An experiment in your laboratory requires exactly 500mL of 0.0200M solution of Na2CO3. You are given solid Na2CO3, distilled water and a 500mL volumetric flask. describe how you would prepare the required solution.
You want how many moles? M x L = mols = 0.0200 x 0.500 = 0.01 mols.
Then grams = mols Na2CO3 x molar mass Na2CO3 = ?
Weigh out exactly that many grams Na2CO3, transfer quantitatively to a 500 mL volumetric flask, add some distilled water, swirl until all of the solid is dissolved, add more distilled water to the mark on the flask, stopper, mix thoroughly, label.
To prepare a 500mL solution of 0.0200M Na2CO3, follow these steps:
1. Calculate the number of moles of Na2CO3 needed:
- Molarity (M) = 0.0200M
- Volume (V) = 0.500L
- Moles = Molarity × Volume
- Moles = 0.0200M × 0.500L = 0.0100 moles
2. Determine the molar mass of Na2CO3:
- Sodium (Na) atomic mass = 22.99 g/mol
- Carbon (C) atomic mass = 12.01 g/mol
- Oxygen (O) atomic mass = 16.00 g/mol
- Na2CO3 molar mass = 2 × Na atomic mass + C atomic mass + 3 × O atomic mass
= 2 × 22.99 g/mol + 12.01 g/mol + 3 × 16.00 g/mol
= 105.99 g/mol
3. Calculate the mass of Na2CO3 needed:
- Mass = Moles × Molar mass
- Mass = 0.0100 moles × 105.99 g/mol
- Mass = 1.0599 grams (rounding to four decimal places)
4. Weigh out the required mass of Na2CO3:
- Using a balance, measure out 1.0599 grams of solid Na2CO3.
5. Transfer the solid Na2CO3 to the 500mL volumetric flask:
- Add the solid Na2CO3 to the flask while ensuring none of it is spilled.
6. Fill the volumetric flask with distilled water:
- Use a water source, preferably distilled water, to fill the flask to the mark on the neck of the volumetric flask.
- Ensure that the bottom of the meniscus is exactly on the mark to reach a total volume of 500mL.
7. Mix thoroughly:
- Place a stopper on the flask and gently invert it a few times to mix the solid Na2CO3 and water completely.
Now, you have successfully prepared a 500mL solution of 0.0200M Na2CO3 in your laboratory.
To prepare the required solution of 0.0200M Na2CO3 using solid Na2CO3, distilled water, and a 500mL volumetric flask, here are the steps:
1. Calculate the amount of Na2CO3 needed:
- Molarity (M) = moles of solute / volume of solution (in L)
- Rearranging the equation: moles of solute = Molarity x volume of solution (in L)
- In this case, the desired molarity is 0.0200M, and the desired volume is 500mL (0.500L) of solution.
- Moles of solute = 0.0200M x 0.500L = 0.0100 moles of Na2CO3
2. Weigh out the solid Na2CO3:
- The molar mass of Na2CO3 is approximately 105.99 g/mol.
- Calculate the mass of Na2CO3 needed using the molar mass and the moles calculated in step 1:
- Mass of Na2CO3 = moles x molar mass = 0.0100 moles x 105.99 g/mol = 1.06 grams of Na2CO3.
3. Dissolve the solid Na2CO3 in distilled water:
- Add the 1.06 grams of solid Na2CO3 into a clean beaker.
- Add a small amount of distilled water to dissolve the solid. Stir the solution to ensure complete dissolution.
4. Transfer the solution to the 500mL volumetric flask:
- Once the solid is completely dissolved, transfer the solution to the 500mL volumetric flask using a funnel or pipette.
- Rinse the beaker with distilled water to ensure all of the solution is transferred.
5. Fill the volumetric flask to the mark:
- Using a dropper or a pipette, carefully add distilled water to the volumetric flask until the solution reaches the mark on the neck of the flask.
- To ensure accuracy, add the water drop by drop near the end, and use a stirring rod to mix gently.
6. Mix thoroughly:
- After filling the solution to the mark, insert a stopper or cap on the volumetric flask and mix the solution thoroughly by inverting it several times.
Congratulations! You have successfully prepared a 500mL, 0.0200M Na2CO3 solution using solid Na2CO3, distilled water, and a 500mL volumetric flask.