When a 0.326 g sample of FeCl2·xH2O is heated to remove all water, a mass of 0.254 g remains. Determine the value of x.
0.326 g = mass FeCl2.xH2O
-0.254 g = mass FeCl2
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0.072 g = mass xH2O
mols FeCl2 = grams/molar mass = ?
mols H2O = grams/molar mass = ?
Now find the ratio of 1 mol FeCl2 to H2O and round to a whole number. That whole number will be x.
The easy way to do that is to divide mols FeCl2 by itself (thereby getting 1.000); then divide the mols H2O by the same number. The resulting answer will be x.
To determine the value of x in FeCl2·xH2O, we need to analyze the given information.
First, we know that 0.326 g of FeCl2·xH2O is initially present. When this sample is heated to remove all water, a mass of 0.254 g remains.
To find the amount of water in the compound, we subtract the final mass (0.254 g) from the initial mass (0.326 g) of the sample:
Mass of water = Initial mass - Final mass
= 0.326 g - 0.254 g
= 0.072 g
Now, we can determine the molar mass of water (H2O), which consists of two hydrogen atoms (H) and one oxygen atom (O).
Molar mass of H2O = (2 × molar mass of H) + molar mass of O.
The molar mass of hydrogen (H) is approximately 1.0079 g/mol, and the molar mass of oxygen (O) is approximately 15.999 g/mol.
Therefore, the molar mass of water (H2O) is:
Molar mass of H2O = (2 × 1.0079 g/mol) + 15.999 g/mol
= 18.015 g/mol
Now, let's calculate the number of moles of water (H2O) in the sample:
Number of moles of water = mass of water / molar mass of water
= 0.072 g / 18.015 g/mol
≈ 0.00399 mol
Finally, x can be determined by comparing the molar ratio between FeCl2 and H2O in the compound FeCl2·xH2O.
From the compound's formula, we can see that for every one mole of FeCl2, there are x moles of H2O.
Since we have determined that there are approximately 0.00399 moles of water, we can assert that:
1 mole of FeCl2 = x moles of H2O
1 mole = x * 0.00399 moles
x = 1 / 0.00399
x ≈ 250.63
So, the value of x is approximately 250.63.