Question

What mass of water is present in 3.87 g of copper(II)
chloride tetrahydrate? (MM = 206.53)
A) 0.349 g
B) 0.337 g
C) 1.35 g
D) 1.69 g
E) 2.52 g

Answer 1

Answer:

Option ; C

Explanation:

Let us first write the chemical equation in order to find the mole ratio relationship

CuCl2 + 4 H2O == CuCl24H20

Here we can see that one mole of CuCl2 combines with 4 moles of water.

Now molar mass of copper chloride tetrahydrate is 206.53

Molar mass of water = 18

Molar mass of water in copper chloride tetrahydrate = 72

Percentage of water in copper chloride tetrahydrate = 72/206.53 x 100 = 34.86%

Using simple percentage distribution formula;

Mass of water in copper chloride tetrahydrate = 3.87 x 34.86% = 1.35g

Answer 2

Given:

The mass of copper (II)  chloride tetra-hydrate = 3.87 g

Molar mass = 206.53 gm

To Find:

The mass of water present in the given mass of copper (II)  chloride tetra-hydrate.

Calculation:

- Since the given compound is a tetra hydrate;

⇒ Amount of water in 206.53 g of copper (II)  chloride tetra-hydrate = 72 gm

⇒ Amount of water in 3.87 g of copper (II)  chloride tetra-hydrate = (72/206.53) × 3.87

⇒ Amount of water in 3.87 g of copper (II)  chloride tetra-hydrate = 1.35 gm

- So, the mass of water present in 3.87 g of copper (II)  chloride tetra-hydrate  is 1.35 gm.

- Hence, the correct answer is (C) 1.35 g.