Question

Suppose that 0.83 g of water condenses on a 85.0 g block of iron that is initially at 20 ?C.

If the heat released during condensation goes only to warming the iron block, what is the final temperature (in ?C) of the iron block? (Assume a constant enthalpy of vaporization for water of 44.0kJ/mol.)

Answer 1

Given:

Enthalpy of vaporisation of waterH^ovap44.0KJ/mol

mol of watermass of water/molar mass0.83g/18.0g/mol0.0461mol

Heat released by water(Qw)H^ovap*0.0461mol(44.0KJ/mol)*(0.0461mol)2.029 KJ

Equation to be used for calculation:

Heat released by water(Qw)heat gained by iron block(QFe)

or , heat gained by iron block(QFe)mass of iron(mFe)*Specific heat of iron(CFe)* change of temperature(TTf-Ti)

                                                    (85.0g)*(0.450J/gC)*(Tf-20 C)

or,Heat released by water(Qw)2.029 KJ(85.0g)*(0.450J/gC)*(Tf-20 C)

or ,2.029 *1000J(85.0g)*(0.450J/gC)*(Tf-20 C)

or, (Tf-20 C)(2.029 *1000J)/((85.0g)*(0.450J/gC))53.046

or, (Tf-20 C)53.046

Tf53.046-2033.046 deg C

Tf or final temperature of iron block is 33 .0 deg C