Describe how you would prepare 950 mL of a 1X CuSO4. 5H2O from a 25X CuSO4. 5H2O
ID: 133925 • Letter: D
Question
Describe how you would prepare 950 mL of a 1X CuSO4. 5H2O from a 25X CuSO4. 5H2O stock.
If you were presented with 2L of a 2 M sucrose stock solution, many grams of sugar would be in a 100 mL aliquot.
How many grams of calcium chloride ( ) would you dissolve in water to make a 0.2 M CaCl2 solution with a final volume of 400mL final volume.
How many grams of calcium chloride would you dissolve in water to make a total 0.4 M CaCl2 solution with a 1 L final volume.
How many grams of sucrose would you dissolve in water to make a .3mM sucrose solution with 100 mL final volume?
3. Describe how you would prepare 500 ml of a 10% BHI (Brain Heart Infusion) growth media and 15% agar made together? Making Solutions of Differing Molarity Concentrations 1. Describe how you would prepare 125 mL of a 10 M NaOH solution.
Explanation / Answer
50 mL of a 5 mM NaCl solution from a 1 M NaCl stock:
Using formula M1V1 = M2V2 where M1 and M2 are concentrations of two solution with volumes V1 and V2 respectively.
(1000 mM) x V1 = (5 mM) x 50 mL
V1 = (250/1000) mL = 0.250 mL or 250 uL.
Add 250 microlitres of 1 M stock to a volumetric flask and make up the volume to 50 mL.
950 mL of a 1X CuSO4. 5H2O from a 25X CuSO4. 5H2O stock:
For this, we have to add 1 part from stock solution while 24 part from solvent (water) used for preparing stock solution.
Divide total volume required (950 mL) by concentration of stock (25) and multiply by desired concentration (1), we get (950x1)/25 mL = 38 mL.
Add 38 mL of stock solution to a measuring cylinder and make up the volume upto 950 mL.
For 2 M sucrose, calculating the amount of solute:
2 M solution of sucrose will contains a total no. of moles = 2 mol per 1000 mL.
Therefore, no. of moles in 100 mL will be (2x100)/1000 = 0.2 mol.
Also, Molecular weight of sucrose = 342.2965 g/mol.
No. of moles = (amount in grams)/(molecular weight)
or 0.2 mol = w/(342.2965 g/mol)
or w = 68.4593 g
68.4593 grams of sucrose will be there in 100 mL of 2M sucrose solution.
For preparing 400 mL of 0.2 M CaCl2 solution:
Using formula:
Molarity = (weight in grams/molecular weight)/(volume in litre)
0.2 = (w/110.98)/0.4
or w = 8.878 g
Dissolve 8.878 grams of calcium chloride in water and make up the volume to 400 mL.
For preparing 1 L of 0.4 M CaCl2 solution:
Similar to the previous solution, we get
0.4 = (w/110.98)/1
or w = 44.392 g
Dossolve 44.392 grams of CaCl2 in water and make up the volume to 1 litre.
Prepare 100 mL of 0.3 mM sucrose solution:
Similar to previous solution, we get for sucrose
0.3/1000 = (w/342.2965)/0.1
or w = 0.01027 g.
Dissolve 0.01027 grams of sucrose in water and make up the volume to 100 mL.