Percentage, Ratio Strength and Other Expressions of Concentration (Part 1)

Question 1

expresses the number of grams of a constituent
in 100 mL of a solution or liquid preparation and it is used regardless whether water or another liquid in the solvent or vehicle.

Answer 1

Percent weight in volume (w/v)

Expressed as: ____% w/v.

Question 2

expresses the number of milliliters of a constituent in 100 mL of a solution or liquid preparation.

Answer 2

Percent volume in volume (v/v)

Expressed as: ____% v/v.

Question 3

expresses the number of grams of a constituent

in 100 g of solution or preparation.

Answer 3

Percent weight in weight (w/w)

Expressed as: ____% w/w.

Question 4

The term percent, or the symbol %, when used without qualifications means:

For solutions or suspensions of solids in liquids;

Answer 4

percent weight in volume

Expressed as: ____% w/v.

Question 5

The term percent, or the symbol %, when used without qualifications means:

For solutions of liquids in liquids;

Answer 5

percent volume in volume

Expressed as: ____% v/v.

Question 6

The term percent, or the symbol %, when used without qualifications means:

For mixtures of solids or semi-solids;

Answer 6

percent weight in weight

Expressed as: ____% w/w.

Question 7

The term percent, or the symbol %, when used without qualifications means:

For solutions of gases in liquids;

Answer 7

percent weight in volume

Expressed as: ____% w/v.

Question 8

Solve the following:
1. Rx
Antipyrine 5%
Glycerin, ad 60
Sig: 5 drops in right ear
How many grams of antipyrine should be used in preparing the prescription?
Note: answer whole number space unit, abbreviated

Answer 8

The correct answer is: 3 g

Question 9

What is the percentage strength (v/v) if 225 g of liquid (Sp gr 0.8 ) is added to enough water to make 1.5 L of the solution?
Note: answer should be in percent (%) and 2 decimal places, answer/space/unit

Answer 9

The correct answer is: 18.75 %

Question 10

A metronidazole gel contains 0.75% of a drug in 70-g tubes. An applicator can hold 5 g of a gel for each administration. How much drug, in milligrams, will be contained in each application?
Answer: with one decimal place, answer/space/ unit abbreviated

Answer 10

The correct answer is: 37.5 mg

Question 11

Aluminum chloride is soluble in 1 in 4 alcohol. How much aluminum chloride, in kilogram, can be dissolved in 1.6 L of alcohol?
Note: Answer is one decimal place only, answer/space/unit

Answer 11

The correct answer is: 0.4 kg

Question 12

How much coal tar solution 2% w/v would contain 140 mg of coal tar?
Note: Answer is a whole number/space/unit

Answer 12

The correct answer is: 7 mL

Question 13

Express 2 g of active ingredient in 250 mL of solution as ratio strength.
Note: No spaces between the number and the ratio sign
Lowest term

Answer 13

The correct answer is: 1:125

Question 14

You require 90 mg of cocaine hydrochloride. How many milliliters of a 1:400 solution is equivalent to this amount?
Note: Answer is a whole number/space/unit

Answer 14

The correct answer is: 36 mL

Question 15

Ster-Zac Bath Concentrate contains 2% triclosan and to prevent cross infection, 28.5 mL should be put in a bath. How much triclosan would the bath contain.
Note: answer should be two decimal places only/space/unit

Answer 15

The correct answer is: 0.57 g

Question 16

Nerisona cream contains 0.1% w/w of difluocortolone valerate. How much difluocortolone valerate is contained in a 30-g tube?

Answer 16

The correct answer is: 30 mg

Question 17

Marcain with adrenaline contains adrenaline as a strength stated as 1 in 200,000. Express this strength as a percentage.
Note: Answer should be 4 decimal places/ space / unit

Answer 17

The correct answer is: 0.0005 %

Question 18

Acyclovir cream has a stated strength of 5% w/w . Express this strength as a ratio strength.

Answer 18

The correct answer is: 1:20

Question 19

You dispense a 13.5 mL bottle of sodium cromoglicate at 2% eye drops. How much sodium cromoglicate, in milligram, does the bottle contain?

Answer 19

The correct answer is: 270 mg

Question 20

A patient is dispensed a 10-mL bottle of chloramphenicol 5% ear drops . How much chloramphenicol, in milligram, is present in the bottle?

Answer 20

The correct answer is: 500 mg

Question 21

A patient is dispensed a 10-mL bottle of chloramphenicol 5% ear drops . If there are 20 drops in 1 mL, how much chloramphenicol is there in each drop, expressed in micrograms.
Note: use the abbreviated unit mcg

Answer 21

The correct answer is: 250 mcg

Question 22

If a liquid vitamin preparation contains 0.16 micrograms of vitamin B12 per 5 mL, what is the ratio strength of the preparation?
Separate thousand/millions with a comma

Answer 22

The correct answer is: 1:31,250,000