Question #17063

(a) When a 3.88-g sample of solid ammonium nitrate dissolves in 60.0 g of water in a coffee-cup calorimeter (Figure 5.17), the temperature drops from 23.0 oC to

18.4 oc. Calculate H (in kJ/ mol NH4N03) for the solution process

NH4NO3(S) ----> NH4 +(aq) + N03 - (aq)

Assume that the specific heat of the solution is the same as that of pure water.

(b) Is this process endothermic or exothermic?

18.4 oc. Calculate H (in kJ/ mol NH4N03) for the solution process

NH4NO3(S) ----> NH4 +(aq) + N03 - (aq)

Assume that the specific heat of the solution is the same as that of pure water.

(b) Is this process endothermic or exothermic?

Expert's answer

a)

Molar mass of NH4NO3 = 14+4+14+48 = 80 g/mol

So, 3.88 g is equal to

3.88/80 = 0.0485 mol

Now, mass of soln = 60+3.88 g = 63.88 g

Heat absorbed

= 63.88x4.18x(23-18.4) = 1228 J

So, 0.0485 mol absorbs 1228 J

1 mol

absorbs 25319 J

So, heat of dissolution of NH4NO3 is 25.319

kJ/mol

b)

This process is endothermic.

Molar mass of NH4NO3 = 14+4+14+48 = 80 g/mol

So, 3.88 g is equal to

3.88/80 = 0.0485 mol

Now, mass of soln = 60+3.88 g = 63.88 g

Heat absorbed

= 63.88x4.18x(23-18.4) = 1228 J

So, 0.0485 mol absorbs 1228 J

1 mol

absorbs 25319 J

So, heat of dissolution of NH4NO3 is 25.319

kJ/mol

b)

This process is endothermic.

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## Comments

Assignment Expert23.02.18, 17:30Dear Monica Blanco, please use panel for submitting new questions

Monica Blanco21.02.18, 21:59Calculate the minimum value of âˆ†S (J mol-1 K1) associated with dissolving NaNO3 in water at 23oC. For this process âˆ†H=25.41 kJ mol-1.

Assignment Expert04.01.17, 13:51Dear Jake Questions in this section are answered for free. We work on all questions and publish answers after verification. There is no guarantee of answering certain question but we are doing our best. Although if you have serious assignment that requires large amount of work and hence cannot be done for free you can submit it as assignment and our experts will surely assist you.

Jake30.12.16, 18:58It should be exothermic

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