blackhole123

How would your unknowns calculated molar mass be affected if you spilled some of it after weighing, but before you put it in the solvent? Ok, so less solute means less depression, so delta T is smaller. By this equation: deltaT=Kf x m that would mean calculated molality would be less, which would give you less calculated moles, which would give you a higher molar mass since you are still using the same mass value in the molar mass calculation. So that means that a higher molar mass depresses the freezing point less? I thought it was the other way around. Am I missing something here?

The problem is, its difficult to go from a trend like that to y=1/x Sure, once you point it out to them they see why it works, but its hard for them to recognize it on their own. I think I may be overestimating the diffcutlty of potential problems. Most of the time you will not have to extend the table out to arbitrarily large numbers, and you can look at the trend to get it without finding an equation. I guess I was just wondering if I was forgetting some algebraic method of determining the equation of a line from a table of values.

Never mind, delete this please.

I was helping my little cousin with his math hw, and one of the questions was predicting points on a graph. They gave you a table: X | Y .5 | 2 1 | 1 2 | .5 4 |.25 5 | ? 10| ? Now, obviously this is just y=1/x just from looking at it. It's easy to see what happens to Y as you increase X. But I didn't know how to explain it to him algebraically if he gets a similar problem on a test, and he is not able to see trends in his head like more experienced people can. I also don't know if they are going to give him unknown values that are unrealistic to every number out to. This is embarrassing, but how do I explain this to him?

...from a chemical engineer if I just get a degree in chemistry instead? I saw that chemical engineers are the highest paid college major, and it got me wondering. http://education-portal.com/articles/Top_10_Paying_College_Majors.html Of course I will still be pursuing chemistry and not engineering, but it would be interesting to know. I know the type of job that someone with a chemistry degree gets compared to a chemical engineer differs, but how would this affect pay? Lets say I get a BS in chemistry, go to grad school and get a PhD. Now what? For chem engineers job choice is obvious, but what does a chemist do? If I go into industry won't I be at a disadvantage to the engineers? Will I have a harder time finding a job because I am going for pure chemistry?

Right, thats my problem, I can't figure out how to tack that on. I'm sure its not difficult once I get it, I just don't know how to get it.

Don't you have to take into account the added volume of the solution of the antifreeze? You aren't adding pure ethylene glycol, you are adding a solution of it, so if you act calculate it without taking that into account your calculated value will be lower than what you actually need to add. I believe the antifreeze comes out to be 17.833m using the density.

How many liters of antifreeze ethylene glycol (C2H6O2, density 1.11 g/ml) would you add to a car radiator containing 6.5L of water if the coldest winter temperature in your area is -20C? So I figured I can use the freezing point depression equation to figure out what the molality of the resulting solution must be if the freezing point of water is depressed 20 degrees C. I got 10.75m. Now I don't know how to figure out how much of the solution to add to the 6.5L of water to make it this molality. Some sort of ratio? I'm lost.

So far whenever I look for some online I don't know if they are the right kind. I've gotten a lot of results for construction goggles and such. I figure I am going to be in lab a LOT throughout college so I should get a really good comfortable pair that doesn't leave red lines on my face. Right now I am still using my $5 pair. So, anyone know a good website or have a suggestion for me?

A poster at some other forums I frequent. Here is his "scientific" response to this article (http://www.esnips.com/doc/a64c537c-356c-4ce7-b403-a4db06721ff9/Parker.JClim.2006), which I posted along with an IPCC report that referenced it. I have no reason to believe anything that IPCC says. they are crock and sham just like the guy in charge of it. I see you ignored the article again. No one should believe anything come out of the IPCC. It isn't science it is an independant power grab. the only science they are pushing is the one that lines their pockets with more carbon credit deals. I didn't look at another article on the same thing because i figured it was just a carbon trading company that got caught doing something. I had no idea that the chairman of the IPCC was in on it. did you know that the the guy in charge of the IPCC helped develop technology so that oil companies could get the last bit of oil out of reserves that they couldn't before? ol yea by the way the guy in charge of the IPCC and that speared that 2007 report isn't a scientist. so he has 0 credibility on anything that he authorizes, and you make the claims that the sources i use aren't science. ol the hypocrasy is amazing.

Debating global warming, their arguments basically boil down to this: - There is no proof for global warming. - Any scientist who believes in global warming is just being bullied into it - Most peer reviewed papers have made up data in them, because scientists just want more funding Every time I post a counterargument I am simply amazed at their skill to totally ignore and twist things. This seems to be the bane of my existence; do you argue with these types of people knowing that their ignorance will never go away, or do you just accept that you can't change their mind even though it grinds your gears to even think about it?

I guess I meant to say that I know about MSDS sheets. We never read them before working with anything. It's chem 105. I just looked it up and it said to rinse for 15 minutes. It still looks fine, should I do this?

Ok thanks, I'm feeling a lot better about the situation now. If something like this ever happens again I'm telling my lab instructor, it was stupid of me to not report it.

Yeah my goggles are pretty cheap. I am planning on buying new ones. I didn't really think to use the eyewashing station. Honestly, if felt like when you get a peace of dust in your eye or something. And then it went away. If it had been acid, would it have made my eye really red and burn or something? It's been a couple hours now and I feel fine. I am familiar with MSDS of my chemicals, yes.

