The pharmacy receives a prescription for 50 grams of 5% salicylic acid ointment. the pharmacy has a 30% salicylic acid ointment and petrolatum available. using only these products, how much petrolatum should be used to compound the prescription? express the answer in grams. (answer must be numeric; no units or commas; include leading zero when answer is less than 1; round the final answer to the nearest one decimal place.)

In this problem, we can formulate two equations.

First, the overall mass balance of the ointment. The mass of 30% salicylic acid ointment plus the mass of petrolatum must be 50 grams.

x + p = 50

Where x is the mass of 30% salicylic acid ointment and p is the mass of petrolatum

Second, the component mass balance of salicylic acid:

0.3 * x = 50 * 0.05

x = 8.33 g

Therefore the mass of petrolatum to be used is:

x + p = 50

p = 50 – x

p = 50 – 8.33

p = 41.67 g

41.7

it should have an internal chamber and two thermometers sticking out of the top. the internal chamber will also be closed off from the outside.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.