Question

Для определения кристаллизационной воды в кристаллогидрате нитрата меди взята проба 0.9664 г. По удалении кристаллизационной получено 0.7504 нитрата меди. Вычислить число молекул воды в кристаллогидрате. Помогите пожалуйста.

Answer 1

Cu(NO3)2*nH2O=Cu(NO3)2+nH2O
0.9664/188+18n=0.7504/188
n=3
Cu(NO3)2*3H2O

Answer 2

To determine the number of water molecules in the copper nitrate hydrate crystal, we can use the principle of conservation of mass. The mass of the water can be calculated by subtracting the mass of the anhydrous copper nitrate from the mass of the hydrated copper nitrate.

Given: - Mass of the sample = 0.9664 g - Mass of the anhydrous copper nitrate = 0.7504 g

To calculate the mass of water, we can subtract the mass of the anhydrous copper nitrate from the mass of the sample:

Mass of water = Mass of sample - Mass of anhydrous copper nitrate

Mass of water = 0.9664 g - 0.7504 g = 0.216 g

Now, to calculate the number of water molecules, we can use the molar mass of water and Avogadro's number.

The molar mass of water (H2O) is approximately 18.015 g/mol.

To calculate the number of water molecules, we can use the following formula:

Number of water molecules = Mass of water / Molar mass of water * Avogadro's number

Number of water molecules = 0.216 g / 18.015 g/mol * 6.022 x 10^23 molecules/mol

Calculating this, we find:

Number of water molecules ≈ 6.78 x 10^22 molecules

Therefore, there are approximately 6.78 x 10^22 water molecules in the copper nitrate hydrate crystal.

Please note that the above calculation assumes that the only component of the crystal is water. If there are other components present, the calculation may vary.