## FL#1 in Chem/Phy Q1

jumpinfeet
Posts: 17
Joined: Tue May 09, 2017 11:12 am

### FL#1 in Chem/Phy Q1

On this first question, I am a little confused by Figure 1. I feel like it is giving me NaCl at 35 g per 100 g of H2O at 60 C. I use it to calculate and I get the wrong answer. I know that the first paragraph states that it is 3.5%, which calculates to the right answer. What is the clue to tell me to not use Figure 1? Thanks for the help!
NS_Tutor_Andrew
Posts: 520
Joined: Mon May 23, 2016 1:47 pm

### Re: FL#1 in Chem/Phy Q1

Hi jumpinfeet,

Thanks for the question! Figure 1 gives you information about solubility, which corresponds to the maximum possible amount of the solute that could be dissolved before creating a saturated solution. However, the question is not asking about what the molarity of a saturated solution of NaCl and water would be, it's asking about what the actual molarity of ocean water is. This requires you to combine the density info given in the question with the info from paragraph one saying that ocean water is 3.5% NaCl by mass.

Hope this was helpful! The bigger-picture lesson here, I think, is to be super careful about whether the information you're pulling from a figure or table is precisely what you need to answer the question. This is a pretty common danger in MCAT questions, which is why my #1 piece of advice to students about figure/data interpretation is to carefully read the figure/table legends and axes in order to be absolutely sure of what the quantitative data means.
Andrew D.
Content Manager, Next Step Test Prep.
heatfan
Posts: 26
Joined: Sun Apr 30, 2017 12:34 pm

### Re: FL#1 in Chem/Phy Q1

Hello, I just wanted to know what the significance of the 3.5 % to figure out the calculation? I missed that detail when I was trying figure out the calculation on the exam. Thanks.
NS_Tutor_Katelyn