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Redox reaction from dissolving zinc in copper sulfate

Video transcript

so what we have here is a solution of copper sulfate copper sulfate and copper sulfate is an ionic compound the copper loses two electrons to the sulfate so the copper has a positive two charge and the sulfate has a negative two charge this becomes this isn't a cation and this is an anion so you can imagine it's very easy to dissolve it in a polar solvent like water so this is an aqueous solution we are dissolving it in water and actually does have this blue color so one way to think about it is this is a bunch of copper cations dissolved in water and a bunch of sulfate a bunch of sulfate anions also dissolved in this water right over here now we're going to do a little bit of an experiment we're going to take some solid zinc solid zinc would have this kind of metallic gray color we're going to take a powder of solid zinc metal and throw it into this solution and think about what is going to happen so that's solid zinc right over there so saw zinc in the solid state plus this inside of this solution of copper sulfate what do we think is going to happen and I actually encourage you to pause the video look at this table of electronegativities and look at what's going on here think about who has the electrons and who might want the electrons and then think about what's going to what you think is going to happen well let's look at let's look at the electronegativities right over here copper is more electronegative more electronegative than zinc is and so if there was a way for copper to take electrons from the zinc it would especially this copper right over here these these are positively charged coppers they would love nothing more than to take some electrons and become neutral and look there's someone to take those electrons from and so what you get what you get is a redox reaction and we'll look at the half reactions in a second you get a redox reaction where the copper takes the copper takes electrons from the zinc so be solid copper neutral solid copper and the zinc loses those electrons to the copper and so those become zinc cations or you could think of it as zinc sulfate zinc sulfate dissolved in the aqueous solution so let me write that down zinc sulfate and that has a negative charge still and it is an in an aqueous solution so what will this actually look like so let me put another glass here so this is before the reaction starts after the reaction it's going to look something like this zinc sulfate is actually a clearish looking liquid so let me draw that the liquid will actually become clear so zinc sulfate is a clearish liquid instead of having solid zinc here now you're going to have solid copper now you're going to have solid copper that will have precipitated precipitated out of the solution so that's pretty neat and just so we just to make sure that we understand it in terms of oxidation and reduction let's think about the half reactions here let's think about the half reactions so let's think about the half reaction the half reaction for zinc so zinc zinc here zinc here solid zinc right over here it has a neutral oxidation state it has no charge and then we end up we end up right over here with zinc that has a positive charge a positive two charge so you get two zinc with a positive two charge so what happened right over here it lost electrons it got oxidized so it lost it lost two electrons the zinc got oxidized zinc oxidized the zinc got oxidized and then what happened to the copper well the copper started as a cation so it started in the aqueous solution and then it gained two electrons it gained two electrons each atom or each ion of copper gained two electrons and then we end up with copper we end up with copper in the neutral copper in the solid state so its oxidation number was reduced it became more negative so we could say that the copper was reduced copper reduced by the zinc the zinc oxidized by the copper and we see that the sulfate its charge didn't change and when you're dealing with an actual ionic compound the oxidation state is its actual charge it's not hypothetical anymore