Engineering
Chemistry
First Law and Various Process
Heat Work and internal Energy
Question

An ideal gas undergoes isothermal compression from 5 m3 to 1 m3 against a constant external pressure of 4 Nm–2. Heat released in this process is used to increase the temperature of 1 mole of Al. If molar heat capacity of Al is 24 J mol–1 K–1, the temperature of Al increases by:

2/3 K

3/2 K

2 K

4 K

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Solution

Isothermal ⇒ ΔU=0

so        q = – wirr

            = + Pext. (V2 – V1)

            = 4 (1 – 5)

            = –16 J

For Al

           q = n.Cm.ΔT

           16 = 1 × 24 × ΔT

           ΔT = 23K