A 2.50g sample of a hydrate of calcium nitrate was heated, and only 1.70g of the anhydrous salt remained. what is the formula of the hydrate?

To find the formula of the hydrate, we need to determine the number of water molecules present in the original compound before it was heated.

1. Calculate the mass of water lost during heating:
Mass of water lost = Mass of hydrate - Mass of anhydrous salt
Mass of water lost = 2.50g - 1.70g = 0.80g

2. Determine the number of moles of water lost:
Moles of water lost = Mass of water lost / molar mass of water
Molar mass of water = 18.015 g/mol (molar mass of oxygen (16.00 g/mol) + 2 * molar mass of hydrogen (1.01 g/mol))
Moles of water lost = 0.80g / 18.015 g/mol ≈ 0.044 mol

3. Since calcium nitrate contains two nitrate ions (NO3-) per formula unit, it must have two water molecules per formula unit.

4. Calculate the number of moles of calcium nitrate remaining after heating:
Moles of calcium nitrate = Mass of anhydrous salt / molar mass of anhydrous salt
Molar mass of anhydrous salt = molar mass of calcium (40.08 g/mol) + 2 * molar mass of nitrogen (14.01 g/mol) + 6 * molar mass of oxygen (16.00 g/mol)
Molar mass of anhydrous salt = 164.09 g/mol
Moles of calcium nitrate = 1.70g / 164.09 g/mol ≈ 0.010 mol

5. Divide the number of moles of water lost by the number of moles of calcium nitrate to determine the mole ratio of water to calcium nitrate:
Mole ratio of water to calcium nitrate = Moles of water lost / Moles of calcium nitrate
Mole ratio of water to calcium nitrate = 0.044 mol / 0.010 mol = 4.4

6. Since we cannot have a fraction in a chemical formula, we multiply both the water and the calcium nitrate by 5 to get whole numbers.
Mole ratio of water to calcium nitrate (multiplied by 5) ≈ 4.4 * 5 = 22

Therefore, the formula of the hydrate of calcium nitrate is Ca(NO3)2· 22H2O.

To find the formula of the hydrate, we need to calculate the moles of both the hydrated and anhydrous salts. Then, we can determine the ratio of moles and use that to determine the formula.

1. Calculate the moles of the anhydrous salt:
Moles of anhydrous salt = mass of anhydrous salt / molar mass of anhydrous salt

In this case, the mass of the anhydrous salt is 1.70g. To calculate the molar mass of the anhydrous salt, which is calcium nitrate (Ca(NO3)2), we add the atomic masses of calcium (Ca), nitrogen (N), and three times the atomic mass of oxygen (O):

Molar mass of Ca(NO3)2 = atomic mass of Ca + 2 × (atomic mass of N + 3 × atomic mass of O)

2. Calculate the moles of the hydrated salt:
Moles of hydrated salt = mass of hydrate - mass of anhydrous salt / molar mass of water

In this case, the mass of the hydrate is given as 2.50g. The molar mass of water (H2O) is determined by adding the atomic masses of hydrogen (H) and oxygen (O).

3. Determine the ratio of moles of anhydrous salt to moles of water:
Ratio = Moles of anhydrous salt / Moles of water

4. Simplify the ratio to whole numbers (if necessary):
Divide the ratio by the smallest number of moles you calculated to get a whole number ratio.

5. Use the simplified ratio to write the formula of the hydrate:
The formula of the hydrate will be (anhydrous salt) ± nH2O, where "n" is the simplified ratio.

By following these steps, you should be able to determine the formula of the hydrate of calcium nitrate.

Plz explain clearly

Ca(NO3)2.xH2O ==> Ca(NO3)2 + xH2O

...2.50g.........1.70.......0.80

mols Ca(NO3)2 = 1.70/164 = about 0.0104
mols H2O = 0.044
0.0444/0.0104 = 4.3. Usually these come out closer to whole numbers than this. Check the figures.