Wk7 #4 [ENDORSED]

[Jaclyn Padilla]

Gold has always been a highly prized metal, and it has been widely used from the beginning of history as a store of value. It does not rust like iron and does not become tarnished like silver. It is so chemically inert that it will not react with even the strongest concentrated acids. But it can be dissolved in aqua regia, a fresh‑prepared mixture of concentrated HNO3 and HCl in a 1:3 ratio.

When Germany invaded Denmark in World War II, the Hungarian chemist George de Hevesy dissolved the gold Nobel Prizes of Max von Laue and James Franck in aqua regia to prevent the Nazis from stealing them. He placed the jar with the solution on a shelf in his laboratory and, after the war, precipitated the gold from the acid solution and returned it to the Royal Swedish Academy of Sciences and the Nobel Foundation, who recast the medals and again presented them to Laue and Franck.

The unbalanced equation for the reaction of gold with aqua regia is given. Add the stoichiometric coefficients to the equation to balance it.


How would I put together an equation ?

[Vanessa Nicoll 3H]

First you would assign the oxidation states to all species in the equation. Then you would write the half-reactions in order to balance the reaction. By doing this, you should be able to find the coefficients in order to balance it.

[Anna_Aldridge_2C]

Hi, if I remember correctly, Achieve will give you the unbalanced equation. Is there an unbalanced equation that it gives you?

In the chance it doesn't, I can help explain how to balance the equation in general. I was confused with this equation initially, but I believe all you have to do is balance it like a regular equation because it is already balanced electrically. Like it says in the problem, just add the stoichiometric coefficients based on the ratio they give you (which I believe I did to HCl and H20). Hope this helps!

[Chem_Mod]

Assign the oxidation states to all species in the equation.

In the most compounds, oxygen has an oxidation state of −2 and hydrogen has an oxidation state of +1.