Question

After 0.6 g of CoCl2 x 6H20 is heated, the residue has a mass of 0.339 g. Calculate the % H2O in the hydrate. What was the actual number of moles of water per formula unit CoCl2?

Answer 1

a.) 0.6g-0.339g=0.261g

(0.261g / 0.6g) x 100%= 43.5%

b.) (1 mol CoCl2 / 129.83 g) x (6.022 x 10^23 / 1 mol CoCl2)= 4.638 x 10^21

Part a.) uses knowledge about percent recovery and part b.) uses knowledge of converting 1 mol of a substance to formula units

Answer 2

A. The percentage of water, H₂O in the hydrate is 43.5%

B. The actual number of mole of water per formula unit CoCl₂ is 6 moles

A. How to determine the percentage of water

From the question given above, the following data were obtained:

• Mass of hydrate, CoCl₂•xH₂O = 0.6 g
• Mass of anhydrous, CoCl₂ = 0.339 g
• Mass of water = 0.6 – 0.339 = 0.261 g
• Percentage of water =?

Percentage of water = (mass of H₂O / mass of CoCl₂•xH₂O) × 100

Percentage of water = (0.261 / 0.6) × 100

Percentage of water = 43.5%

B. How to determine the mole of water per formula unit

To obtain the mole of water per formula unit CoCl₂, we shall determine the formula of the hydrate. This can be obtained as follow:

• Percentage of H₂O = 43.5%
• Percentage of CoCl₂ = 100 – 43.5 = 56.5
• Formula =?

Divide by their molar mass

CoCl₂ = 56.5 / 130 = 0.4

H₂O = 43.5 / 18 = 2.4

Divide by the smallest

CoCl₂ = 0.4 / 0.4 = 1

H₂O = 2.4 / 0.4 = 6

Thus, the formula of the hydrate is CoCl₂•6H₂O

Therefore, the mole of water per formula unit CoCl₂ is 6 moles

Learn more about mass composition:

https://brainly.com/question/11617445