what will be the mass of angydrous Alum left over if one starts with 100.00 g of hydrated Alum?
100 g KAl(SO4)2.12H2O
What percent H2O is in the molecule? Then fraction x 100 g = g anhydrous material after water is driven out.
To determine the mass of anhydrous alum left over when starting with 100.00 g of hydrated alum, follow these steps:
1. Determine the molecular formula of the hydrate. Alum is commonly known as potassium aluminum sulfate, with the chemical formula KAl(SO4)2·12H2O. This means that for every mole of hydrated alum, there are 12 moles of water molecules associated with it.
2. Calculate the molar mass of the hydrated alum. The molar mass of KAl(SO4)2·12H2O is the sum of the molar masses of its constituent atoms:
- Atomic mass of K (potassium) = 39.10 g/mol
- Atomic mass of Al (aluminum) = 26.98 g/mol
- Atomic mass of S (sulfur) = 32.06 g/mol
- Atomic mass of O (oxygen) = 16.00 g/mol
- Atomic mass of H (hydrogen) = 1.01 g/mol
Thus, the molar mass of KAl(SO4)2·12H2O is:
(39.10 g/mol) + (26.98 g/mol) + 2*(32.06 g/mol) + 24*(1.01 g/mol) + 12*(16.00 g/mol) = 474.39 g/mol
3. Calculate the number of moles of hydrated alum. Use the given mass of 100.00 g and divide it by the molar mass calculated in step 2:
Moles of hydrated alum = 100.00 g / 474.39 g/mol
4. Calculate the number of moles of anhydrous alum. Since each mole of hydrated alum contains 12 moles of water, subtract 12 times the moles of hydrated alum from the moles of hydrated alum calculated in step 3:
Moles of anhydrous alum = Moles of hydrated alum - (12 * Moles of hydrated alum)
5. Determine the mass of anhydrous alum. Multiply the moles of anhydrous alum by its molar mass to get the mass:
Mass of anhydrous alum = Moles of anhydrous alum * Molar mass of anhydrous alum
By following these steps, you will be able to calculate the mass of anhydrous alum left over when starting with 100.00 g of hydrated alum.