[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

[sjb]

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?

[otter]

What are the units of the mass in the periodic table?

As I mentioned above, 30.973

[otter]

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

[billnotgatez]

@otter
Want to share your insight or answer to the question and how you got it?

[otter]

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

[Borek]

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.