1.62 g of CoCl2 x (xH20) were heated. After heating only .88g of CoCl2 remained. What was the formula of the original hydrate?
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To determine the formula of the original hydrate, we need to calculate the number of water molecules (x) associated with CoCl2.
1. Calculate the mass of CoCl2 left after heating:
Mass of CoCl2 left = 0.88 g
2. Calculate the mass of water lost during heating:
Mass of water lost = Mass of original hydrate - Mass of CoCl2 left
Mass of water lost = 1.62 g - 0.88 g
Mass of water lost = 0.74 g
3. Determine the number of moles of CoCl2 left:
Molar mass of CoCl2 = 58.933 g/mol (cobalt chloride)
Number of moles of CoCl2 left = Mass of CoCl2 left / Molar mass of CoCl2
Number of moles of CoCl2 left = 0.88 g / 58.933 g/mol
4. Calculate the number of moles of water lost:
Molar mass of water = 18.015 g/mol
Number of moles of water lost = Mass of water lost / Molar mass of water
Number of moles of water lost = 0.74 g / 18.015 g/mol
5. Find the mole ratio of CoCl2 to water:
Divide the number of moles of CoCl2 left by the number of moles of water lost. This will give us the mole ratio of CoCl2 to water:
Mole ratio of CoCl2 to water = (Number of moles of CoCl2 left) / (Number of moles of water lost)
6. Convert the mole ratio into whole numbers:
The mole ratio obtained in step 5 represents the simplest whole number ratio of CoCl2 to water molecules. Multiply the ratio by the same number to get whole numbers:
Mole ratio of CoCl2 to water * n = Whole number ratio of CoCl2 to water
Here, 'n' is a whole number that will ensure whole numbers in the ratio.
Using these steps, you can find the formula of the original hydrate.
CoCl2 = 0.88 g
H2O = 1.62-0.88 = 0.74 g
Convert to moles.
moles CoCl2 = 0.88/molar mass
moles H2O = 0.74/molar mass.
Now find the ratio of moles H2O to one(1) mole CoCl2. The easy way to do that is to divide moles CoCl2 by itself, then divide the moles H2O by the same small number and round to a whole number.