Molecular percent of compounds

In summary, the conversation discusses the conversion between mass and moles in compost x, as well as the calculation of additional moles of D2 needed. It also includes equations for molar mass and the total moles. The final result is that 2.1 grams of D2 needs to be added to the compost x.
  • #1
LCSphysicist
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Homework Statement
All below
Relevant Equations
All below
1597489453726.png


mx remets to mass in gram of the compost x
nx remets to moles of the compost x
nTot remets to the total moles
x remets to the additional moles of D2
I considered the molar mass:
MH2 = 2u
MHD = 3u
MD2 = 4u

10 = mH2 + mHD + mD2
10 = nH2*2 + nHD*3 + nD2*4
10 = nTot + 0.9nTot + 0.8nTot
nTot = 10/2.7

So:
0.3 = (nD2 + x)/nTot + x
x = nTot/7
x = 10/(18.9)

That is, we need to add + 10/(18.9) moles of D2,
10/(18.9) = m/4
m = 2.1 g

This seems right?
 
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  • #2
LCSphysicist said:
Homework Statement:: All below
Relevant Equations:: All below

View attachment 267794

mx remets to mass in gram of the compost x
nx remets to moles of the compost x
nTot remets to the total moles
x remets to the additional moles of D2
I considered the molar mass:
MH2 = 2u
MHD = 3u
MD2 = 4u

10 = mH2 + mHD + mD2
10 = nH2*2 + nHD*3 + nD2*4
10 = nTot + 0.9nTot + 0.8nTot
nTot = 10/2.7

So:
0.3 = (nD2 + x)/nTot + x
x = nTot/7
x = 10/(18.9)

That is, we need to add + 10/(18.9) moles of D2,
10/(18.9) = m/4
m = 2.1 g

This seems right?
That's what I get. Nice job.
 
  • Informative
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1. What is the definition of molecular percent of compounds?

The molecular percent of compounds is a measure of the relative abundance of each element in a chemical compound. It is calculated by dividing the mass of a specific element in a compound by the total mass of the compound and multiplying by 100.

2. How is molecular percent of compounds different from molar mass?

Molecular percent of compounds and molar mass are two different ways of expressing the composition of a compound. While molecular percent of compounds gives the relative abundance of each element, molar mass gives the total mass of the compound in grams per mole.

3. Can molecular percent of compounds be negative?

No, molecular percent of compounds cannot be negative. It is always expressed as a positive value, representing the percentage of a specific element in a compound.

4. How is molecular percent of compounds used in chemistry?

Molecular percent of compounds is used in various applications in chemistry, such as determining the empirical formula of a compound, calculating the percent composition of a compound, and identifying unknown substances through elemental analysis.

5. How do you calculate molecular percent of compounds?

To calculate the molecular percent of compounds, you need to know the mass of each element present in the compound and the total mass of the compound. Then, divide the mass of each element by the total mass and multiply by 100 to get the percentage. Finally, add up the percentages of all elements to get the molecular percent of compounds.

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