Select the most likely product for this reaction:
[tex]KOH ( aq )+ CO _2(g) \rightarrow[/tex] ?
A. [tex]K _2 CO _3( aq )+ H _2 O ( l )[/tex]
B. [tex]K ( s )+ H _2(g)+ O _2(g)[/tex]
C. [tex]K ( s )+ CO _3(g)+ H _2[/tex]
Answer (2)
K O H reacts with C O 2 in an acid-base neutralization reaction.
The products are potassium carbonate ( K 2 C O 3 ) and water ( H 2 O ).
Unlikely products like elemental potassium, hydrogen, and oxygen are not formed under these conditions.
The most likely product is K 2 C O 3 ( a q ) + H 2 O ( l ) .
Explanation
Understanding the Reaction The reaction between potassium hydroxide ( K O H ) and carbon dioxide ( C O 2 ) is a classic example of an acid-base neutralization. In this scenario, carbon dioxide acts as an acidic oxide, reacting with the base potassium hydroxide to form a salt and water. Let's break down why this happens and what products are most likely to form.
Identifying Reactants and Their Roles Potassium hydroxide ( K O H ) is a strong base. Carbon dioxide ( C O 2 ) in aqueous solution forms carbonic acid ( H 2 C O 3 ), which is a weak acid. The reaction between them will yield a salt and water.
Determining the Products The salt formed will consist of the cation from the base ( K + ) and the anion from the acid ( C O 3 2 − ), resulting in potassium carbonate ( K 2 C O 3 ). The other product is water ( H 2 O ). Therefore, the balanced reaction is: 2 K O H ( a q ) + C O 2 ( g ) r i g h t a rro w K 2 C O 3 ( a q ) + H 2 O ( l )
Eliminating Unlikely Products Now, let's consider the other options:
K ( s ) + H 2 ( g ) + O 2 ( g ) : This suggests a decomposition reaction, which is highly unlikely under these conditions. It would require a significant energy input to break down K O H and C O 2 into their elemental forms.
K ( s ) + C O 3 ( g ) + H 2 : This option is also not feasible. Potassium does not exist as a free element in aqueous solution due to its high reactivity with water.
Conclusion Based on the principles of acid-base neutralization, the most likely product of the reaction between K O H ( a q ) and C O 2 ( g ) is potassium carbonate and water: K 2 C O 3 ( a q ) + H 2 O ( l )
Examples
Consider a scenario where you need to remove carbon dioxide from a closed environment, such as a submarine or a spacecraft. Potassium hydroxide can be used to scrub the air by reacting with the carbon dioxide exhaled by the crew. The reaction produces potassium carbonate, effectively removing the C O 2 from the air and maintaining a breathable atmosphere. This is a practical application of acid-base chemistry in life support systems.
The reaction between KOH and CO2 produces potassium carbonate and water, making the most likely product A: K2CO3(aq) + H2O(l). This is an acid-base neutralization reaction where KOH neutralizes the weak acid formed from CO2. Thus, the balanced reaction is 2 KOH + CO2 → K2CO3 + H2O.
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