Calculating Moles from Given Mass: Where Did I Go Wrong?

  • Thread starter Thread starter JEscribir
  • Start date Start date
  • Tags Tags
    Stoichiometry
Click For Summary

Discussion Overview

The discussion revolves around calculating the number of moles of chloral hydrate (C2H3Cl3O2) from a given mass of 100.0 grams. Participants explore the process of converting grams to moles, clarify the molar mass, and question the correctness of the initial calculations.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on how to calculate moles from grams, indicating initial confusion about the question's requirements.
  • Another participant presents the specific problem involving 100.0 g of chloral hydrate and calculates the number of moles using a molar mass of approximately 165.4 g/mol, arriving at about 0.6064 moles.
  • A third participant confirms the molar mass calculation as correct and provides a slightly different value for the number of moles (0.6046), suggesting that the original poster should consult their teacher regarding the exercise.
  • One participant expresses skepticism about the teacher's potential mistake, noting that others have completed the assignment without issue.
  • Several participants inquire about the correct answer, indicating uncertainty about the correctness of the calculations presented.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the initial calculation is correct or if there is a mistake in the problem itself. Multiple viewpoints exist regarding the accuracy of the calculations and the teacher's role in the potential misunderstanding.

Contextual Notes

There is a lack of clarity regarding the expectations of the problem, as well as potential discrepancies in the interpretation of significant figures and rounding in the calculations.

JEscribir
Messages
17
Reaction score
0
Can someone show me how to calculate the number of moles of a given compound's molecules when given the mass in grams of the compund sample?

I am kind of confused by this because at first I thought it just asked for me to convert the grams into moles, but that isn't exactly what is being asked.
 
Physics news on Phys.org
The actual problem that I don't understand says " how many moles of C2H3Cl3O2 molecules are in 100.0 g chloral hydrate (C2H3Cl3O2)?"

So that's to four sig figs and chloral hydrate has a molar mass of about 165.4 g/mol. I divided 100.0g / 165.4 g per mol to get about .6064 moles, but I'm getting that, it is incorrect.
So did I do something wrong or is it a mistake by the teacher?
 
Did you calculated the molar mass of C_2H_3Cl_3O_2 or it was given by your teacher? Anyway, the molar mass of C_2H_3Cl_3O_2 is 165.403 g.mol-1 which is the value you got.
Then, the number of moles is 0.6046.Honestly, I do not see anything wrong in what you have done. You should ask your teacher to revise this exercise.
 
Last edited by a moderator:
Yeah I emailed my teacher because I was freaking out since I could have sworn I did it right.

Other people have already finished the assignment and no one has pointed out the supposed mistake to be revised that is why I am so skeptical.
 
Do you have the solution?
 
what do you mean by solution?
 
You say that you are incorrect. Then, you should know the correct answer. That's what I am asking. Which is the correct answer to this problem?
 
JEscribir said:
So that's to four sig figs and chloral hydrate has a molar mass of about 165.4 g/mol. I divided 100.0g / 165.4 g per mol to get about .6064 moles, but I'm getting that, it is incorrect.
So did I do something wrong or is it a mistake by the teacher?
I too get that as my answer.
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
3
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K
Replies
1
Views
2K
  • · Replies 14 ·
Replies
14
Views
12K
  • · Replies 5 ·
Replies
5
Views
3K
Replies
2
Views
3K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K