Dat bootcamp gen chem test 1 #30

[myshinyteethandme]

hey guys: the question reads; 30. 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?

in the explanation it says; the product formed, calcium hydroxide Ca(OH)2 is only very slightly soluble in water, but you would expect to see some precipitate given the amounts in the question. Since temperature increases solubility, answer is the only plausible explanation. If the temperature was very low, we would expect to see product.

Can anyone elaborate and what they mean by the "amounts given in the question" and how it would affect seeing a precipitate? thanks !!!!

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[TheEpicFruitCake]

The amount in the question is 100mL of 1M calcium nitrate and 500mL of 1M NaOH. You don't care about the actual solubility of Ca(OH)2 because you should know that it is insoluble from your solubility rules that should be memorized. It's a conceptual question, screw the numbers (it would only matter if it was really really dilute, which it's not). You seem to be asking a lot of questions. Might I suggest Chad's Videos? Everything you've asked is covered by him.

 

[myshinyteethandme]

Do you know where i can get those videos?

 

[emminent]

Do you know where i can get those videos?

http://www.coursesaver.com/videos/DAT/

 

[TheEpicFruitCake]

Or this lol If you're gonna sign up anyways
http://www.coursesaver.com/index.php?referrerid=40892

 

[dontbescared]

The amount in the question is 100mL of 1M calcium nitrate and 500mL of 1M NaOH. You don't care about the actual solubility of Ca(OH)2 because you should know that it is insoluble from your solubility rules that should be memorized. It's a conceptual question, screw the numbers (it would only matter if it was really really dilute, which it's not). You seem to be asking a lot of questions. Might I suggest Chad's Videos? Everything you've asked is covered by him.

Sorry, where do you get that Ca(OH)2 is insoluble? From my notes I see that it is actually soluble..

 

[TheEpicFruitCake]

Sorry, where do you get that Ca(OH)2 is insoluble? From my notes I see that it is actually soluble..

Google solubility rules. If your notes say alkaline earth metals with hydroxide are soluble then they are incorrect (except Ba2+). Now they don't have a solubility of like 10^-50 or something like that, but we consider them to be "not soluble." If you want to be anal about it then it's slightly soluble. But even with that the question remains the same. It's a theory question rather than a "crunch the numbers" because they don't give you ksp.

Solubility is relative so yes Ca(OH)2 is soluble to some extent, but then you can make the argument that EVERYTHING is soluble to some extent.