1 mole of `Fe_(2)O_(3) and ` 2 mole of Al are mixed at temperature `25^(@)C` and the reaction is completedto give:
`Fe_(2)O_(3)(s)+2Al(s)toAl_(2)O_(3)(s)+2Fe(l),DeltaH=-850kJ`
The liberated heat is retained within the products, whose combined specific heat over a wide temperature range is about `0.8Jg^(-1)K^(-1)`. The melting point of iron is `1530^(@)C`. Show that the quantity of heat liberated is sufficient to raise the temperature of the product to the melting point of iron in order to get it welded.

Explanation

Mass of products
=Mass of one mole `Al_(2)O_(3)`+Mass of two mole Fe ltBrgt `=214g`
`q=msDeltaT=214xx0.8xx(1803-298)`
`=-257656J=257.656kJ`
Heat requried is less than heat released, hence the temperature can be easily raised to the required value.