Question

lab math about micropipetting

Pipette Calibration Check Use this link below to view short video that demonstrates pipette calibration check. https://www.youtube.com/watch?v=1zYxCsKgs80 Lab Math Review 1. Calculate the Mean delivered volume of the P200 pipette being checked using the values(L): 150, 151, 151, 150 and 152. So.8 2. Dilute a 100X (100 times concentrated) stock solution with D-H2O to make 5L of a 1X solution. What volume of stock and D-H20 are needed? 3. A solution contains 10g of solute dissolved with 0.8 L of water. What is the % w/v of this solution? 4. A 3.5% w/v solution contains how many mg of solute in 500 mL of solution? 5. Make 500mL of a 5mM HCL solution from a 10M HCL stock solution. What volume of stock and D-H2O are needed? 6. You need 50 ng of DNA in 5 HL to set up a PCR reaction. What is the concentration of DNA needed for the reaction? Dilute the 350ng/L stock DNA specimen to use in the reaction. Show your work. Do more with Microsoft Edge - the fast, new browser built for Windows 10. Change my default Don't ask again 12:24 AM

Answer 1

1. Mean : x̄. The Volume mean is:

         ( 150 + 151 + 151 + 150 + 152 ) /5 = 150.8 uL

2.    100X to 1X by dilution using d-H₂O :

      Total volume : 5 L

       volume stock needed : 1X / 100X * 5L = 0.05 L or 50 mL

       Volume of d-H₂O : 4.95 L

3.   10 g of solute dissolved in 0.8 L or 800 mL of water :

we take Volume of solution ~ 800 mL

      % w/v   = ( g/ mL * 100) = 10 g / 800 mL * 100 = 1.25 %

4.

3.5 w/v % solution :

% w/v   = ( g/ mL * 100)

500 mL solution contains : 0.035 * 500 = 17.5 g

since, 1g = 1000 mg

thus, amount of solute : 17500 mg

5.

stock solution : 10 M HCl

we need : 500 ml of 5 mM HCl .

thus moles of HCl needed : 5*10^-3 mol/L * 0.5 L = 2.5*10^-3 mol

volume of stock solution needed :   2.5*10^-3 mol / 10 mol/L   = 2.5*10^-4 L = 0.25 mL

Volume of d-H₂O : 499.75 mL

6.

50 ng DNA in 5uL :

Thus conc. of this solution : 50 ng/ 5 uL = 50*10^-9 g / 5*10^-6 L = 0.01 g/L or 10 ng/uL

Original stock solution 350 ng/ul : 35 time dilution.