Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: elynsam123 on July 30, 2016, 05:26:55 PM

Title: chemistry help please
Post by: elynsam123 on July 30, 2016, 05:26:55 PM

I am having trouble with a review question. i know the answer since it is given in the back of the book. but i dont know how to get there.
How many grams of Ba3P2 would contain 4.23 g of Ba, if Ba3P2 contains 86.9% Ba by mass?

i know you use 86.9g Ba/100g ofBa3P2
i tried also converting 4.23 g Ba to moles but am having trouble with it all.

Title: Re: chemistry help please
Post by: mikasaur on July 30, 2016, 06:07:14 PM

You won't need to convert to moles. You're right that you'll need the ratio you have, but you may need to flip it. Think about that...

Title: Re: chemistry help please
Post by: Arkcon on July 30, 2016, 09:10:59 PM

How many gumballs do I need to have, if I need 10 red gumballs, and the ones I have are half blue, and half red?

You have a slightly more difficult ratio, and your question asks for elements instead of gumballs, but the math is the same.