if you heat 15.00g of the hydrate CaSO4*2H20, and drive off the water, what is the weight of the anhydrous salt remaining?
How do I go about solving this?
Just make it a regular stoichiometry problem.
CaSO4*2H2O ==> CaSO4 + 2H2O
so then would i find the gfm of the CaSO4?
and get 136.2 as my answer?
Do you really believe you can start with 15.00 g CaSO4.2H2O, lose the water, and end up with more than 15.00 g? Not likely. It MUST be less than 15.00 grams CaSO4.
CaSO4.2H2O ==> CaSO4 + 2H2O
moles CaSO4.2H2O = 15.00 g x (1 mole CaSO4.2H2O/172.172) = 0.08712 moles.
moles CaSO4 = same.
grams CaSO4 = moles CaSO4 x molar mass CaSO4 = ??
Well, it seems like you've got yourself a little chemistry conundrum! Let's break it down.
First, we need to find the weight of the water in the hydrate. CaSO4·2H2O tells us that there are two water molecules attached to one salt molecule.
The molar mass of water (H2O) is approximately 18 g/mol, so the molar mass of two water molecules (2H2O) is about 36 g/mol.
Since you have 15.00g of the hydrate, we divide that by the molar mass of two water molecules to find the number of moles of water: 15.00g / 36 g/mol ≈ 0.417 mol of water.
Next, we determine the molar mass of CaSO4. The atomic masses are approximately: Ca (40 g/mol), S (32 g/mol), and O (16 g/mol).
Therefore, the molar mass of CaSO4 is 40 + 32 + (4 × 16) g/mol = 136 g/mol.
The molar mass of the hydrate (CaSO4·2H2O) is then the sum of the molar masses of CaSO4 plus two water molecules: 136 g/mol + (2 × 18 g/mol) = 172 g/mol.
Now, to find the weight of the anhydrous salt, we multiply the moles of water (0.417 mol) by the molar mass of the hydrate (172 g/mol): 0.417 mol × 172 g/mol ≈ 71.224 g.
Therefore, the weight of the anhydrous salt remaining is approximately 71.224 grams.
But hey, don't go drying out on me! Stay hydrated, my friend!
To solve this problem, you need to understand the concept of hydrates and their properties. A hydrate is a compound that contains a specific number of water molecules chemically bound to its structure. In this case, the hydrate is CaSO4*2H2O, which means it contains two water molecules for every molecule of CaSO4.
To find the weight of the anhydrous (without water) salt remaining, you need to determine the weight of the water that is driven off and subtract it from the original weight of the hydrate.
Step 1: Calculate the molar mass of CaSO4*2H2O.
- The molar mass of one molecule of CaSO4 is the sum of the atomic masses of calcium (Ca), sulfur (S), and four oxygen (O) atoms. You can find these atomic masses from the periodic table.
- The molar mass of two water molecules (2H2O) is the sum of the atomic masses of two hydrogen (H) atoms and one oxygen (O) atom, multiplied by two.
Step 2: Find the number of moles of the hydrate.
- Divide the given mass of the hydrate (15.00g) by the molar mass calculated in Step 1.
Step 3: Calculate the number of moles of water.
- Since there are two water molecules for every molecule of CaSO4, multiply the number of moles of hydrate by 2.
Step 4: Find the mass of water.
- Multiply the number of moles of water calculated in Step 3 by the molar mass of water.
Step 5: Calculate the mass of the anhydrous salt.
- Subtract the mass of water calculated in Step 4 from the given mass of the hydrate.
By following these steps, you should be able to find the weight of the anhydrous salt remaining after driving off the water.