Question

An unknown substance has a mass of 12.3 g . When the substance absorbs 1.107×102 J of heat, the temperature of the substance is raised from 25.0 ∘C to 45.0 ∘C . What is the most likely identity of the substance?

Answer 1

Heat is equal to product of mass, change in temperature and specific heat.

The formula is given by:

`q=\Delta T* C* m`

where,

q = heat

`\Delta T`= change in temperature that is
`45^(o)C-25^(o)C = 20 ^(o)C`

m = mass of substance

C= specific heat capacity

Put the values,

`1.107* 10^(2) J =20 ^(o)C * C* 12.3 g`

`C= (1.107* 10^(2) J)/(20^(o)C* 12.3 g)`

`C= (1.107* 10^(2) J)/(246^(o)C g)`

=
`0.0045 * 10^(2) J/^(o)C g`

=
`0.45 J/^(o)C g`

Specific heat capacity is equal to
`0.45 J/^(o)C g` and this value corresponds to element iron.

Thus, the unknown substance is iron.