June 07, 2020, 03:09:04 AM
Forum Rules: Read This Before Posting

### Topic: Help Urgently needed with Molarity/Dilutions/Solution Stoichiometry  (Read 146 times)

0 Members and 1 Guest are viewing this topic.

#### greenfieldhelp

• Very New Member
• Posts: 2
• Mole Snacks: +0/-0
##### Help Urgently needed with Molarity/Dilutions/Solution Stoichiometry
« on: May 22, 2020, 04:14:13 AM »
Hello. In my chem class, we have a big assignment that's due tomorrow night, and I'm super stuck on the last problem.

On the worksheet, there are three problems (one for each), and for each problem, you're supposed to define the topic, show step-by-step how to solve it, and then solve a problem. For the most part, I feel like I understand Molarity and Dilutions (the first two problems), but Solution Stoichiometry (the third) has gotten me stuck. I've tried my best, and I still don't know what to do. If someone could please help me solve the last problem, I would be eternally grateful. If someone could also check the previous two to make sure I did everything right, that would be amazing! Feel free to leave actual comments on the document, or just leave a comment below. Please someone, I am lost, and this is quite a large portion of my grade.

#### AWK

• Retired Staff
• Sr. Member
• Posts: 7331
• Mole Snacks: +515/-86
• Gender:
##### Re: Help Urgently needed with Molarity/Dilutions/Solution Stoichiometry
« Reply #1 on: May 22, 2020, 11:03:26 AM »
B. There can't be good answers to stupid questions. For the polarity of NCl3 and SiI4, check Wikipedia. All compounds in question B react with water, so it's difficult to talk about solubility. NCl3 reacts relatively slowly, the other two very quickly. The solubility of Mg(OH)2 in water is a few mg per liter, so you won't get a 0.75 M solution under any circumstances.
G III. - when diluting the solution, the concentration decreases, but you did not throw away the moles of the substance in the trash.
H II. - simple stoichiometry 0.120 mol BaCl2 ==> 0.120 mol BaSO4 - just calculate the mass.
H III. You have a known amount of moles of chloride ions and you know the concentration and volume of iron (III) sulfate, so it's easy to calculate the molar concentration in the volume of 200 mL. You have precipitated virtually quantitatively barium and sulfate ions.

If significant numbers are important, check all responses for this.
AWK