Question

A pair of 100mL samples of water are taken from a well bored into a large underground salt NaCl deposit. Sample #1 is from the top of the well, and is initially at 32°C. Sample #2 is from a depth of 50.m, and is initially at 42°C. Both samples are allowed to come to room temperature (20.°C) and 1atm pressure. An NaCl precipitate is seen to form in Sample #1.
a. A bigger mass of NaCl precipitate will form in Sample
b. A smaller mass of NaCl precipitate will form in Sample
c. The same mass of NaCl precipitate will form in Sample #2.
d. No, precipitate will form in Sample #2.
e. I need more information to predict whether and how much precipitate will form in Sample #2.

Answer 1

Answer:

The correct is A (A bigger mass of NaCl precipitate will form in Sample #2)

Explanation:

From the question we are told that

The volume of each sample is $V_1 = V_2-V= 250 mL$

The temperature of sample one is $T_1 = 32^oC$

The temperature of sample two is $T_2 = 42^oC$

The depth from where sample two is gotten is $d = 50 \ m$

The final temperature of the samples is $T_f = 20^oC$

The final pressure is $P_f = 1atm$

From the data given we see that the initial temperature of sample 2 is more than sample 1 so more NaCl will be dissolved in 2

Now when both samples are brought to $T_f$ there will be a greater decrease in temperature in sample 2 than in sample 1 so more precipitate of NaCl will be formed in sample 2 than in sample one