Calculations II

Question 1

PPM

Answer 1

1 part drug : 1,000,000 parts total

Question 2

equation time: specific gravity

Answer 2

weight divided by volume

g/mL (1 gram of water takes up the space of 1 mL)

Question 3

alligation

Answer 3

• high [ ] minus desired [ ] = parts of low [ ]
• desired [ ] minus low [ ] = parts of high [ ]
• take the above calculated parts and add them together to get the total number of ‘parts’ the final product will have
• total number of parts multipled by desired [ ] = total final volume
• total final volume divided by parts = drug per part
• drug per part multipled by parts of high [ ]= amount of the high [ ] to use
• drug per part multiped by parts of low [ ] = amount of the low [ ] to use

Question 4

equation time: osmolarity

Answer 4

mOsmol/L = [wt of substance (g/L) divdided by molecular weight (g/mol)] multiplied by # of particles multiplied by 1000

of particles being how many parts it dissociates into

Question 5

equation time: E value

and how to use it

Answer 5

(58.1 x i) divided by (MW of drug x 1.8)

i = 1 if drug doesn’t dissociate. add 0.8 for every ion (NaCl = 1.8)

Interpretation
- since NS is isotonic, calculate how much NS mgs (9g/100mL) are needed to make the volume perfectly isotonic
- from there, calculate how many mg of the drug you are going to need
- multiply the mg of drug and the E value to get mg of NS represented by drug
- take your initial NS mg calcuation and subtract the value from the above step to get how many mg of NS will need to be added to make it isotonic

Question 6

equation time: mol and mmol

Answer 6

• mol = g / MW
• mmol = mg / MW

Question 7

equation time: mEq

Answer 7

• (mg x valence) / MW
• mmols x valence

valence: the positive charge of compound (what is the net psotive charge when everything dissociates)