In an experiment a student mixes a 50.0 mL sample of 0.100 M AgNO₃(aq) with a 50.0 mL sample of 0.100 M NaCl(aq) at 20.0°C in a coffee-cup calorimeter.
What is the enthalpy change of the precipitation reaction represented above if the final temperature of the mixture is 21.0°C?
(Assume that the total mass of the mixture is 100. g and that the specific heat capacity of the mixture is 4.2 J/(g°C)).

Respuesta :

The enthalpy change of the precipitation reaction is 84 kJ/mole

Why?

The chemical equation for the reaction is

AgNO₃(aq) + NaCl (aq) → AgCl(s) + NaNO₃(aq)

To find the enthalpy change we need to apply the following equation

[tex]\Delta H =\frac{Q}{n}[/tex]

To find the heat (Q):

[tex]Q=m*C*\Delta T=(100g)*(4.2 J/g*^\circ C)*(21^\circ C-20^\circ C)\\\\Q=420J[/tex]

Now, to find the number of moles that react (n):

[tex]n=[AgNO_3]*v(L)=(0.1M)*(0.05L)=0.005moles[/tex]

Having these two values we can plug in the first equation:

[tex]\Delta H= \frac{420J}{0.005moles}=84000J/mole=84kJ/mole[/tex]

Have a nice day!

The change in enthalpy for the reaction has been 84 kJ/mol.

The chemical equation for the reaction will be:

[tex]\rm AgNO_3\;+\;NaCl\;\rightarrow\;AgCl\;+\;NaNO_3[/tex]

The enthalpy change can be given as the ratio of heat to moles.

Moles of Silver nitrate = molarity [tex]\times[/tex] volume

Moles of Silver nitrate = 0.1 [tex]\times[/tex] 0.05 L

Moles of Silver nitrate = 0.005 moles.

Heat can be given by:

Q = mc[tex]\Delta[/tex]T

m = mass = 100 grams

c = specific heat capacity = 4.2 J/g[tex]\rm ^\circ C[/tex]

[tex]\Delta[/tex]T = change in temperature = 21 [tex]\rm ^\circ C[/tex] - 20 [tex]\rm ^\circ C[/tex] = 1 [tex]\rm ^\circ C[/tex]

Q = 100 [tex]\times[/tex] 4.2 [tex]\times[/tex] 1

Q = 420 J

The enthalpy change ([tex]\Delta[/tex]H) can be given by:

[tex]\Delta[/tex]H = [tex]\rm \dfrac{Heat}{moles}[/tex]

[tex]\Delta[/tex]H = [tex]\rm \dfrac{420}{0.005}[/tex]

[tex]\Delta[/tex]H = 84000 J/mol

[tex]\Delta[/tex]H = 84 kJ/mol

The change in enthalpy for the reaction has been 84 kJ/mol.

For more information about enthalpy change, refer to the link:

https://brainly.com/question/1477087