How do you write neutralization reactions backwards (with the reactants as the salt and water)?

Question

For example:

NaOCH3 (s) + H2O (l) -->

Al4C3 + H2O (l) -->

Thank you!!!

Answer 1

These are hydrolysis reactions (reactions with water). As such, you will use H⁺ and OH^- from water to form the products.

NaOCH3(s) + H-OH ==> Na-OH + CH3O-H

sodium methoxide + water ==> sodium hydroxide + methanol

Al₄C₃ + H-OH ==> Al-OH + C-H ... unbalanced

We know that Al-OH is actually Al(OH)₃ and C-H is actually CH₄, so...

Al₄C₃ + 12H-OH ==> 4Al(OH)₃ + 3CH₄

Aluminum carbide + water ==> aluminum hydroxide + methane

Answer 2

In reactions like this, you would have to recognize the acid and conjugate base, and vice versa

For example, in NaOCH3 (s) + H2O (l) -->

CH3O- is the base in this reaction, since it lost a proton is shown by how we know CH3O- has a negative charge which allows it to ionically bond with Na+, therefore its conjugate acid is CH3OH

Conversely, this also means that H2O is the acid, which means the conjugate base is OH-

so the whole reaction would be NaOCH3 (s) + H2O (l) --> CH3OH + OH-

In the second example, in the reaction Al4C3 + H2O ->

This reaction is not a neutralization reaction, but is instead a hydrolysis reaction; aluminum is known to form a weak base in aluminum hydroxide, so we know Al(OH)3 is a product

We can then assess that CH4 is produced from the remaining protons, since it is the most stable product available

Al4C3 + 12H2O -> 3CH4 + 4Al(OH)3

Answer 3

Hello, thank you for taking the time to post your question!

The underlying idea in this type of reaction is that the liquid water and the solid salt reactants will break down, then the water’s hydrogen and the hydroxide ions combine with the ions of the salt to form an acid and a base.

For the examples you gave that would lead to

NaOCH3 (s) + H2O (l) -> CH3OH (l) + NaOH (aq)

Al4C3 (s) + 12 H2O (l) -> 4 Al(OH)3 (s) + 3 CH4 (g)

for the balanced equations!

Hopefully that gets you moving in the right direction! Feel free to reach out if you have any questions beyond that :)