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3. A molten metal of mass 150 g is kept at its melting point 800°C. When it is allowed to freeze at thesame temperature, it gives out 75,000 J of heatenergy(a) What is the specific latent heat of the metal ?(b) If the specific heat capacity of metal is200 J kg-1 K-1, how much additional heatenergy will the metal give out in cooling to- 50 °C ? |
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Answer» Explanation:Let L be the latent specific heat of the METAL. When the metal is allowed to be solidified its MP i.e. 800 ∘ C, it will give out latent heat only. mL=75000 0.150×L=75000 L=500000Jkg −1 Now, Heat given out by the metal in cooling down to −50 ∘ C. Fall in temperature will be 800 ∘ C−(−50 ∘ C)=850 ∘ C Heat given out= m×s×t=(0.150×200×850)=25500J |
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