sample of an unknown salt (MM = 116.82 g/mol) is dissolved in 15.00 g water in a coffee cup calorimeter. Before placing the sample in the water, the temperature of the salt and water is 23.72 degrees celsius. After the salt has completely dissolved, the temperature of the solution is 28.54 degrees celsius.

A) Was the dissolution process endothermic or exothermic?

B) What is the heat for the dissolution reaction?

Answer 1

riven, The amount of the sample unknown salt: 72419 (MH = 116829/mol) Alomount of solvent waten) - 15.00gon Initial temperature = 33.73 degrees = 273 +23:42 = 296'72 Kelvin Final temperature = 98:54 degree = 273 +22°54 = 30154 Kelvin Specific heat of water (solvent) = 4°186 jouele qiram liven rross, di sample Number of moles of sample = a Molam mass of sample = = 116°82 = 0.0611 Now, Heat of dissolution is given by 49 = msat m= reasons O moles of the sample = msat s= specific heat = 0.0611 X 4'1864 (30154 AT = 'Chenet ir - 296*72) temiperature - 1033 joule This is the omount of treat given out $6. Reaction is exothermie (49 =')