If 1.6045g of anhydrous salt remains after heating 1.9045 g of CuC§¤2¡¤xH2O, determine the number of molecules of water of hydration in the original hydrate
I guess that is CuC2 hydrated with x H2O
CuC2 = 63.5 + 24 = 87.5 grams/mol
so
1.6045 grams * 1 mol/87.5 grams
= .0183 mol of CuC2
H2O = 18 grams/mol
we have how many mols of H2O?
1.9045 - 1.6045 = 0.3 grams H2O
so
0.3 / 18 = .01667 mol H2O
looks like about as many mols of H2O as of CuC2 like 183/167 = 1.01
and x = 1
To determine the number of molecules of water of hydration in the original hydrate, we can use the concept of stoichiometry.
1. Start by finding the mass of water lost during heating. Subtract the mass of the anhydrous salt (1.6045 g) from the mass of the original sample (1.9045 g):
Mass of water lost = Mass of original sample - Mass of anhydrous salt
= 1.9045 g - 1.6045 g
= 0.3 g
2. Next, we need to convert the mass of water lost into moles. To do this, we need to know the molar mass of water. The molar mass of water (H2O) is approximately 18 g/mol (2 g/mol for hydrogen + 16 g/mol for oxygen).
Moles of water lost = Mass of water lost / Molar mass of water
= 0.3 g / 18 g/mol
≈ 0.0167 mol
3. Now we need to find the number of moles of water of hydration in the original hydrate. From the chemical formula CuCO3·xH2O, we can see that the ratio of moles of water to moles of CuCO3 is 1:x. In other words, for every mole of CuCO3, there are x moles of H2O.
Since we have the mass of CuCO3 (1.9045 g), we can find the moles of CuCO3 using its molar mass. The molar mass of CuCO3 is approximately 123.5 g/mol (63.5 g/mol for Cu + 12 g/mol for C + 3(16 g/mol) for O).
Moles of CuCO3 = Mass of CuCO3 / Molar mass of CuCO3
= 1.9045 g / 123.5 g/mol
≈ 0.0154 mol
4. Now we can use the ratio of moles of H2O to moles of CuCO3 to find the number of moles of water of hydration.
Moles of water of hydration = Moles of CuCO3 * x
Since we're looking for the number of molecules of water, not moles, we need to multiply the moles of water of hydration by Avogadro's number, which is approximately 6.022 x 10^23 molecules/mol.
To summarize, the number of molecules of water of hydration in the original hydrate is:
Number of molecules of water = (Moles of CuCO3 * x) * Avogadro's number
You need to know the value of x from the formula CuCO3·xH2O to get the exact number of molecules of water of hydration in the original hydrate.