Help in Chemistry

Thread created on 06:05:20  25/03/21 (6 months ago)Last replied 04:34:15  12/04/21 (6 months ago)
Well first of all good day to everyone I'm a student and because our teachers didn't tellus how to do this I want my fellow torn players to help me if possible.
P. S. Please give me the answer till 8:00 25/03/21 torn time
PROBLEM NO. 1 (Mole fraction): A solution contains two compounds (X and Y). Compound X has 2.88 x 10 23 molecules and compound Y has 4.54 x 10 23 molecules. Find for the mole fractions and molecular weights of compounds X and Y if the solution weighs 54.5 grams.
GIVEN:
UNKNOWN:
SOLUTION/S:
PROBLEM NO. 2 (Mass percentage): How many grams of a solution that is 12.5 % by mass AgNO3 would contain 0.40 moles of AgNO3?
GIVEN:
UNKNOWN:
SOLUTION/S:
PROBLEM NO. 3 (Massvolume percentage): Calculate the mass/volume percent of a solution made of by dissolving 4.20 grams of NaCl in water to make 12.21 grams of saline solution with a density of 1.024 g/ml.
GIVEN:
UNKNOWN:
SOLUTION/S: 

Posted on 18:18:19  05/04/21 (6 months ago)Post link copied to clipboard Copy post link
I understand that it's too late for the solution. Have you succeeded in this?


Posted on 18:19:34  05/04/21 (6 months ago)Post link copied to clipboard Copy post link
BTW the first question have no answer, since we don't know the weight of the molecules ...


Posted on 05:08:45  08/04/21 (6 months ago)Post link copied to clipboard Copy post link
NOPE I didn't succeed in answering this and my prof still didn't explain it


Posted on 17:00:34  08/04/21 (6 months ago)Post link copied to clipboard Copy post link
A mole of a certain compound always contains 6.023 x 10 23 molecules (avogadro's number), this way if we divide the amount of molecules in the compound (X and Y) by that number we can obtain the number of moles of that certain compund. With that we can obtain the molar fraction by dividing the amount of moles of the compound by the total of moles present on the solution (which is the sum of both moles' compounds).
We can calculate the amount of each molecular weight by first dividing the total weight of the solution by the total amount of moles and then multiplying by the previously calculated molar fraction of each compound (assuming you don't use percentages).
Hope this helps. 

Posted on 10:47:31  09/04/21 (6 months ago)Post link copied to clipboard Copy post link
PROBLEM NO. 2 (Mass percentage): How many grams of a solution that is 12.5 % by mass AgNO3 would contain 0.40 moles of AgNO3?
Mass of 0.4 moles AgNO3 must be equals to 12.5%. After you got mass of 0.4 moles AgNO3, just find how many grams of the solution. It equals to (100/12.5) x mass of 0.4 moles AgNO3Last edited by Sokita on 10:48:03  09/04/21 

Posted on 06:16:45  10/04/21 (6 months ago)Post link copied to clipboard Copy post link
I'm assuming it's too late to point this out, but since the mole is the standard unit, you need to find how Many moles you have of a solution, then convert these moles into your needed amount. When comparing two different molecules in a sample and finding their relative proportions, you do the same thing.


Posted on 04:34:15  12/04/21 (6 months ago)Post link copied to clipboard Copy post link
Thanks for giving me the answer guys
