263 g sample of a hydrate of magnesium chromate, MgCrO4xH2O, was heated gently at 200 C in an evaporating dish. The sample was heated twice, for 5...

A

4.263 g sample of a hydrate of magnesium chromate,

MgCrO4•xH2O, was heated gently at 200 ̊C in an evaporating dish. The sample was heated twice, for 5 minutes each, until a constant mass was obtained. The

mass of the anhydrous salt (i.e. without water),

MgCrO4, was found to be 2.595 g.

a)

Calculate the percent by mass of water in the sample.

b)Calculate the moles of H2O removed by heating.

c)Calculate the moles of MgCrO4remaining in the evaporating dish.

d)Use your answers to parts b and c to determine x (as a decimal number with appropriate sig figs)=the mole ratio of water to anhydrous salt.

e) Write the formula of this hydrate, using x rounded to an integer.