Question

Converstion of one mole of gypsum to one mole of plaster of Paris the percentage lose in weight?

Answer 1

Answer:

27 grams

Explanation:

Given:

No of moles of gypsum = 1 mole

No of moles of Plaster of Paris = 1 mole

To Find:

The decrease in mass when this conversion takes place.

Calculation:

- The formula of gypsum is CaSO4.2H2O.

- The formula of Plaster of Paris is CaSO4.1/2H2O.

- The conversion takes place as follows:

CaSO4.2H2O + Heat → CaSO4.1/2H2O + 3/2 H2O

- So, 3/2 moles of water leaves from it.

- The molar mass of water = 18 gm

⇒ Mass of 3/2 moles = 18 × 3/2 = 27 gm

- So, 27 grams of mass decrease is observed on converting 1 mole of gypsum into 1 mole of Plaster of Paris.

Hope it helps....

Answer 2

Moles of gypsum = 1 mole

Moles of Plaster of Paris = 1 mole

To Find: Percentage loss in weight

Gypsum = CaSO4.2H2O

Plaster of Paris = CaSO4.1/2H2O

Equation for conversion

$\ce{CaSO4.2H2O + Heat - > CaSO4.1/2H2O + 3/2 H2O }$

Mass of Gypsum = Molar mass x Moles

                             = 172 x 1 = 172

Mass of Plaster of Paris = Molar Mass x Moles

                                         = 145 x 1 = 145

Mass lost = 172 - 145 = 27

% loss = $27\div 172$ x $100$ = 15.697

Hence the percentage loss is 15.697%

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