Question

Lab observations :

Exp 2 Empty mass of crucible 88.00 Added 5g of Magnesium Chloride hydrate to crucible

Total mass of crucible and Magnesium Chloride hydrate 93.000 A gray/ white solid is present prior to heating heated under bunsen burner

White vapor is produced No change in color/ appearance

Mass of crucible and left over contents after heating 90.342

1)How many grams of anhydrous magnesium chloride were in the crucible after heating? Choose the closest answer.

2)How many grams of water were lost during the heating process? Choose the closest answer.

3)How many moles of water were lost during the heating? The molar mass of water is 18.015 g/mol. Choose the closest answer.

4)How many moles of anhydrous magnesium chloride remained in the crucible after heating? The molar mass of anhydrous magnesium chloride is 95.211 g/mol. Choose the closest answer.

5)In Experiment 2, which of the following represents the balanced chemical equation for this reaction?

6)Why was mass lost from the crucible during the reaction? 7)Calcium sulfate is a white solid found as two hydrates, a hemihydrate known as plaster of Paris and a dehydrate known as gypsum. The hemihydrate is a white solid as shown in the figure below. Given that the molar mass of the anhydrous calcium sulfate is 136.14 g/mol, the molar mass of the hemihydrate is 145.15 g/mol, and the molar mass of water is 18.015 g/mol, what is the empirical formula of the hemihydrate?

Answer 1

Given Data,

Empty mass of crucible 88.00 gram

5g of Magnesium Chloride hydrate to crucible

Total mass of crucible and Magnesium Chloride hydrate 93.000 grams

Mass of crucible and left over contents after heating 90.342 grams

molar mass of water is 18.015 g/mol.

molar mass of anhydrous magnesium chloride is 95.211 g/mol

Q1. Answer:

Mass of anhydrous Magnesium chloride is

= (Mass of crucible and left over contents after heating) - Empty mass of crucible

= 90.342-88.00

=2.342 g of Anhydrous Magnesium chloride

Q.2 Answer.

Water lost = (mass of Magnesium Chloride hydrate)- (Mass of        Anhydrous Magnesium chloride)

=5.000-2.342 g

=2.658 g of water lost during heating process

Q.3. Answer

molar mass of water is 18.015 g/mol

No of moles of Water lost during heating process is

1 Moles of water is = 18.015g

N moles of water lost= 2.658g         , Cross multiplication

N = ( 1 Moles of water is) x (2.658)

                          18.015

= 0.1475 moles of water lost during heat

Q4. Answer.

Moles of anhydrous magnesium chloride remained in the crucible after heating=

2.342 g of Anhydrous Magnesium chloride is remained

Therefore, no. Of moles is =

1 mole= 95.211 g

N moles= 2.342g

N= 1x2.342

      95.211

= 0.0246 moles of Anhydrous Magnesium chloride is remained

Q5. Answer

Balanced chemical reaction

           Q. 6 Answer

The empirical formula is CaSO₄.

The empirical formula tells us the simplest whole-number ratio of the different types of atoms in a compound.

We know that the molecular formula of calcium sulfate is CaSO₄.

To get the empirical formula, we divide the subscripts by their highest common factor (1).

This gives you the empirical formula CaSO₄.