chemistry conversion...lost

katybusymom · Aug 27, 2011

In nursing this problem is called "dimensional analysis". In chemistry it's just a pain in the butt :) However, if you can learn to convert back and forth using this system, then you can you it to do ANY problem you will come across in nursing.

First, realize that chemistry is all about "units". 453.6 grams is equal to 1 pound, so 1 pound contains 453.6 grams.

This is how I set up the problem:

(12 oz. / 6 ) x (1 pound / 16 oz. ) x (453.6 grams / 1 pound) x (51 grams / 100 grams) = 28.9 grams

If you type the equation into a graphing calculator using the parenthesis and "/" symbols and use "*" as multiply, you will come out with the exact same answer.

Go across the top row first. (12*1*453.6*51) = 277603.2

Then the bottom row: (6*16*1*100) = 9600

Divide the top row by the bottom row: 277603.2 / 9600 = 28.9

I hope that explains it. Chemistry is a hard class, but you can do it :)

darling2014 · Aug 27, 2011

The only problem is my professor is not good at explaining things, and since it is more difficult to teach myself due to not understanding the material, I was wondering if someone on here could help me understand why this problem is set up the way it is (this one was done in class for us)
Blueberry fiber cakes contain 51% dietary fiber. If a package with a net weight of 12oz contains six cakes, how many grams of fiber are in each cake?
12oz x 1lbs x 453.6g x 51g
----- ---- ------- ---- --------------- = 28.9g per cake:confused:
6 cakes 16oz 1 lbs 100g
Thank you for your help!

This looks hard but it's not so bad; you've probably done canceling before in math. You can cancel the units themselves, so, the ones that appear on the top and the bottom can cancel each other out, so you get 12x1x453.6x51 g. on the top, and 6x16x1x100 cakes on the bottom. 277603.2 g. / 9600 cakes equals 28.9 g./cake

Reply if you need more help. Good luck! I don't know why but I like these problems:)