541 calculations (exam 1)

percentage error

(error x 100%)/(quantity desired)

6 part per million

0.0006%

express 1:4000 as a percentage strength

4000/1 = 100/x x= 0.025%

calculating volume, knowing the weight and specific gravity

milliliters = grams/specific weight

when ratio strength is given, convert to

percentage strength before setting up a proportion

for dilute solutions, concentrations expressed as

ppm

finding concentration (w/v) given specific gravity and amount in prescription label

specific gravity x amount in prescription

specific gravity example: if 54.96mL of an oil weights 52.78 g, what is the specific gravity of the oil? 54.96 mL of water weighs 54.96 g

weight of substances/weight of equal volume of water 52.78g/54.96g = 0.9603

if a drug contains x%, how many mL can be prepared from X of something

x%/100% = givenX/X if given specific gravity, divide the number given by specific gravity example: 0.9%/100% = 112.5g/x x= 12500mL

express 0.02% as ratio strength

0.02/100 = 1/x x= 5000 1:5000

how many grams of drug should be used in preparing 500mL of a 0.04% solution

0.04%/100 = 0.0004 500g x 0.0004 = 0.2 g

if 500 mL of mineral oil are used to prepare a L of mineral oil emulsion, how many g of the oil, having a specific gravity of 0.87 would be used in preparation of 1 gallon of emulsion

1 gallon = 3785 mL (3785mL) x (500mL/1000mL) x 0.87g/mL) = 1647 g

how many grams of sodium fluoride should be added to 100,000 L of drinking water containing 0.6ppm of sodium fluoride to provide a recommended concentration of 1.75 ppm

1. 1.75ppm - 0.6ppm= 1.15 ppm 2. 10^6/1.15 = 100000000mL/x 3. x= 115mg get 10^8 by making 10^6 to mL and multiplying by 1000

w/v of an ingredient that has percent and also is in mL example: what is percentage concentration (w/v) of methylcelluose? (methylcellulose 1% 50 mL) (total solution: 100mL)

1. 1/100 = x/50mL = 0.5 2. 0.5/100 x 100 = 0.5%

lactic acid 4g salicylic acid 5 g trichloroacetic acid 2 g flexible collodion qs ad 100g flexible collodion contains 20% w/w camphor and 30% w/w castor oil. how many grams of each would be contained in 30 g of the mixture?

1. 100 - all other ingredients (get 89 g) 2. (30g x 89 g)/100 = 26.7 g 3. camphor: (20 x 26.7)/100 = 5.34 g 4. castor oil: (30g x 26.7g)/100 = 8.01 g

if have % (v/v) and want to know how many g should be used in preparation of X mL

1. convert V to mL 2. use specific gravity to get g (multiply by specific gravity) 3. multiply by percent

when solving for percent concentration for something that you added into a solution

1. solve for mg that added (use method of proportion) 2. take above answer and convert to grams 3. take above number and divide by TOTAL volume 4. multiply by 100%

calculate the quantity of each ingredient needed to fill # Xml bottles of formula

1. take # * XmL/bottle to get Y 2. take above number and divide by 100mL 3. multiply each ingredient by this number to get amount of each ingredient

if 5g of drug are added to 100mL of water, what is percentage strength of solution

100 g + 5g = 105g 105g / 5g = 100%/x% x= 4.76%

calculate strength of misoprostol in prescription given misoprostol 200µg tablets and have to make 12

12 x 200 µg = 2400 µg 100 mL of solution has 2400µg 2400/100 = 24 µg/mL 24 µg / 10^6 µg x 100 mg = 0.024 mg/mL

the concentration of a drug additive in an animal feed is 12.5 ppm how many mg of the drug should be used in preparing 5.2 kg of feed

12.5 ppm = 12.5 g drug/ 1,000,000 g feed 1,000,000g/12.5 = 5,200 g/xg x= 0.065 g or 65 mg

how many grams of drug should be used in preparing 500mL of a 1:2500 solution

2500mL/500mL = 1g/xg x= 0.2 g

a drug is available in a refilled syringe containing 40mg/0.8mL of injection. Calculate the concentration of drug on a mg/mL basis

40mg/0.8mL = xmg/1mL x= 50 mg

adds 10 mL of 20% solution of drug to 500mL of something what is percentage strength of drug in solution

500 + 10 = 510mL total (find total concentration first) 20% (10mL) = x% (510mL) x= 0.39%

how many grams required to prepare X mL of a X% solution example: how many g in 4000mL of a 5% solution?

5g/100mL x 4000 mL = 200 g

specific gravity to find mL from grams Example the specific gravity of castor oil is 0.955. How many mL of oil are contained in 30g of mixture (determined to be 8.01 earlier)

8.01g/0.955 = 8.39

dilution concentration

Q1 x C1 = Q2 x C2

when doing proportion calculations, the concentration that you are tying to produce needs to

be a value in between the other 2 percentages that are in the "square" that you are calculating in (so if tying to get a 10% and have 20, 15, 5, and 3 can have 20 + 5 and 15 + 3 but can't have 5 + 3)

Neupogen profiled syringes contain 480 mcg of active constituent in each 0.8mL. The equivalent concentration is

concentration is in g/mL 0.00048g/0.8mL=0.0006 0.006 x 100% = 0.06%

milligrams percent (mg %)

expresses the number of mg of a substance in 100 mL of liquid

solving for percentage concentration when have solid in solid

g of preparation x %concentration = g of component

calculating weight, knowing volume and specific gravity

grams = milliliters x specific gravity

solving for percentage concentration when have solid in liquid

mL of preparation x % concentration = g of component

solving for percentage concentration when have liquid in liquid

mL of preparations x %concentration = mL of component