Section Bank C/P #73. Possible mistake?

[coffee-doc]

So I got the question right, but I think I have been messed up with the concept of millimoles since like AP Chem from years ago. The solution states that

'10 mM of MgCl2' indicates that there are 10^-2 moles per liter. Is this is a mistake on AAMC's part because shouldn't it be 10^-3? Or am I missing something.

For some reason, something from AP Chem is kicking in that's saying that milli means 10^-3 with the exception of millimoles that are 10^-2

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[Wolfpack93]

So I got the question right, but I think I have been messed up with the concept of millimoles since like AP Chem from years ago. The solution states that

'10 mM of MgCl2' indicates that there are 10^-2 moles per liter. Is this is a mistake on AAMC's part because shouldn't it be 10^-3? Or am I missing something.

For some reason, something from AP Chem is kicking in that's saying that milli means 10^-3 with the exception of millimoles that are 10^-2

Why would it be 1x10^-2?

 

[Wolfpack93]

Sorry I wasn't understanding because I just read the question. Must have been given that there were 10mM in the passage I'm assuming. It's 1x10^-2 because its 10mM. If it were 1mM it would be 1x10^-3.

 

[aldol16]

'10 mM of MgCl2' indicates that there are 10^-2 moles per liter. Is this is a mistake on AAMC's part because shouldn't it be 10^-3? Or am I missing something.

10 mM means there are 10 x 10^-3 mM, or 1 x 10^-2. You should be comfortable with using scientific notation and putting numbers into/taking numbers out of exponents because that will be important for simplifying math during the exam.

 

[coffee-doc]

ah okay nvm

 

[stressedandpremed]

Hi,

Sorry for reviving this thread, but when they say "volume of reaction solution" why is that only volume of MgCl2 when there are two compounds in the solution?

This question took me a lot longer than it should have because I found ul of MgCl2 and wasn't sure if I should do a molar ratio (300 mM KCl and 10 mM MgCl2) to figure out the volume of the KCl, and then add those up. I chose A (500 ul) only because the answer I got when I tried to find the KCl volume and then add that back to 500 ul wasn't an option.

 

[hapadays]

Hi,

Sorry for reviving this thread, but when they say "volume of reaction solution" why is that only volume of MgCl2 when there are two compounds in the solution?

This question took me a lot longer than it should have because I found ul of MgCl2 and wasn't sure if I should do a molar ratio (300 mM KCl and 10 mM MgCl2) to figure out the volume of the KCl, and then add those up. I chose A (500 ul) only because the answer I got when I tried to find the KCl volume and then add that back to 500 ul wasn't an option.

Can someone shed some light on this? I got this correct, but the language of the question is off. It asks for the "volume of the reaction solution" which would mean 10mM MgCl2 + *either* 100mM Kcl or 300mM KCl, right? Either two of those situations is what the entire reaction solution consists of. However, given what the right answer is, the question should have asked for the volume of the MgCl2 portion of the reaction solution *alone* that was added. Is this one of those questions where it's implied? If so, why?