Solving Acid-Base Reactions: NaOH + HCl → NaCl + H2O

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Discussion Overview

The discussion revolves around a homework problem involving the reaction between NaOH and HCl, specifically focusing on calculations related to the mass of the solution, moles of water and NaCl formed, and the molar heat of reaction. The scope includes conceptual understanding and mathematical reasoning related to acid-base reactions.

Discussion Character

  • Homework-related, Mathematical reasoning, Conceptual clarification

Main Points Raised

  • Post 1 presents a homework statement with specific questions about the reaction and expresses confusion regarding the use of the final concentration of NaCl in calculations.
  • Post 2 suggests that the final concentration of NaCl can be derived from stoichiometry or the final volume, indicating that both methods are valid for calculating the amount of product.
  • Post 3 raises a question about the mass of the solution, debating whether it should be 102g or 100g, referencing guidance from a teaching assistant and a lab manual.
  • Post 4 questions the clarity of the previous posts regarding volume, density, and mass, indicating a need for further clarification.

Areas of Agreement / Disagreement

Participants express differing views on the correct mass of the solution and the appropriate method for calculating the moles of NaCl formed, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

There are unresolved assumptions regarding the definitions of density and volume in the context of the reaction, as well as the implications of using final concentrations versus stoichiometric calculations.

Glen Maverick
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Homework Statement



NaOH(aq) + HCl(aq) ------> NaCl(aq) + H2O(l)

50mL of 1.0M HCl and 50ml 1.0M NaOH was mixed. Total heat is 2826J. If the density of 0.5M NaCl produced in this reaction is 1.02g/mL:
a) What is the mass of the solution?
b) Moles of water formed
c) Moles of NaCl formed
d) Molar heat of reaction

Homework Equations


The Attempt at a Solution



a) 1.02g/ml x 100ml = 102 g
b) 50ml x 0.001 x 1M =0.05 moles of Water
d) 2826/0.05 = 56.52kJ

Iam very confused about c). Why is there "0.5M"in the question? Do I have to use that molarity during calculation?
 
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I am not sure what is so confusing? If you start with amounts of reagents given, you calculate number of moles of NaCl produced, and you check what is the final volume, you will find 0.5 M is just the final concentration of NaCl. I suppose teacher will prefer you to calculate amount of product from the stoichiometry, not from the final concentration, but both ways give correct result.
 
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I get it. :) What I am also confused about is whether the mass of the solution os 102g or 100g. TA said we ar multiplying the dnesity of NaCl to 100ml(50ml+50ml) for finding heat gained by solution. according to the lab manual, the calculation is saying 102 g. However, I think 100g is the mass of the solution.
 
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What volume? What density? What mass then?
 
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