Question

In: Chemistry

1. The molar heat capacity of silver is 25.35 J/mol⋅∘C. How much energy would it take...

1. The molar heat capacity of silver is 25.35 J/mol⋅∘C. How much energy would it take to raise the temperature of 11.9 g of silver by 11.0 ∘C?

2.What is the specific heat of silver?

3.A piston has an external pressure of 8.00 atm. How much work has been done in joules if the cylinder goes from a volume of 0.170 liters to 0.540 liters?

4.Calculate the standard enthalpy change for the reaction

2A+B⇌2C+2D

Use the following data:

Substance	ΔH∘f (kJ/mol)
A	-243
B	-375
C	215
D	-499

Expert Solution

1.

First, you have the molar heat capacity. You want the specific heat capacity.

Molar mass of silver, Ag = 107.9 g/mol

Specific heat capacity of silver = 25.35 J/molC x (1 mol / 107.9 g)

= 0.2349 J/gC

Now, we know that

q = m c T

= 11.9 g x (0.2349 J/g^oC) x (11 ^oC)

= 30.75 J

2.

The molar heat capacity of silver is 25.35 J/mol^oC.

Molar mass of silver, Ag = 107.9 g/mol

Specific heat capacity of silver = 25.35 J/mol^oC x (1 mol / 107.9 g)

= 0.2349 J/g^oC

3.

Work = negative pressure times change in volume.

Work, w = - PV

We know that

1 L x atm = 101.3 J

Pressure, P = 8 atm

Change in volume, V = 0.540 L - 0.170 L = 0.37 L

So, substituting the values, we get

w = - 8 atm x 0.37 L

= - 2.96 L atm

= - 2.96 x 101.3 J

= - 300 J

4.

2A + B ⇌ 2C + 2D

Standard enthalpy change of the reaction

= 2ΔHf°(C) + 2ΔHf°(D) - 2ΔHf°(A) - ΔHf°(B)

= 2(215) + 2(-499) - 2(-243) - (-375)

= 430 - 998 + 486 + 375

= 293 kJ/mol

queen_honey_blossom answered 2 years ago

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