Video: Identifying the Products of the Reaction between Li(s) and H₂O(l)

When Li solid reacts with excess H₂O(l), which of the following are products of the reaction? I) Li⁺(aq) II) OH⁻(aq) III) H₂(g) [A] I only [B] III only [C] I and II only [D] I and III only [E] I, II, and III


Video Transcript

When Li solid reacts with excess H₂O liquid, which of the following are products of the reaction? I) Li⁺ aqueous, II) OH⁻ aqueous, III) H₂ gas. A) I only, B) III only, C) I and II only, D) I and III only, or E) I, II, and III.

Li is the symbol for the element lithium. Lithium can be found in group one of the periodic table. Metals in this area of the periodic table are known as alkali metals. The alkali metals are called alkali metals because when they’re mixed with water, they produce hydroxide ions.

When an alkali metal is put in contact with water, it will react quickly, producing the alkaline metal hydroxide and hydrogen. This is because all alkaline metals are higher up the activity series than hydrogen is. So, alkali metals react with water to release hydrogen.

When we mix it with lots of water, we’ll form dissolved lithium hydroxide and hydrogen gas. And this is how we balance the equation. Two lithium atoms react with two water molecules to produce two units of lithium hydroxide and one hydrogen molecule.

So, so far we definitely know that hydrogen is a product of this reaction. And when we separate out lithium hydroxide into its dissolved ions, we can see we also produce Li⁺ aqueous and OH⁻ aqueous. So, of the five options given, the one that accounts for all the products of the reaction is E: I, II, and III, Li⁺ aqueous, OH⁻ aqueous, and H₂ gas.

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