Question

Copper(II) chloride hydrate, also known as copper chloride hydrate, is the inorganic compound with the chemical formula CuCl2 . x(H2O), where x can range from 1 to 7. A 2.060 g sample of copper (II) chloride hydrate was dissolved in 50.0 mL of deionized water. The concentration of copper (II) ion in the solution was determined spectrophotometrically using the equation from the calibration curve, was 0.200 M. Determine the formula of the copper (II) chloride hydrate.

Answer 1

The formula of the copper(II) chloride hydrate is determined by using the concentration of copper(II) ions in solution and the initial mass of the hydrate. After calculations, the hydrate is found to have approximately 4 moles of water per mole of CuCl2, resulting in the formula CuCl2·4H2O, which is copper(II) chloride tetrahydrate.

Step-by-step explanation:

To determine the formula of the copper(II) chloride hydrate, we start with the given concentration of copper(II) ions in solution. Since the concentration is 0.200 M, this means there are 0.200 moles of copper(II) ions per liter of solution. As we have 50.0 mL, or 0.0500 liters, of solution, this means the total moles of copper in the solution is 0.200 M × 0.0500 L = 0.0100 moles of copper(II) ions.

The initial mass of the copper(II) chloride hydrate was 2.060 g. The molar mass of anhydrous CuCl₂ is 134.45 g/mol, so the mass of CuCl₂ that corresponds to 0.0100 moles is 0.0100 moles × 134.45 g/mol = 1.3445 g. The difference between the initial mass of hydrate and the mass of anhydrous CuCl₂, which is 2.060 g - 1.3445 g, provides the mass of water in the hydrate, which is approximately 0.7155 g.

The molar mass of water (H₂O) is 18.015 g/mol. Therefore, the number of moles of water in the sample is 0.7155 g / 18.015 g/mol = 0.0397 moles. To find the number of moles of water per mole of CuCl₂, we divide the moles of water by the moles of CuCl₂, which gives us 0.0397 moles H₂O / 0.0100 moles CuCl₂ = approximately 4 moles of H₂O. Therefore, the formula of the hydrate is likely CuCl₂·4H₂O, which is copper(II) chloride tetrahydrate.

Answer 2

CuCl₂·4H₂O

Step-by-step explanation:

First we calculate the moles of copper (II) ion in the solution, using the given volume and concentration:

• 50.0 mL ⇒ 50.0/1000 = 0.05 L

• 0.05 L * 0.200 M = 0.01 mol Cu⁺²

For each Cu⁺² mol there's also one CuCl₂ mol.

We convert 0.01 CuCl₂ moles into grams, using its molar mass:

• 0.01 CuCl₂ mol * 134.45 g/mol = 1.344 g

That means that out of the 2.060 g of the sample, 1.344 g are of CuCl₂. This means that there are (2.060 - 1.344) 0.716 g of water.

We convert those 0.716 g of water to moles:

• 0.716 g ÷ 18 g/mol = 0.04 mol H₂O

There are four times as many H₂O moles as there are CuCl₂ moles. This means the formula is CuCl₂·4H₂O