1) if the temperature of 100mL of water rises from 25.0 C to 32.0 C, how much he

Question

1) if the temperature of 100mL of water rises from 25.0 C to 32.0 C, how much heat was added? Assume the density of water is 1.00g/mL and specific heat capacity of the water is 4.184J/g C. Include units and use the correct number of significant figures.

2) Show using Hess's Law how the enthalpy of reaction for HCl + NaOH [you don't need specific numbers, just call it (delta Hx)] minus the enthalpy of the reaction for HCl + NH3 (call it (deltaHy)) should be equal to the enthalpy of reaction for NaOH + NH4Cl. Show all work

Explanation / Answer

Heat added = m*c*delta T

heat added = (100*1) * 4.184*(32-25)

heat aded = 2926.7 J

2)we know,

NaOH + HCl = NaCl +H2O......Hx(1)

NH3 + HCl = NH4Cl.......Hy(2)

NaOH + NH4Cl= NaCl + NH3.........(3)

we can see,

subtrcting (1)-(2),

we get three,

hence, (3)is occuring in two steps , (1) and the reverse of (2),

hence heat of reaction of (3) = Hx +(-Hy) = Hx-Hy

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