Calculating Latent Heat of Water Vaporization

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Homework Statement

from the following observations made during an experiment, determine the specific latent heat of vaporisation of water.

initial mass of water 400g, final mass of water 450g (the extra is condensed steam)

mass of calorimeter 200g, initial temp of water & calorimeter 16 C

final temp of water & calorimeter 70 C , specific heat capacity of water 4200j/kg C

specific heat capacity of calorimeter 420 j/kg C

HINT heat lost by steam= heat gained by water + heat gained by calorimeter

Homework Equations

quantity of heat = mass x specific heat capacity x temperature change

The Attempt at a Solution

let suffix c = calorimeter
w = water

mc cc tc = mw cw tw + fmw cw t

-200 x 420 ( 70 tc) = 400 x 4200 ( 16 t) + 450 x 420 ( 16 t)

- 84000 ( 70 tc) = 168,0000 ( 16 t) + 189,000 (16 t)

-84000 ( 70 tc) = 1869000 ( 16 t)

- 84000 c + 5.88 x 10 6 = 1869000 c 29.904 x 10 6

5.88 x 10 6 +29.904 x 10 6 = 1869000 c 84000 c


35.784 x 10 6 = c (1869000 + 84000 ) = 1953000 c


c = 35.784 x 10 6 / 1953000 = 18.322 C


MY TUTOR HAS SAID MY FORMULA IS INCOMPLETE BUT I DONT NO WHERE I HAVE GONE WRONG PLEASE HELP MARK.

 

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can anyone help ?