How would 250 ml of 0.15 M KNO3 solution be prepared
To prepare 250 ml of 0.15 M KNO3 solution, you will need the following steps:
1. Calculate the amount of KNO3 needed: Concentration (M) = moles/Liter, therefore moles = concentration × volume (L). In this case, moles = 0.15 M × 0.250 L = 0.0375 moles.
2. Determine the molar mass of KNO3: KNO3 consists of potassium (K), nitrogen (N), and oxygen (O). The molar masses are K = 39.10 g/mol, N = 14.01 g/mol, and O = 16.00 g/mol. Adding these up gives us the molar mass of KNO3 = 39.10 + 14.01 + (3 × 16.00) = 101.11 g/mol.
3. Calculate the grams of KNO3 needed: Use the formula grams = moles × molar mass. So, grams = 0.0375 moles × 101.11 g/mol = 3.788 g.
4. Weigh out 3.788 grams of KNO3 using a balance.
5. Add the weighed KNO3 to a container.
6. Add distilled water to the container until the final volume is 250 ml. Use a graduated cylinder or a volumetric flask to measure the correct volume of water.
7. Stir or shake the container thoroughly to ensure the KNO3 dissolves completely in the water.
8. The resulting solution will be 250 ml of 0.15 M KNO3.
To prepare 250 ml of a 0.15 M KNO3 solution, you would need to follow these steps:
1. Determine the molar mass of KNO3 (potassium nitrate).
- The molar mass of K (potassium) is approximately 39.1 g/mol.
- The molar mass of N (nitrogen) is approximately 14.0 g/mol.
- The molar mass of O (oxygen) is approximately 16.0 g/mol.
- Since KNO3 consists of one potassium atom (K), one nitrogen atom (N), and three oxygen atoms (O), the total molar mass of KNO3 is:
Molar mass of KNO3 = (39.1 g/mol) + (14.0 g/mol) + 3 * (16.0 g/mol)
2. Calculate the number of moles of KNO3 that you need to make a 0.15 M solution.
- Molarity (M) is defined as moles of solute divided by volume of solvent (in liters). Therefore, we can rearrange the equation to solve for moles:
Moles of solute = Molarity * Volume of solvent (in liters)
- Convert the volume of solvent from milliliters (ml) to liters (L). In this case, 250 ml is equivalent to 0.25 L.
- Plug in the known values:
Moles of KNO3 = 0.15 M * 0.25 L
3. Convert moles to grams.
- Multiply the moles of KNO3 by the molar mass of KNO3 that you calculated in step 1 to get the mass of KNO3 required.
- The formula for calculating mass is:
Mass = Moles * Molar mass
4. Dissolve the calculated mass of KNO3 in enough water to make a final volume of 250 ml.
- Weigh out the calculated mass of KNO3 using an analytical balance.
- Transfer the weighed KNO3 into a clean and empty 250 ml volumetric flask.
- Add water to the flask, slowly and carefully, until the volume reaches the 250 ml mark on the flask. Make sure the KNO3 is completely dissolved in the water.
After following these steps, you will have prepared 250 ml of a 0.15 M KNO3 solution.
You want how many moles? That's M x L = 0.15 x 0.250 = ? moles KNO3.
Then grams = mols KNO3 x molar mass KNO3 = ? grams.