Chemistry 317 Biochemistry
Standard Calculations Practice.
Assignment 1
 Please present the answers in the appropriate format or you will lose credit.   All terms must be explicit and expressed in appropriate units.  If you are asked to make a solutioin state all steps in making the solution. 

1.a) If there are 8.0 mg of Na+ contaminant per liter of water sample, calculate the number of moles of Na+ per liter.
b)calculate the weight of Na+ in another sample of water that contains 100 µmol Na+/L.

2. If there are 8.0 mg of dissolved oxygen per liter of water at 200C an 1 atm, calculate the number of moles of molecular oxygen and the molarity of dissolved molecular oxygen per liter of water.

3. Calculate the number of molecules of ampicillin per microliter of a 10.0 nM solution.

4. For 6.7 g of sodium acetate and 6.7 g of magnesium acetate, calculate a) the moles of each salt and b) the moles of acetate ion in the sodium acetate and in the magnesium acetate.

5. If 6.7 g of sodium acetate or 6.7 g of magnesium acetate is dissolved in a total volume of 0.200 L of water calculate
a) the molarity of sodium acetate
b) the molarity of magnesium acetate
c) the molarity of acetate ion in each solution

6. How many grams of EDTA tetrahydrate are needed to prepare 0.100 L of a 0.020 M solution?

7. How would you prepare 0.100 L of a 0.020 M solution of acetate ion using sodium acetate? Using magnesium acetate?

8. The concentration of ampicillin in a stock solution is 5.00 x 103 µg/mL. (Ampicillin fw 349.41 g/mol) Calculate:
a) µg of ampicillin in 0.100 ml of the solution
b) µmol of ampicillin in 0.100 ml of the solution
c) molarity of ampicillin
d) how to prepare 30.0 mL of a working solution with a concentration of 10.0 µg/ml

9. Describe what is needed to prepare 0.200 L of a 100 µM solution. (FW, anhydrous ATP 487.2 g/mol) The ATP powder available in the laboratory is a trihydrate and has 2 moles of sodium ion per mole of ATP Please calculate the preparaton both ways).

10. Beta mercaptoethanol is available as a 98%(w/w) solution (sp gr 1.114 g/ml) describe the prepartion of 0.100 L of a 50mM solution? (FW 78.13)

11. The concentration of sodium ion in a standard solution is 1000 ppm (w/v). What is the molarity of Na+?

12. Prepare 100.0 ml of 2.0 M solution of acid and base
a) 6 N stock solutions of  H2SO4 and of  NaOH
b) Concentrated HCl and NaOH solid.

13. A 75.0 µL aliquot of a solution of EcoR1 (100 units/mL) is added to 0.50 ml of buffer. Calculate
a) the dilution factor and
b) the final concentration of EcoRI in the buffer
c) prepare 1.5 ml of 15.0 units/ml solution starting with the 100.0 units/ml stock