a) It takes 47.0J to raise the temperature of an 10.7g piece of unknown metal from 13.0∘C to 25.0∘C. What is the specific heat for the metal?
b) The molar heat capacity of silver is 25.35 J/mol⋅∘C. How much energy would it take to raise the temperature of 10.7g of silver by 15.2∘C?
c) What is the specific heat of silver?

Respuesta :

Giovi
The heat Q can be evaluated as:
Q=mcΔT
where:
m is the mass
c specific heat
ΔT change in temperature.
So:
a)
47=10.7c(25-13)
c=0.39 J/g°C
Using the same idea you get (I transformed g into moles using the molar mass of silver from the table of elements):
b) Q=(10.7/107.9)×25.35×15.2=38.21 J
where: Molar mass of Ag = 107.8682 g/mol
c) 38.21=10.7c15.2
c=specific heat of silver=0.235 J/g°C

Answer:

a) 0.3660 J/g°C is the specific heat for the metal.

b) 37.7 Joules energy would it take to raise the temperature of 10.7 grams of silver by 15.2°C.

c)The specific heat of silver is 0.2347 J/g°C.

Explanation:

Energy required to raise the temperature,Q = 47.0 J

Mass of the unknown metal = m = 10.7 g

Change in temperature = ΔT =  25.0°C - 13.0°C  = 12°C

Specific heat of metal = c

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

[tex]47.0 J=10.7 g\times c\times 12^oC[/tex]

[tex]c=\frac{47.0 J}{10.7 g\times 12^oC}=0.3660 J/g^oC[/tex]

0.3660 J/g°C is the specific heat for the metal.

b) The molar heat capacity of silver  = [tex]c_m=25.35 J/mol^oC[/tex]

Molar mass of silver ,M= 108 g/mol

Specific heat of silver = c = [tex]\frac{c_m}{M}=-\frac{25.35 J/mol^oC}{108 g/mol}=0.2347 J/g ^oC[/tex]

Given mass of silver = m = 10.7 g

Change in temperature = ΔT = 15°C

Energy required to raise the temperature of silver = Q

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

[tex]Q= 10.7 g\times 0.2347 J/g ^oC\times 15^oC[/tex]

Q = 37.7 Joules

37.7 Joules energy would it take to raise the temperature of 10.7 grams of silver by 15.2°C.

c) The specific heat of silver is calculated in (b) part above.

Specific heat of silver = c = [tex]\frac{c_m}{M}=-\frac{25.35 J/mol^oC}{108 g/mol}=0.2347 J/g ^oC[/tex]