contestada

A 100 mL sample of ethanol at 25°C is mixed with a 300 mL sample of ethanol at -5°C. The mixture is allowed to come to thermal equilibrium. What is the final temperature?

Respuesta :

Answer: The final temperature of the mixture will be [tex]2.5^0C[/tex]

Explanation:

[tex]heat_{absorbed}=heat_{released}[/tex]

As we know that,  

[tex]Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})[/tex]

[tex]m_1\times c_1\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)][/tex]         .................(1)

where,

q = heat absorbed or released

[tex]m_1[/tex] = mass of first sample of ethanol = 100 ml

[tex]m_2[/tex] = mass of second sample of ethanol = 300 ml

[tex]T_{final}[/tex] = final temperature = ?

[tex]T_1[/tex] = temperature of  first sample of ethanol  = [tex]25^oC=298K[/tex]

[tex]T_2[/tex] = temperature of second sample of ethanol  = [tex]-5^oC=268K[/tex]

[tex]c_1[/tex] = [tex]c_2[/tex] = specific heat of ethanol

 Now put all the given values in equation (1), we get

[tex]-100\times (T_{final}-298)=[300\times (T_{final}-268)][/tex]

[tex]T_{final}=275.5K=2.5^0C[/tex]

Therefore, the final temperature of the mixture will be [tex]2.5^0C[/tex]