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Unformatted text preview: PHCY 6106 PRACTICE PROBLEMS 2010 Dilution and Concentration 1. In preparing a solution for a wet dressing, two 0.3g tablets of potassium permanganate are
dissolved in 1 gallon of purified water. What will be the percentage strength (w/v) of the
solution? 0.0159% = 0.016%
2. What is the strength of a sodium chloride solution obtained by evaporating 800g of a 10%
(w/w) solution to 250g? 32%
3. If two tablespoonfuls of povidone iodine solution (10% w/v) are diluted to 1 quart with
purified water, what is the ratio strength of the dilution? 1:315
4. How many milliliters of water must be added to 250mL of a 25% (w/v) stock solution of
sodium chloride to prepare a 0.9% (w/v) sodium chloride solution? 6694.4 mL
5. A certain product contains benzalkonium chloride in a concentration of 1:5000 (w/v). How
many milliliters of a 17% solution of benzalkonium chloride should be used in preparing 4
liters of the product? 4.7mL
6. How many milliliters of water for injection must be added to 10 liters of a 50% (w/v)
dextrose injection to reduce the concentration to 30% (w/v)? 6667mL
7. How many milliliters of Burow’s Solution (containing 5% w/v of aluminum acetate) should
be used in preparing 2 liters of a 1:800 (w/v) solution to be used as a wet dressing? 50mL
8. If a pharmacist adds 3g of a hydrocortisone to 60g of a 5% (w/w) hydrocortisone cream,
what is the final percentage strength of hydrocortisone in the product? 9.52%
9. How many milliliters of a 1% (w/v) solution of phenylmercuric nitrate may be used in
preparing a 100mL prescription requiring 1:50,000 (w/v) of phenyl mercuric nitrate as a
preservative? 0.2mL
10. Lactic Acid
10% (w/v)
Salicylic Acid
10% (w/v)
Flexible Collodion qs
15mL
Sig. For war removal. Use externally as directed.
How many milliliters of an 85% (w/w) solution of lactic acid with a specific gravity of 1.21
should be used in preparing the prescription? 1.5mL
11. How many milliliters of water should be mixed with 1200g of 65% (w/w) alcohol to make
45% (w/w) alcohol? 533mL
12. How many milliliters of syrup containing 85% (w/v) of sucrose should be mixed with 150mL
of a syrup containing 60% of sucrose to make a syrup containing 80% (w/v) of sucrose?
600 mL
13. A pharmacist mixes 10mL of 38% (w/w) hydrochloric acid with enough purified water to
make 360mL. If the specific gravity of hydrochloric aci is 1.20, calculater the percentage
strength (w/v) of the resulting dilution. 1.267% or 1.3% Teixeira 1 PRACTICE PROBLEMS PHCY 6106 2010 Dilution and Concentration 14. In using isoproterenol hydrochloride solution (1:5000 w/v), 1mL of the solution is diluted to
10mL with sodium chloride injection before intravenous administration. What is the
percentage concentration of the diluted solution? 0.002%
15. Zinc Oxide
Calamine
Petrolatum
Sig. Apply. aa 2g
60g If the prescription was prepared as written, and then the prescriber wished to change the
concentration of zinc oxide to 10% (w/w), (a) how many additional grams of zinc oxide
should be added, and (b) how many grams of a 20% (w/w) zinc oxide ointment could be
added to change the strength to 10% (w/w) of zinc oxide? 4.89g, 44g
16. How many grams of zinc oxide should be added to 3400g of a 10% zinc oxide ointment to
prepare a product containing 15% of zinc oxide? 200g
17. How many grams of petrolatum (diluent) should be added to 250g of a 25% ichthammol
ointment to make a 5% ointment? 1000g
18. Zinc Oxide
Hydrophilic Petrolatum
Purified Water
Hydrophilic Ointment ad
Sig. Apply to affected area. 1.5
2.5
5.0
30.0 How much zinc oxide should be added to the product to make an ointment containing 10%
of zinc oxide? 1.667g
19. How many milligrams of sodium fluoride are needed to prepare 100mL of a sodium fluoride
stock solution such that a solution containing 1:500,000 (w/v) of sodium fluoride results
when 0.5mL is diluted to 250mL with water? 100mg
20. Four equal amounts of belladonna extract, containing 1.15%, 1.30%, 1.35%, and 1.20% of
alkaloids, respectively, were mixed. What was the percentage strength of the mixture?
1.25%
21. What is the percentage of alcohol in a mixture containing 1500mL of witch hazel (14%
alcohol), 2000mL of glycerin, and 5000mL of 50% alcohol? 31.9%
22. A pharmacist mixes 200g of 10% ichthammol ointment, 450g of 5% ichthammol ointment,
and 1000g of petrolatum (diluent). What is the percentage of ichthammol in the finished
product? 2.58% Teixeira 2 PHCY 6106 PRACTICE PROBLEMS 2010 Dilution and Concentration 23. A hospital pharmacist constitutes a vial containing 2g of piperacillin sodium to 10mL with
sterile water for injection. This solution is then diluted by adding it to 100mL of 5%
dextrose injection for administration by infusion. What is the concentration, in milligrams
per milliliter (mg/mL), of piperacillin sodium in the infusion solution? 18.18 mg/mL
24. Calculate the percentage of alcohol in a lotion containing 2 liters of witch hazel (14%
alcohol), 1 liter of alcohol (95%), and enough boric acid solution to make 5 liters. 24.6%
25. How many milliliters of a 2% (w/v) solution of lidocaine hydrochloride should be used in
preparing 500mL of a solution containing 4mg of lidocaine hydrochloride per milliliter of
solution? 100mL
26. Dopamine hydrochloride injection is available in 5mL ampuls containing 40mg of dopamine
hydrochloride per milliliter. The injection must be diluted before administration. If a
physician wishes to use sodium chloride injection as the diluent and wants a dilution
containing 0.04% (w/v) of dopamine hydrochloride, how many milliliters of sodium chloride
injection should be added to 5mL of the injection? 495mL
27. If an antibiotic injection contains 5% (w/v) of the drug, how many milliliters of diluent
should be added to 5mL of the injection to prepare a concentration of 5mg of the antibiotic
per milliliter? 45mL
28. A disinfectant concentrate for surgical instruments contains 6.5% (w/v) of a quaternary
ammonium compound. What is the percentage strength of a solution resulting from the
addition of 60mL of the concentrate to 1 gallon of water? 0.1%
29. You have on hand 800g of a 5% coal tar ointment and 1200g of a 10% coal tar ointment.
a. If the two ointments are mixed, what is the concentration of coal tar in the finished
product? 8%
b. How many grams of coal tar should be added to the product to obtain an ointment
containing 15% of coal tar? 164.7g
30. How many grams of sorbitol solution having a specific gravity of 1.285 and how many
grams (milliliters) of water should be used in preparing 500g of a sorbitol solution having a
specific gravity of 1.225? 394.73g sorbitol, 105.26g water Teixeira 3 ...
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This note was uploaded on 10/15/2010 for the course PHCY 6106 taught by Professor Teixeira during the Fall '10 term at Pima CC.
 Fall '10
 Teixeira

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