Hello! I'm hoping you can please help me with this! I left my book at school (I thought I'd left it in my backpack all day to bring home), and I'm in desperate need of your help because I have a test tomorrow.
"Answer the following questions, which refer to the 100mL samples of aqueous solutions at 25 degrees celcius in the stoppered flasks shown below.
There are pictures of four flasks which have 0.10 M under each of them also with the compound names... NaF, MgCl2, C2H5OH, CH3COOH
a. Which solution has the lowest electrical conductivity? Explain.
b. Which has the lowest freezing point? Explain.
c. Above which solution is the pressure of water vapor the greatest? Explain."
Your help will be GREATLY appreciated!!
Do you want us to simply give you the answers to these three problems? That won't help you much on an exam tomorrow. I will give you some hints and we can go from there.
a. Which compounds ionize completely? Which ionize partially? Which don't ionize at all. Since electrical conductivity is based on the number of ions in solution, then the one(s) that don't ionize at all will be the one(s) that has/have the least electrical conductivity.
b. Do you remember studying the molal freezing point constant.
Delta T = iKfm
where delta T is the amount the freezing point is lowered. i is a factor that is 1 for non-ionized materials, 2 for two ions, 3 for 3 ions, 4 for 4 ions, etc. Since we have the same solvent and the molarities are the same, then Kf and m are the same so it all comes down to knowing which ones ionize and into how many pieces.
c. Remember that the vapor pressure is lowered when a non-volatile solute is placed in a volatile solvent. You should be able to do this one after you have done a and b. I hope this helps. get you started.
Oh I didn't expect the answers, just some help! That DEFINITELY helps! Thanks you so much! I appreciate your help!
3 answers