For each of the problems, write the answer in the underlined space. SHOW your wo

Question

For each of the problems, write the answer in the underlined space.  SHOW your work in the space provided.  MATH COUNTS. UNITS COUNT.

1. 20 gal = L

2. 18 g/L=   mg/mL

3. 10 mm= km

4. 6000 nm=   meters

5. 4 lbs= g

Solve the following :

6. You have 1 billion atoms of hydrogen in your hand. How many moles do you have?

7. The temperature outside is 62oF  What was the reading in Celsius?

8. If 1mL of water weighs 1 gram, how many kg does 1 gal of water weigh?

9. Write the following terms in correct SI units.  (Convert to the standard to correct unit.  Then write it in correct form)

a. 300 grams per deciliter

b. 0.002 (microliters/centimeter)/kilosecond

c. 16 milliampere×second per volt

10. If you get 9 kcal of energy per gram of sugar, then how many ergs of energy did you receive from a 10 gram serving of rock candy (pure sugar).  

11. Albumin (MW = 65000) has a normal concentration in plasma of 5 g per 100 mL.  What is its molar concentration?

12. A balanced saline solution (isoosmotic with your blood cells) contains 0.85% NaCl (MW = 60).  What is the molarity of this solution?

13. How many grams of glucose (C6H12O6) must I weigh out to make 0.5 L of a 0.4 M solution?

14. How may mL of a 100 mM solution of glucose are needed to provide 150 mmole of glucose.

15. How many grams of NaHCO3 must you weigh out to make 250 mL of a 0.2 M solution?

16. How many grams of sucrose are needed to make up 500 mL of a 10% wt/vol solution?

17. I weighed out 0.0036 g of estradiol  (M.W. 272.4 g/mol) in a dry vial.  How much ethanol must I dissolve the steroid in to yield a 10 mM solution?

18. I have a 10 M stock solution of LiCl and I need 0.4 L of 1.5 M LiCl for next week’s experiment.  How much stock must I use to make this working solution?

19. A stock solution of Bradford Protein assay reagent contains 0.5 mg /mL or the reactive dye called Brilliant Blue G-250.  To use the stock, you must first dilute it five-fold, i.e., 1/5X.  What is the concentration of dye in the diluted working solution?

20. I need 75 mL of  a 1:4 dilution of Reagent X.  How much  Reagent X do I need to make this? (n.b.  1:4 means 1 part stock + 4 parts diluent = 5 parts total.  This can also be written 1/5X dilution or a 5-fold dilution.)

21 Calculate the volume of 25% w/v NaCl needed to make 75 mL of a 0.3% wt/vol solution.

22. I need 1 L of a 5% solution of formaldehyde, but I onLy have a 37% solution.  How would I make the appropriate amount?

23. Calculate the volume of a 10 mM sucrose solution needed to make 125 mL of a 0.75 mM solution.

24. I have 25 mL of 0.4 M KCl, but I need to make 300 mL of  50 mM KCl?   Can I use the more concentrated stock to make the solution or do I need to weigh out more KCl ?   SHOW your calculations that allow you to say yes or no.

25. Take 9 mL of 9% w/v NaCl and dilute it to a total volume of 90 mL.  Write this dilution using 1/X nomenclature ; and 1:X nomenclature.

26. Define solution.  Careful: It must be exactly stated to distinguish from a mixture

27. What is the osmolarity of a 0.154 M NaCl solution (assuming complete dissolution)?

28. What is the normality of a 0.5 M HCl solution (assuming complete dissociation)?

29. What is the normality of a 2.0 M H3PO4 solution (assuming complete dissociation)?

30. How many chloride ions are in 1 mL of the 0.5 M HCl solution above (assuming complete dissociation) ?

31. What is the concentration of H+ in a solution of HCl with pH 3.5?

32. If you diluted a solution of pH 3.5 by a 10-fold, what would be the predicted pH?

33. You have added several drops of 1N HCL to a solution, increasing its [H+] from 5.33 x 10 -4M to 8.8 x 10-4M.  What are the starting and ending pH of this solution?

Start End

34. You have added HCl to 0.2 L of unbuffered salt solution, changing its pH from 6.5 to 5.9.  How many mL of 0.01 N HCl must you add to achieve this change?

35. What is the [OH-] concentration in an unbuffered salt solution of pH 9.3?

38. What is the [H+] of a solution that was created by diluting a pH 5.9 solution 10,000- fold (1/10000X)? (HINT: what is the diluent?)

Explanation / Answer

1.
1 gal = 3.78 L
so,
20gal= 20*3.78 = 75.6 L

2.
18 g/L
= 18 mg/mL

3.
10 mm = 10*10^-3 m
= 10*10^-6 km
= 1*10^-5 km

4.
1 lbs = 453.6 g
so,
4lbs = 4*453.6 g
= 1814.4 g

I am allowed to answer only 1 question at a time

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