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General Chemistry Principles, Patterns, and Applications, 2011

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B Two moles of lithium are required to balance the equation: 2Li(s) + CH 3Cl(l) → LiCl(s) + CH 3Li(soln).<br />

e. A Lithium nitride <strong>and</strong> potassium chloride are largely ionic compounds. The nitride ion (N 3− ) is a very<br />

strong base because it is the fully deprotonated form of ammonia, a weak acid. An acid–base reaction<br />

requires an acid as well as a base, however, <strong>and</strong> KCl is not acidic. What about a redox reaction? Both<br />

substances contain ions that have closed-shell valence electron configurations. The nitride ion could act<br />

as a reductant by donating electrons to an oxidant <strong>and</strong> forming N 2. KCl is not an oxidant, however, <strong>and</strong> a<br />

redox reaction requires an oxidant as well as a reductant.<br />

B We conclude that the two substances will not react with each other.<br />

Exercise<br />

Predict the products of each reaction <strong>and</strong> balance each chemical equation.<br />

a. K(s) + N 2(g) →<br />

b. Li 3N(s) + H 2O(l) →<br />

c. Na(s) + (CH 3) 2NH(soln) →<br />

d. C 6H 5Li(soln) + D 2O(l) → C 6H 5D(l) + LiOD(soln)<br />

e. CH 3CH 2Cl(soln) + 2Li →<br />

Answer:<br />

a. no reaction<br />

b. Li 3N(s) + 3H 2O(l) → NH 3(aq) + 3LiOH(aq)<br />

Na s<br />

c.<br />

( ) +(CH 3)2NH ( soln)<br />

( ) + Na[(CH 3)2N] ( soln)<br />

®12H 2 g<br />

d. C 6H 5Li(soln) + D 2O(l) → C 6H 5D(l) + LiOD(soln)<br />

e. CH 3CH 2Cl(soln) + 2Li → CH 3CH 2Li(soln) + LiCl(soln)<br />

Summary<br />

The first alkali metals to be isolated (Na <strong>and</strong> K) were obtained by passing an electric current through<br />

molten potassium <strong>and</strong> sodium carbonates. The alkali metals are among the most potent reductants<br />

known; most can be isolated by electrolysis of their molten salts or, in the case of rubidium <strong>and</strong> cesium, by<br />

reacting their hydroxide salts with a reductant. They can also be recovered from their silicate ores using a<br />

multistep process. Lithium, the strongest reductant, <strong>and</strong> sodium, the weakest, are examples of the<br />

physical <strong>and</strong> chemical effects of opposing periodic trends. The alkali metals react with halogens (group 17)<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

1951

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