Unformatted text preview: Solutions and Reactions Qmﬁans: Q13. QM. Chapter 7 The bond between each NH; and Cu2+ arises ﬁ'om the unshared (or "lone")
pair of electrons on the N of NH; being shared with Cu2+ What IS unusual
about this type of covalent bond' 1s that both of the shared electrons come
from the same atom Sometimes these bonds are called coordinate-covalent
bonds. Now add 2 more drops of CuSOt to the complex ion. Stir. The net reaction is Cu2*(aq) + 20H'(aq) 4 Cu(OH)2(s)
Now why did that happen? Hint: We swamped it with CuSOe!
One more type of reaction. React I drop CuSO4 and 1 drop [(1. Stir. Ugly. Now drop 1 drop of Starcthl test solution very close to (but no! in) the
reaction mixture. Wait and watch. Starcthl is an excellent probe for molecular iodine, [1. The reaction must
have produced I; as a product. Since the Kl solution contains 1’, then
during the reaction to 211m) -> Iraq) + 2 electrons (12(aq)-> 12(3)) electrons are produced as 1' goes to 12. Something must react with the
electrons and it is Cu”: (ii) 20111an + 2 electrons —> 2&1an If we add these two reactions, (i) and (ii), we will get the net ionic reaction 2Cu2+(aq) + 211an a 2Cu"(eq) + l;(aq) This type of reaction is called a reductiomoxr‘darion reaction (redox)
because it is a combination of reduction [gain of electrons by Cuz‘ , reaction (ii)] and oxidation [loss of electrons by 1‘. reaction (i)]. Redox reactions are
reactions in which electrons are transferred from one chemical species to another. In this example, from I' to Cu“.
Clean up as usual. Write out the full ionic and the net ionic equation for the reaction between
HCl and NaOH solutions. (The net ionic equation is, by the way, the same
for most acid-base reactions.) Write out the full ionic and the net ionic equation for the reaction between
CuSOt and K1 solutions. Show your answers to 013 and 014 to your Instructor before moving
011. 7-19 ...
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- Spring '08