Scored # 10 C/P

[salemstein]

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Kinda confused by the reasoning behind this question... Which one do you want to label and why?

Bonus question: When psychologists say "you master conservation during the formal observation stage. etc" do they mean you master it at the beginning, during the middle, or towards the end of the critical years?

 

[aldol16]

Well, both the acetic acid H and alcoholic H are lost in the reaction so no matter where the OH leaves from, you'll get HDO as your product. So A and B can be eliminated. C can also be eliminated because it doesn't leave at all in the esterification process and doesn't tell you about where the H20 oxygen comes from. If you use 18-O in ethanol and it appears in product, you would know that it contributed the OH that made water. If it appears on product, then you know that acetic acid contributed the OH that made water.

 

[rhinzaz]

Aldol16's explanation regarding your first question is on point. In regards to your bonus question, i'm assuming you mean concrete operational stage rather than formal "observation" stage, referring to Piaget's theory of cognitive development. It's hard to say exactly when during the concrete operational stage that the principle of conservation will be 'mastered' since every individual is different, rather the general age is a range between 7-11 years.