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What mass of ethyl alcohol will give up 33,000 J of energy as it cools from 27°C to...

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melissazamora7 | Student, Grade 11 | Honors

Posted November 21, 2012 at 7:36 PM via web

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What mass of ethyl alcohol will give up 33,000 J of energy as it cools from 27°C to -3°C?

a. 1.92×109kg

b. 2.41x109kg

c. 0.566kg

d. 0.453k


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jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted November 21, 2012 at 11:21 PM (Answer #1)

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Specific heat capacity of Ethanol is 2440J/(kg.K)

Boiling point of ethanol is 78.37C and Melting point is -114C. Therefore the heat exchange will be on liquid state completely. No change of state occurs.

 

If the ethanol mass is m

Using `Q = mCtheta`

-33000 = m*2440*(-3-27)    (-) is for give up energy

        m = 0.45kg

 

So the answer is d.

 

 

 

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