describe a prepare a 0.25 L.0.5 mol standart solution of NaoH
How many mols do you need? That's M x L = 0.5M x 0.25L = 0.125 mols.
Convert mols to grams. g = mols x molar mass.
To prepare a 0.25 L, 0.5 mol standard solution of NaOH, you will need to follow these steps:
Step 1: Determine the molecular weight of NaOH.
The molecular weight of NaOH is calculated as follows:
Na (Sodium) = 22.990 g/mol
O (Oxygen) = 16.00 g/mol
H (Hydrogen) = 1.008 g/mol
So, NaOH (Sodium Hydroxide) = Na + O + H = 22.990 + 16.00 + 1.008 = 39.998 g/mol ≈ 40.00 g/mol.
Step 2: Calculate the grams of NaOH required.
The number of moles (mol) of NaOH can be found by multiplying the volume (L) of the solution by the desired molarity (mol/L). In this case, the desired molarity is 0.5 mol and the desired volume is 0.25 L.
Moles of NaOH = Molarity (mol/L) × Volume (L) = 0.5 mol/L × 0.25 L = 0.125 mol.
To find the grams of NaOH needed, multiply the moles of NaOH by the molecular weight:
Grams of NaOH = Moles of NaOH × Molecular weight of NaOH = 0.125 mol × 40.00 g/mol = 5.00 g.
Step 3: Dissolve NaOH in water.
Take the calculated amount of NaOH (5.00 g) and add it gradually to a beaker containing some distilled water. Stir the mixture gently until all the NaOH has dissolved in the water. Be cautious as NaOH is caustic and can irritate the skin and eyes.
Step 4: Dilute to the desired volume.
Transfer the NaOH solution into a volumetric flask (make sure the beaker is clean and dry). Rinse the beaker with distilled water and transfer the rinsing to the volumetric flask to ensure you have the full volume of 0.25 L. Add more distilled water to the flask until the solution reaches the 0.25 L mark.
Step 5: Mix well.
Close the volumetric flask with a stopper or a lid and mix the solution well by gently inverting it a few times to ensure the homogeneity of the solution.
Congratulations! You have now prepared a 0.25 L, 0.5 mol standard solution of NaOH. Remember to label it properly to indicate the concentration and contents.