Today I was weighing some sulfamic acid and there was some on the scale and not on the weighing paper so I blew at it. I felt a little spec of something hit my eye (I was wearing goggles, there was a little opening on the side). It may or may not have been the sulfamic acid. My eye feels fine, looks fine, I can see fine, and I didn't think anything of it in lab, but now that I'm home I just started to worry. Again, everything feels fine I just started thinking about it and I have this habit of worrying myself. I shouldn't be worried right? I'm not going to wake up blind tomorrow?

I learned that electron stability depends on the Zeff value because it takes into account shielding. However, the Zeff of, say a 2s He electron is less than the Zeff of a 2p Carbon electron. BUT the He electron is obviously a lot more stable, as it is a noble gas and doesn't bond easily. I know that the He electron is closer to the nucleus where the positive charge is, but the total charge on it is STILL lower than the charge felt by a 2p carbon electron. It seems like it shouldn't matter how close it is, because in the end it is effected by a lower charge. Would I be right in saying then that the fact that the He has a full 2s shell which is the lowest energy state is more important in terms of stability than the fact that its Zeff is lower? Or does it really just have to do with how close it is to the nucleus?

The question gave me the temperature and pressure of water vapor. I need to figure out the distance (in nanometers) between each molecule of gas assuming it is an ideal gas. It gives me the diameter of a water molecule (in nanometers). I figured out the density of the water vapor in molecules/liter. Now I'm stuck. I think I could figure out how much space the total amount of molecules takes up in nm^3 in one liter, and also the total space of one liter in nm^3, but I'm not sure if that is relevant. I just don't know how to proceed, this is a brain buster. I know the the number of molecules and volume, so I know it's possible to calculate, but I don't know what method I would use to do such a thing.

Alright thanks. One more easy question. I have recorded in my lab notes that when I added CuSO4 to water (anhydrous, white powder), it turned blue. But I think when you add CuSO4(s) to water it just makes CuSO4(aq). I know the pentahydrate form is blue. Why did my solid turn blue? Is the pentahydrate forming? Also, when I add CuSO4 5H20(aq) to solid zinc what does it form, ZnSO4 or ZnSO4 5H20?

1. (bunch of filler info about barium sulfate). Given the following starting compounds, write for each compound a balanced total ionic equation and a balanced net ionic equation to prepare BaSO4: Ba(OH)2, BaCl2, BaCO3. If the the rxn occurs in more than one step then write the rxn as a series of sequential reactions. Identify the type of each reaction. For this one do I just add some sort of soluble sulfate compound that reacts with the starter compound to produce an insoluble precipitate? I'm guessing the first one is some sort of acid. Would you add H2SO4 and get (for the molecular equations, I know how to do ionic equations thats not the problem): Ba(OH)2(aq)+ H2SO4(aq) --> BaSO4(s) + 2H2O(l) the next one, BaCl2(aq)+ Na2SO4(aq) --> BaSO4(s) + 2NaCl and BaCO3(aq)+ K2SO4(aq) --> BaSO4(s)+ K2CO3 Is this right? I think I solved this one too, look at edit #2. 2. Describe how you would separate the cations or anions in the following aqueous solutions by forming a precipitate. Include your logic with your description. a) NaNO3 and Ba(NO3)2 (separate Na^+ from Ba^2+) It goes from a-e but I just need to know how to do and I can do the rest. I'm confused when it talks about separating Na from Ba. They are only together in the sense that soluble compounds in a solution are ions floating around. So do you add a compound that would form an insoluble precipitate or something like in the first problem? EDIT: I think I've figured out what to do in #2. You need to add something that will precipitate Na+ out but not Ba2+, then filter and do the same for Ba2+. EDIT 2: Looked some more and I got that barium sulfates are insoluble (I just did a whole problem on it, DUH!) So if I add a random sulfate like K2SO4 it will make BaSO4 ppt but Na will still be in there? Does making a new compound that is a ppt count as separating them? Does NaNO3 change at all?

Alright and one more question while I work on that one. How would I determine if an unknown acid I was given is weak or strong? I have NaOH and NaCl to work with. Some sort of titration?

I'm having trouble balancing that. I guess thats what I have to do since it can be balanced an infinite amount of ways, is assume one number and then go from there. But I'm having trouble even after assuming 20 molecules of gas.

In a car engine, gasoline (represented by C8H18) does not burn completely, and some CO forms along with CO2 and H20. If 5.0% of the gasoline forms CO: A) What is the ratio of CO2 to CO molecules in the exhaust? B) What is the mass ratio of CO2 to CO? C) What percentage of the gasoline must form CO for the mass ratio of CO2 to CO to be exactly 1/1? I literally have no clue what to do with this problem. Can someone point me in the right direction? All I have is the unbalanced equation: C8H18+ O2 --> CO2+H20+CO

A friend I was debating claims that nuclear power is THE answer, and that other countries (not US), use a lot more than us. He then claimed that Canada stores ALL it's nuclear waste in one place the size of a football field. I find this VERY hard to believe. Is he wrong about this? Why are most people opposed to nuclear power (including my science professors), is it the waste or the risk of a meltdown?

The average concentrations of bromine in seawater (d=1.024g/mL) and the Dead Sea (d=1.22g/mL) are .065g/L and .50g/L, respectively. What is the mass ratio of bromine in the dead sea to that in seawater? I have no clue what to do here. The answer is 7.7/1 but I can't get there. Is this testing significant figures? EDIT: Wow was I overthinking this. Just divide the two concentrations to get 7.69 which is 7.7..... don't I feel foolish.