Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: otter on December 07, 2014, 04:30:13 PM
-
I have the following question on homework:
Calculate the mass of P in a sample of CaHPO4 (Dicalcium phosphate).
This seems like a trick question. Would the Phosphorus mass be just as it is in the Periodic table? That is, the answer would be: 30.9g?
I could see if it would be a mass % of the compound, but the question isn't asking for that. So what is there to calculate? What am I missing?
thanks,
Otter
-
I have the following question on homework:
Calculate the mass of P in a sample of CaHPO4 (Dicalcium phosphate).
This seems like a trick question. Would the Phosphorus mass be just as it is in the Periodic table? That is, the answer would be: 30.9g?
I could see if it would be a mass % of the compound, but the question isn't asking for that. So what is there to calculate? What am I missing?
thanks,
Otter
What are the units of the mass in the periodic table?
-
What are the units of the mass in the periodic table?
As I mentioned above, 30.973
-
UPDATE!!! - I'm sorry, I missed a previous part to this question and took it out of context of the greater problem.
See answer below
again, my apologies.
otter
-
@otter
Want to share your insight or answer to the question and how you got it?
-
Sorry, yes, it is probably best I clarify.
My intial question was PART B, of a series of questions that started with this assumption:
You have 0.479 g CHPO4
So therefore, the P mass I am looking for in...
Calculate the mass of P in a sample of CaHPO4 (Dicalcium phosphate).
...is based on having an initial amount of 0.479 g of CHPO4.
Answer to initial question. 0.109g of P.
work: 0.479g CHPO4 x 30.97 g P (atomic mass of P) / 136.06 (mass of CHPO4 ) = 0.109g of P
-
What are the units of the mass in the periodic table?
As I mentioned above, 30.973
Not that it still matters if you have solved the question, but 30.973 is a value, not units.