Stoichiometry Gold III hydroxide

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Discussion Overview

The discussion revolves around a stoichiometry problem involving the reaction of KAuCl4 with sodium carbonate to produce gold III hydroxide. Participants explore the balanced chemical equation, the concept of limiting reactants, and percent yield calculations.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • The original poster presents a balanced equation attempt and expresses confusion regarding the transition from carbonate (CO3) to carbon dioxide (CO2) in the reaction.
  • Some participants clarify that CO2 is not a polyatomic ion but a compound, and they suggest that the decomposition of CO3 is likely due to the acid character of Au3+.
  • There is a discussion about determining the limiting reactant, with a participant noting that the smaller number of moles does not automatically indicate the limiting reactant and suggesting a method to calculate the amount of product from each reactant.
  • The original poster calculates the theoretical yield of gold III hydroxide and the percent yield based on the actual amount produced.

Areas of Agreement / Disagreement

Participants generally agree on the need for a balanced equation and the concept of limiting reactants, but there is no consensus on the specific details of the reaction mechanism or the balancing of the equation.

Contextual Notes

There are unresolved questions regarding the balancing of the chemical equation and the interpretation of the stoichiometric relationships between reactants and products.

Who May Find This Useful

Students studying stoichiometry, chemistry educators, and individuals interested in chemical reactions involving gold compounds.

MichaelXY
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Homework Statement


This problem is giving me trouble on many levels.
Gold III hydroxide is used for electroplating gold onto other metals. It can be made from the reaction of KAuCl4 (aq) with sodium carbonate and water.

a. Write a balanced equation for this reaction.

b. To prepare a fresh supply of gold III hydroxide, a chemist makes 20.00g of the KAuCl4 with 25.00 g of the sodium carbonate. What is the percent yield if the actual amount of gold III hydroxide produced in the reaction is 10.56g?




Homework Equations





The Attempt at a Solution


Part (a) is my first difficult spot, I was able to come up with

NaCO3 + KAuCl4 + H2O -------> So I figure Au(OH)3 + KCL + CO3, before balancing
But the correct answer is:
3NaCO3 +2KAuCl4+3H20----> 2Au(OH)3 +2KCL+CO2 +6NACl

My first problem was that I do not see how we went from CO3 to CO2, second since CO3 and CO2 are polyatomics, how do we balance.

So I then went on to work the problem.
20 g KAuCl4 = .05292 moles
25 g NaCO3 = .301 mole

So since KAuCL4 is the smaller amount do I say that is the limiting factor? Assuming I am correct, I compute:

20 g KAuCl4 (1 mole KAUCl4/377.877g KAuCl4) (2 mole AuOH3/ 2 mole KAuCl4) (247.991 g AuOH3/ 1 mole AuOH3) = 13.125 g

So Actual over theo gives 80.45%
As any of that correct?
Thanks
 
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Ok, I thought my question here was valid. Read the forum rules, I showed my work, yet no response. I am somewhat puzzled why I received no response. Could someone explain where my question became unreasonable?

Thanks
 
Your question was not unreasonable and you showed good effort. It just may be that no one could offer any help yet.

MichaelXY said:
13NaCO3 +2KAuCl4+3H20----> 2Au(OH)3 +2KCL+CO2 +6NACl

My first problem was that I do not see how we went from CO3 to CO2, second since CO3 and CO2 are polyatomics, how do we balance.


Na2CO3 is the correct formula and the equation is not balanced and CO2 is not a polyatomic -it is a compound

The decomposition of CO32- is likely due to the acid character of Au3+ (high charge but kind of a big ion) --> Au3+(H2O)6 --> H+ + Au(H2O)5(OH)2+

The H+ then would react with the CO32- and decompose to H2O and CO2.

For the stoichiometry, the smaller no. of moles of reactant does not make it the limiting reactant -
- Use each mol value and determine how many mol of product can be produced.
- How can this information be used to determine which one is the limiting reactant?
 
Thanks for your help. Much appreciated :)
 

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