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In a coffee-cup calorimeter, 55.0 mL of 0.100 M AgNO3 and 55.0 mL of 0.100 M HCl are mixed to yield the following reaction.

Ag+(aq) + Cl −(aq) → AgCl(s)
The two solutions were initially at 22.88°C, and the final temperature is 23.68°C. Calculate the heat that accompanies this reaction in kJ/mol of AgCl formed. Assume that the combined solution has a mass of 110.0 g and has a specific heat capacity of 4.18 J/°C · g.
kJ/mol

1 Answer

4 votes

Answer:

Step-by-step explanation:

To calculate the heat of the reaction in kJ/mol of AgCl formed, we can use the concept of calorimetry and the equation for heat transfer:

=

Δ

q=m⋅c⋅ΔT

Where:

q is the heat transfer (in Joules).

m is the mass of the solution (in grams).

c is the specific heat capacity of the solution (in J/°C·g).

Δ

ΔT is the change in temperature (in °C).

First, we need to calculate the change in temperature (

Δ

ΔT):

Δ

=

ΔT=T

f

−T

i

Where:

T

f

is the final temperature.

T

i

is the initial temperature.

Δ

=

23.68

°

22.88

°

=

0.80

°

ΔT=23.68°C−22.88°C=0.80°C

Next, we'll calculate the mass of the solution (

m):

Since you have 55.0 mL of 0.100 M AgNO3 and 55.0 mL of 0.100 M HCl, you have a total volume of 110.0 mL (0.110 L) of the solution.

The density of the solution is typically close to the density of water, which is approximately 1 g/mL.

So, the mass of the solution is:

=

110.0

m=110.0g

Now, we'll calculate the heat transfer (

q):

=

Δ

q=m⋅c⋅ΔT

=

110.0

4.18

/

°

0.80

°

q=110.0g⋅4.18J/°C⋅g⋅0.80°C

=

369.872

q=369.872J

Now, we need to convert the heat from Joules to kJ:

=

369.872

1

1000

=

0.369872

q=369.872J⋅

1000J

1kJ

=0.369872kJ

Now, we can calculate the heat per mole of AgCl formed. The balanced chemical equation shows that one mole of AgCl is formed from one mole of Ag+ and one mole of Cl-. Since the initial concentrations of AgNO3 and HCl were both 0.100 M, they are 1:1 in the reaction.

So, for every 0.100 moles of AgNO3 and 0.100 moles of HCl, we form 0.100 moles of AgCl.

Now, we can calculate the heat in kJ/mol of AgCl formed:

Heat per mole of AgCl

=

0.369872

0.100

=

3.69872

/

Heat per mole of AgCl=

0.100moles

0.369872kJ

=3.69872kJ/mol

So, the heat that accompanies this reaction in kJ/mol of AgCl formed is approximately 3.70 kJ/mol.

User Lars Moelleken
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