G. Chem question

ehrughan
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Joined: Tue Apr 24, 2018 3:00 pm

G. Chem question

Postby ehrughan » Fri May 11, 2018 8:55 pm

Hey there!

In G. chem Chapter 3 passage (p.58), i'm confused as to how to arrive to the answer for question 5. The answer is CaSO4, but I don't see how they got to that given the information in the passage, and the answer key isn't bearing much help. They mention we should expect to see Ca and/or sulfate, how did they get sulfate when all we know is that one of the reactants was Ca(NO3)2 "calcium nitrate".Thanks!
NS_Tutor_Katelyn
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Re: G. Chem question

Postby NS_Tutor_Katelyn » Thu Jun 07, 2018 4:47 pm

ehrughan wrote:Hey there!

In G. chem Chapter 3 passage (p.58), i'm confused as to how to arrive to the answer for question 5. The answer is CaSO4, but I don't see how they got to that given the information in the passage, and the answer key isn't bearing much help. They mention we should expect to see Ca and/or sulfate, how did they get sulfate when all we know is that one of the reactants was Ca(NO3)2 "calcium nitrate".Thanks!


We know from the passage that the unknown solution contains sodium sulfate (the paragraph after table 1), and that it reacted with calcium nitrate. We also know that the sodium sulfate did not react with any of the other solutions (all of which contained nitrate). This tells us that the precipitate consists of calcium, but not nitrate (since if the precipitation contained nitrate, any of the other solutions should have reacted as well). Therefore, we know that the precipitate must be composed of calcium and sulfate. Let me know if that clears it up for you!

-Kate
Katelyn Sawyer
Senior Tutor
katelyn@nextsteptestprep.com

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