Online chemistry lab preparing standards help?
I was told to prepare some standard for a chemistry lab and here where the instructions:
Obtain a solution of known phosphate concentration. In this lab we will use (1.e-002M) potassium dihydrogen phosphate, KH2PO4. Note the concentration on your data sheet.
Pipet 0.50mL of the standard phosphate solution into a 100mL volumetric flask. Using a graduated cylinder, add 10.0mL of the ammonium molybdate solution to the flask. Then dilute to the mark with distilled water. Make sure you label this volumetric with the concentration of phosphate. (McVc=MdVd) Do this by choosing label from the menu (or right clicking)
Where
Mc = concentration of the original standard phosphate solution.
Vc = volume of concentrated standard phosphate solution TRANSFERRED to the volumetric.
Md = new diluted concentration.
Vd = total volume of the diluted solution.
The Part I do not understand is filling in the McVc=MdVd.
Here are my guesses on some but I am not 100% sure and could use some help:
Mc
Vc
Md=.5ml
Vd=100ml
0.50 mLs of KH2PO4 was diluted to 100 mLs in the volumetric flask.
The concentration of the diluted KH2PO4 in the 100.00 mL volumetric flask is:
(0.50mLs /100mLs)(Original concentration of KH2PO4). Not sure where the decimal point is in the original phosphate concentration.
I share GK's dilemma about the original concentration. What is 1.e-002M?
Your question is about McVc = MdVd.
Mc = molarity of the standard solution. That is the 1.e-002M whatever that is.
Vc is the 0.50 mL. Md is the new molarity and is what you are to calculate. Vd is the 100 mL. So the set up looks like this (and you will need to change the concn to whatever 1.e-002 M means.
1.e-002M*0.50 = Md*100.
Solve for Md.
To fill in the equation McVc=MdVd, you need to determine the values for each variable.
1. Mc: Mc represents the concentration of the original standard phosphate solution. In this case, the given concentration is (1.e-002M) potassium dihydrogen phosphate, KH2PO4. Therefore, Mc = 1.e-002 M.
2. Vc: Vc represents the volume of the concentrated standard phosphate solution transferred to the volumetric flask. According to the instructions, you need to pipet 0.50 mL of the standard phosphate solution into a 100 mL volumetric flask. Hence, Vc = 0.50 mL.
3. Md: Md represents the new diluted concentration. Since you are diluting the standard phosphate solution, the new concentration needs to be calculated. In this case, the diluted concentration will be the concentration of the original solution after dilution. So, Md will be the concentration you calculate using the dilution formula.
4. Vd: Vd represents the total volume of the diluted solution. In this case, you are adding the concentrated standard phosphate solution (Vc = 0.50 mL) to a 100 mL volumetric flask, and then diluting it with distilled water. Therefore, Vd will be the final volume of the solution in the volumetric flask, which is 100 mL.
To calculate Md, you can use the dilution formula:
McVc = MdVd
Using the values we found earlier:
(1.e-002 M)(0.50 mL) = Md(100 mL)
Solving for Md:
Md = (1.e-002 M)(0.50 mL) / (100 mL)
Simplifying the equation:
Md = 0.00005 M
Therefore, the new diluted concentration (Md) is 0.00005 M.