Is there a method or way that makes writing the formula for the salt solution for a weak acid/weak base easier?
For example, this is question 7 in the week 2 achieve homework:
HClO is a weak acid (Ka=4.0×10−8) and so the salt NaClO acts as a weak base. What is the pH of a solution that is 0.088 M in NaClO at 25°C?
How would I know what ends up canceled out and what the final chemical formula ends up being so I can write out the ICE chart? What is the process in finding that final formula so I can use it for future problems? Thank you!
finding the chemical formula for salt solutions
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Re: finding the chemical formula for salt solutions
Hi Katie! Here are the general formulas I use for weak acids and weak bases:
HA(aq) + H2O(l) <--> H3O+(aq) + A-(aq)
In this case, the reactant is a weak acid HA, and donates its hydrogen ion.
B(aq) + H2O(l) <--> BH+(aq) + OH-(aq)
In this case, the reactant is a weak base B, and gains a hydrogen ion from water.
I cancel out the ions/compounds that dissolve fully in water/solvent, such as those that make up strong acids and strong bases like Na+ and Cl- ions.
For more clarification, here is how I set up the formula for Question 7:
You can see that I cancelled out the Na+ ions because it dissolves fully in water.
Hope this helps!
HA(aq) + H2O(l) <--> H3O+(aq) + A-(aq)
In this case, the reactant is a weak acid HA, and donates its hydrogen ion.
B(aq) + H2O(l) <--> BH+(aq) + OH-(aq)
In this case, the reactant is a weak base B, and gains a hydrogen ion from water.
I cancel out the ions/compounds that dissolve fully in water/solvent, such as those that make up strong acids and strong bases like Na+ and Cl- ions.
For more clarification, here is how I set up the formula for Question 7:
You can see that I cancelled out the Na+ ions because it dissolves fully in water.
Hope this helps!
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- Posts: 36
- Joined: Mon Jan 09, 2023 8:51 am
Re: finding the chemical formula for salt solutions
Thank you! This makes so much sense and it was really helpful :]
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