In today\'s workshop we will use calorimetry to calculate the standard malar ent

Question

In today's workshop we will use calorimetry to calculate the standard malar enthalpy of reaction or the enthalpy change that occurs in a system when 1 mole of matter is transformed by a chemical reaction at 1 atm: AH (in J/mol, at constant pressure and pV-work only), where q cmAT Let's consider the following chemical experiment: A student wants to measure the heat of neutralization reaction. To do this she mixed in a coffer cup calorimeter 35.0 ml, of 0.70M HCl solution and 65.0 ml, of 0.50M NaoH solution both at 22.0oC initially. She then continued to measure the temperature of the mixture for 10 minutes.

Explanation / Answer

Calorimetry

(a) The final temperature of the mixture = Tf = 25.2 oC

Initial temperature = 22 oC

change in temperature dT = 25.2 - 22 = 3.2 oC

The system has lost energy to the surrounding

(b) heat transferred between system and surrounding = q = mCpdT

= 100 x 4.184 x 3.2

= 1338.88 J

(c) molar heat of neutralization dH

= q/n

= 1338.88/0.7 M x 35 ml

= 54.65 kJ/mol

(d)The neutralization reaction is exothermic in nature as the final temperature of the system is higher than the initial temperature.

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