DAT BC GChem Solubility

[emminent]

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A 100mL 1M solution of calcium nitrate Ca(NO3)2 is mixed with 500 mL of 1M NaOH. The resulting mixture shows no precipitate – what is the most likely reason for this?

Answer is temperature causes the change. I get that Na and nitrate are completely soluble but isn't Ca(OH)2 a strong base which completely dissociates? and that Ca is a group one atom?

 

[bamtori]

@emminent aren't you done studying for the DAT?

 

[emminent]

@emminent aren't you done studying for the DAT?

No postponed it to the 15th 🙁 Work schedule messed me up so I didn't feel ready. Just doing BC and only did the RC for qvault lol. I'll keep you updated by Friday.

 

[emminent]

Btw bam, isn't Ca(OH)2 soluble?

 

[dawg289]

At room temperature, Ca(OH)2 is normally insoluble. However, the solubility of Ca(OH)2 is quantified by the Ksp, which is temperature dependent. By increasing the temperature, you can decrease the Ksp of Ca(OH)2 and thus prevent any precipitant from forming.

 

[emminent]

At room temperature, Ca(OH)2 is normally soluble. However, the solubility of Ca(OH)2 is quantified by the Ksp, which is temperature dependent. By increasing the temperature, you can decrease the Ksp of Ca(OH)2 and thus prevent any precipitant from forming.

Interesting... thanks dude.

 

[dawg289]

I meant insoluble, not soluble, sorry.

 

[TheEpicFruitCake]

At room temperature, Ca(OH)2 is normally insoluble. However, the solubility of Ca(OH)2 is quantified by the Ksp, which is temperature dependent. By increasing the temperature, you can decrease the Ksp of Ca(OH)2 and thus prevent any precipitant from forming.

wait, doesn't a higher ksp = more soluble? So increasing temperature increases solubility and ksp. right?

 

[Weakfart]

Interesting... thanks dude.

Also, hydroxides are normally insoluble except when combined with a soluble cation like a group 1 cation, this one is a group 2.

 

[dawg289]

wait, doesn't a higher ksp = more soluble? So increasing temperature increases solubility and ksp. right?

Yes, higher Ksp means more soluble. Increasing temperature increases Ksp, which explains why solubility increases.