How many grams of K2Cr2O7 (Potassium dichromate) must be used to make 250 ml of a0.125 M solution?
How many mols do you need? That's mols K2Cr2O7 = M x L = ?
Then mols = g/molar mass. You know mols ad molar mass. solve for grams.
0.10622g
To calculate the grams of K2Cr2O7 required to make a 0.125 M solution in 250 ml of solution, we need to use the formula:
grams = (Molarity * Volume * Molar mass) / 1000
First, let's calculate the molar mass of K2Cr2O7:
K2Cr2O7:
Potassium (K) = 39.1 g/mol
Chromium (Cr) = 52 g/mol
Oxygen (O) = 16 g/mol
Molar mass of K2Cr2O7 = (2 * 39.1) + (2 * 52) + (7 * 16)
Molar mass of K2Cr2O7 = 294.2 g/mol
Now, substitute the values into the formula:
grams = (0.125 * 250 * 294.2) / 1000
grams = (0.125 * 250 * 294.2) / 1000
grams = 9.21375 g
Therefore, approximately 9.21 grams of K2Cr2O7 should be used to make a 0.125 M solution in 250 ml of solution.
To calculate the number of grams of K2Cr2O7 needed to make a 0.125 M solution, you need to know the molar mass of K2Cr2O7 and the volume of the solution you want to prepare. Here are the steps to find the answer:
Step 1: Determine the molar mass of K2Cr2O7.
The molar mass of K2Cr2O7 can be calculated by adding up the atomic masses of each element in the compound:
Potassium (K) = 39.10 g/mol (2 atoms)
Chromium (Cr) = 52.00 g/mol (2 atoms)
Oxygen (O) = 16.00 g/mol (7 atoms)
So, the molar mass of K2Cr2O7 = (2 * 39.10) + (2 * 52.00) + (7 * 16.00) = 294.18 g/mol.
Step 2: Use the formula: Moles = Molarity * Volume (in liters).
Since the given volume is in milliliters, we need to convert it to liters.
250 mL = 250/1000 = 0.25 L.
Now we can calculate the moles of K2Cr2O7:
Moles = 0.125 M * 0.25 L = 0.03125 moles.
Step 3: Convert moles to grams.
To convert moles to grams, multiply the number of moles by the molar mass of the compound:
Grams = Moles * Molar mass.
Grams = 0.03125 moles * 294.18 g/mol ≈ 9.19 grams.
Therefore, approximately 9.19 grams of K2Cr2O7 is required to make 250 ml of a 0.125 M solution.