Question

Describe how to test the filtrate for the presence of excess Na3PO4•12H2O.

Answer 1

Describe how to test the filtrate for the presence of excess Na3PO4•12H2O.

The filtrate must be dried; then

the salt + hydrate will be present only, no moisture is left

for H2O hydrate = in an oven about to 120 C; ekep the salt until steady weight is achieved

initial measurement = Hydrated salt i.e. = Salt + X H2O

after heating = Salt dehydrated = Salt

test for water = Initial - After weights = Mass of Water vaporized

relate mol ratios

For

NA --> Use flame test, it should giv ea red/organge color

For

PO4-3 ; you can use either:

Ca+2 or Ba+2 ions,

The phosphate will precipitate in order to form the phosphate salt

Ca3(PO4)2 or Ba3(PO4)2 should form