MHB Troubleshooting Mastering Chemistry: P4 + O2 → P2O5

AI Thread Summary
The discussion centers on troubleshooting a chemistry problem in Mastering Chemistry regarding the reaction P4 + O2 → P2O5. The user initially submitted answers in grams, which caused an error message about unrecognized units. It was clarified that the problem requires answers in moles, not grams, and that units should be omitted. The correct calculation for part A shows that 186 g of P4 yields 3.0 moles of P2O5. The conversation highlights the importance of understanding units and conversions in chemistry assignments.
Teh
Messages
47
Reaction score
0
I am stuck on this chemistry problem using Mastering Chemistry to do my homework. This is the problem. When I enter the answers it keeps saying is that "One or more of the units you entered is not recognized."

**My Answers**For part A my answer was 426 g P2O5

and for part B 369 g P2O5**Problem**

Consider a situation in which 186 g of P4 are exposed to 208 g of O2.P4+5O2→2P2O5PART A) What is the maximum amount in moles of P2O5 that can theoretically be made from 186 g of P4 and excess oxygen?
PART B) What is the maximum amount in moles of P2O5 that can theoretically be made from 208 g of O2 and excess phosphorus?
 
Mathematics news on Phys.org
Hi Teh! ;)

The problem is asking for the number of moles.
So the answers shouldn't be in grams.
Moreover, the unit should be left out.

Note that to find moles from grams we have to divide by the atomic mass in atomic mass units.
So for instance 32 g of $O_2$ is 1 mole of $O_2$.

For part $(A)$ we have 186 g phosporus and $P$ has an atomic mass of 31 amu, or 31 g/mol.
That makes:
$$\frac{186}{31} = 6.0 \text{ mol of P atoms}$$
The reaction is:
$$P_4 + 5O_2 \to 2P_2O_5$$
The resulting product has $P_2$ in it, meaning 2 $P$ atoms per molecule, so there will be:
$$\frac {6.0} 2 = 3.0 \text{ mol of $P_2O_5$ molecules}$$

So the requested number of moles is $3.0$.
 
thank you so much! uhh hate online homework thank you!
 
Suppose ,instead of the usual x,y coordinate system with an I basis vector along the x -axis and a corresponding j basis vector along the y-axis we instead have a different pair of basis vectors ,call them e and f along their respective axes. I have seen that this is an important subject in maths My question is what physical applications does such a model apply to? I am asking here because I have devoted quite a lot of time in the past to understanding convectors and the dual...
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...
Back
Top