How would you go about making 250ml of a 20X stock solution of NaCl to dilute later to a final concentration of 50mM? I know that the molecular weight of NaCl is 58.44 but I am not sure where to start. I need to figure out the amount of NaCl and water needed. Thank you!
14.61 g of NaCl
To make a 20X stock solution of NaCl that can be diluted later to a final concentration of 50mM, you will need to follow these steps:
Step 1: Calculate the grams of NaCl required to make a 1X solution.
To make a 1X solution, you need a final concentration of 50mM, which is equivalent to 50 millimoles per liter (50 mM = 50 mmol/L). The molecular weight of NaCl is 58.44 g/mol. So, to calculate the grams of NaCl required for a 1X solution, use the following formula:
Grams of NaCl = moles of NaCl x molecular weight of NaCl
Grams of NaCl = 50 mmol/L x 58.44 g/mol
Step 2: Calculate the amount of NaCl required for the 20X stock solution.
Since you want to make a 20X stock solution, multiply the grams of NaCl required for a 1X solution by 20.
Grams of NaCl for a 20X solution = 20 x (Grams of NaCl for a 1X solution)
Step 3: Calculate the volume of the 20X stock solution.
To calculate the volume of the 20X stock solution, divide the desired final volume of the stock solution (250 ml) by the desired final concentration (20X). Use the following formula:
Volume of 20X stock solution (ml) = Desired final volume (ml) / Desired final concentration (X)
Volume of 20X stock solution = 250 ml / 20
Step 4: Calculate the volume of water needed to make the 20X stock solution.
To make the 20X stock solution, subtract the volume of NaCl from the total desired volume of the stock solution:
Volume of water needed (ml) = Volume of 20X stock solution - Volume of NaCl
Step 5: Measure the calculated grams of NaCl and add it to the calculated volume of water to prepare the 20X stock solution.
By following these steps, you will be able to make a 250 ml 20X stock solution of NaCl to dilute later to a final concentration of 50 mM.
To make a 250ml 20X stock solution of NaCl, you need to calculate the amount of NaCl and water needed. Here's the step-by-step process:
Step 1: Calculate the number of moles needed for the desired concentration.
Concentration of the final solution = 50mM (millimolar)
Volume of the final solution = 250ml
Concentration (in moles) = (Concentration (in mM) * Volume (in ml)) / 1000
So, the number of moles needed = (50mM * 250ml) / 1000 = 12.5 mmol
Step 2: Calculate the mass of NaCl needed.
To convert moles to grams, you need to use the molecular weight of NaCl, which is 58.44 g/mol.
Mass of NaCl needed (in grams) = Number of moles * Molecular weight of NaCl
= 12.5 mmol * 58.44 g/mol
= 730.5 grams
Therefore, you need 730.5 grams of NaCl to make the 20X stock solution.
Step 3: Calculate the volume of water needed.
To make a 250ml solution, you need to subtract the volume of NaCl from the total volume.
Volume of water needed = Total volume - Volume of NaCl
= 250ml - 250ml/20
= 250ml - 12.5ml
= 237.5ml
So, you need 237.5ml of water to make the 20X stock solution.
In summary, to make a 250 ml 20X stock solution of NaCl, you would need 730.5 grams of NaCl and 237.5 ml of water.