How many joules of heat are absorbed to raise the temperature of 435 grams of water at 1 atm from 25°c to its boiling point?

Respuesta :

Answer: 136.6 kJ  

Explanation:

The amount of heat [tex]Q[/tex] absorbed in the temperature variation of a material is:

[tex]Q=m. c. \Delta T[/tex]   (1)

Where:

[tex]m=435g[/tex]  is the mass  of water

[tex]c[/tex]  is the specific heat of the element. In the case of water [tex]c=1 cal/g\°C [/tex]

[tex]\Delta T[/tex]  is the variation in temperature, which in this case is  [tex]\Delta T=100\°C-25\°C=75\°C[/tex]  

(The boiling point of water at the pressure of 1 atm is  [tex]100\°C[/tex])

Rewriting equation (1) with the known values:

[tex]Q=(435g)(1 cal/g\°C)(75\°C)[/tex]  

(2)

[tex]Q=32625 cal[/tex]   (3)

Nevertheless, we are asked to find this value in Joules. So, we have to convert this 32625 calories to Joules, knowing the following:

[tex]1 cal=4.187 J[/tex]   (4)

Hence:

[tex]Q=32625 cal=136600.875 J=136.6kJ[/tex]  

Q&A Education