What Steps Solve a Complex Molarity Problem?

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Discussion Overview

The discussion revolves around solving a complex molarity problem presented in a homework statement. Participants explore the correct application of molarity equations and the necessary steps to arrive at the solution, focusing on the relationship between moles, volume, and the specific ions involved in the problem.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • Some participants express confusion about how to correctly apply the equation for molarity, stating that they struggled with unit cancellation.
  • One participant asserts that the equation "Molarity = moles * volume" is incorrect, although no alternative equation is provided.
  • Another participant clarifies that molarity is defined as moles per liter (mol/L) and suggests determining the ratio of Na+ in Na3PO4 to solve the problem.
  • Participants propose setting up a ratio involving Na+ and Na3PO4 concentrations, indicating that the choice of ratio depends on whether the answer should be greater than or less than 1.
  • There is a request for a worked-out solution to help clarify the steps needed to solve the problem.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct application of the molarity equation, and there are competing views regarding the correct approach to solving the problem. The discussion remains unresolved with multiple perspectives presented.

Contextual Notes

Limitations include potential misunderstandings of the molarity equation and the specific ratios involved in the problem. The discussion also reflects uncertainty about the correct interpretation of the problem statement.

pasido
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Homework Statement


http://i.imgur.com/Rz0qB.png


Homework Equations


The answer is B, but I would like to know how to find the answer.
Molarity = moles * volume


The Attempt at a Solution


Yep, I tried for 15+ minutes and couldn't get the darn units to cancel out. A worked out solution would be very helpful.
 
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pasido said:

Homework Statement


http://i.imgur.com/Rz0qB.png


Homework Equations


The answer is B, but I would like to know how to find the answer.
Molarity = moles * volume


The Attempt at a Solution


Yep, I tried for 15+ minutes and couldn't get the darn units to cancel out. A worked out solution would be very helpful.

Is there a reason you have provided an image, rather than text?

How many moles of Na+ do you need?
 
The relevant equation, "Molarity = moles * volume", is wrong.
 
Molarity = mole per liter or mol/L

Determine the ratio of Na+ in Na3PO4 by observing the formulas (*Hint 1/3 or 3/1). Multiply this by your Molar concentration of Na+ given in the problem.

Next, set up a ratio of:

[Na*(1/3 or 3/1) (M)] / Na3PO4 (M)

or

Na3PO4 (M) / [Na*(1/3 or 3/1) (M)]

(reason whether the answer should be greater than 1 or less than 1 to determine which ratio to use).

Finally multiply this by the volume you're trying to prepare.
 

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