In a constant-pressure calorimeter, 1.60 g of NH4NO3 is mixed with 75.0 g of wat
ID: 958287 • Letter: I
Question
In a constant-pressure calorimeter, 1.60 g of NH4NO3 is mixed with 75.0 g of water at an initial temperature of 25.00 °C. After dissolution of the salt, the final temperature of the calorimeter contents is 23.34°C. Assuming the solution has a heat capacity of 4.18 J/°Cg and assuming no heat transfer between the calorimeter and its surroundings, calculate the enthalpy change for the dissolution of NH4NO3 in units of kJ/mol
(Answer:26.6 kJ/mol) (I know the answer, I just not sure how to use both of the grams when solving the equation, please write your steps so I can try a similar problem on my own. Thank you!)
Explanation / Answer
No of mol of NH4NO3 = 1.6/ 80.0434 = 0.02 mol
q absorbed = m*s*DT
= (75+1.6)*4.18*(25-23.34)
= 531.512 joule
= 0.531 kj
DHrxn = 0.531/0.02 = 26.55 kj/mol