What is the percentage of water in the hydrate cocl2 • 6h2o? can someone me with this one?

Okay, to do this you have to work with the relative molecular mass (RMM). You can get this from looking at the periodic table.

The RMM for the whole molecule is:
58.933 + (2 x 35.453) + (12 x 1.008) + (6 x 15.9994) = 237.96

Then you work out the RMM for water:
(2 x 1.008) + 15.9994 = 18.0154

As there are 6 moles of water in this molecule then multiply the RMM of H2O by 6 = 108.0924

Finally, divide the total H2O RMM by the total molecule RMM and multiply by 100 to get a percentage:
(108.0925 / 237.96) x 100 = 45.42%

Neither model is able to show the reactivity of potassium.