Chem Definition and 424 Threads

Urgent need Help on Chem... (average velocity, Thermochemistry, ionization energy) 1.) The average velocity of Cl(2) molecules is 2.50 x 10^3 m/sec at a temp of 25 C therefore the average velocity of helium atoms is ?? [ i got the answer 1.05 x 10^4 m/Sec] but I am not sure 2.) A gas is...

Homework Statement Discuss in detail (with the use of chemistry examples) whether the mole concept is fundamental and essential to chemistry, or merely a convenience concept. The bottom line question is "Could we do chemistry without the mole concept?" Homework Equations The...

Homework Statement I need to find net ionic equations for: -Fe(NO3)3 + NH3 -Cr(NO3)3 + NH3 -Cu(NO3)2 + NH3 -AgNO3 + NH3 -Cr(OH)3 + NaOH -Fe(OH)3 +NaOH and a whole bunch of other reactions. I have no problem with writing the balanced equations but I get a little stuck on breaking things...

How can you know if a complex ion has an optical isomer or not? I understand that it's when the mirror image can't be superimposed but am having trouble recognizing it. For example, take [Co(NH3)4F2]+. Does this have an optical isomer or just cis/trans?

Hello, I am a physics undergrad...getting ready for my final semester this summer. I have to take a chemistry class (actually, anything above a first General Chemistry class). It just so happens that the ONLY such Chem class they offer (small school) during my final semester is Organic...

1. Homework Statement The relative abundance of uranium isotopes in today’s Earth crustal material is: 99.2745% 238U 0.7196% 235U 0.0055% 234U What were the relative abundances when the Earth was formed 4.6x109 years ago? 2. Homework Equations t = age = 1/lambda * ln(N/No) N...

Homework Statement What percentage of the original Ag+ remains in solution when 175 mL of 0.0208 M AgNO3 is added to 250 mL 0.0380 M K2CrO4? Homework Equations The Attempt at a Solution I found the initial amont of CrO4 and Ag and put that into the equilbrium expression of...

Since Benedict's test is testing for the presence of a reducing agent (in the form of a carbohydrate), would that not mean it would give a false positive if acid was present (i.e. is acid not considered to be a reducing agent, it being a proton donor)?

Hi, I am supposed to design 2 experiments for my senior year Chem class. Right now I cannot think of anything that is interesting, relatively advanced but at the same time at a high school level (its only a design lab so I can include advanced equipments). Topics that interest me the...

Which of the following is a redox reaction? A. TiCl4(g) + 2 Mg(l) D Ti(s) + 2 MgCl2(l) B. NH3(g) + CO2(g) + H2O(l) NH4HCO3(aq) C. NaCl(s) + NaHSO4(s) D HCl(g) + Na2SO4(s) D. NaOH(aq) + H3PO4(aq) NaH2PO4(aq) + H2O(l) E. None of the above Is it A? Also another q. The primary reason for...

If you don't have a B. Eng. (and are not a certified engineer): Does it make sense to do an M. Eng.? What is the difference between the kind of jobs you can get with an M. Sc. in chemistry, and an M. A. Sc. or M. Eng. in chemical engineering? What about an M. Sc. plus MBA? I am one...

Right now, I'm torn between 4 majors, 2 of which are fairly similar (chem and chem engineering). My main questions is out of those 4, which one do you think will offer the best career options with just a B.S. Right now I'm not planning on a masters or PhD program. A few things about me...

Homework Statement A gas has a Henry's law constant of 0.150 M/atm. How much water would be needed to completely dissolve 1.49 L of the gas at a pressure of 720 torr and temp of 14 C.Homework Equations m = amount solute (in mol)/mass solvent(in kg) M = amount solute (in mol)/volume solution...

Homework Statement For the equilibrium PCl5 <---> PCl3 + Cl2, all gases, Keq = 4.16e-2. The equilibrium concentration of PCl5 is 1.0 M, and both PCl3 and Cl2 are 0.204 M. If the volume of this closed system is doubled, what are the concentrations of each gas when a new equilibrium is reached...

I just graduated with a MSc degree (4-year program) in Applied Chemistry from University of Karachi, Pakistan. I am interested in pursuing a masters degree in Chemical Engineering. I have 63% in my undergrad degree, the top most student has 71%. I rank about 20th among 60 students.And I have...

Homework Statement Write a detailed mechanism for the following reaction: Attached picture Homework Equations N/A The Attempt at a Solution Okay, I know this is PART of the mechanism for the oxidation of a glycol by periodic acid which causes cleavage of the C-C bond between the...

Hi I have two questions grade 11 chem questions that I don't know how to do. HELP PLEASE! Q1: Tetraethyl( Pb(C2H5)4 ) lead was added to gasoline up to 2.0ml per 3.8L of gasoline. a)Calculate the mass of Tetraethyl lead in the total amount of gasoline that you use for this trip (31.2 L of...

Homework Statement 800ml sample of 2.00 molar formic acid HCOOH (or HA) ismixed with 200ml of a 4.80 molar NaOH. Calculate the [H3O+] of the resulting solution. Homework Equations (for buffers) pH=pKa-log(HA/A-) Ka for formic acid is 1.8x10-4 pH=14-pOH [H+]=(1.00x10-14)/([OH-) The...

Hey guys, does anyone have a strong link for a Virtual Chem Lab for General Chemistry labs? It can be online or downloadable. Thanks

All relevant data is attached in a .jpeg. Ultimately, I have 4 equations with 6 unknowns. I found the correct answer through a chem calculator, but I'm wondering how it computed the balanced equation. Any insight much appreciated! Jeff

Homework Statement Which of the following solid substances can be liquefied simply by increasing the pressure suffciently? ice (H2O) diamond (C) dry ice (CO2) sulfur (S) graphite (C) Which of the following substances cannot be liquified at 1 atm pressure? nitrogen (N2) helium (He)...

Homework Statement Find the mg of Fe in vitamin pill. Vitamin pill was dissolved in 25mL HCl which was then diluted to 250mL with water in flask. 25mL of that solution was then diluted to 100mL in another flask. 10mL of the second was diluted to 100mL in another flask. Absorbance of the last...

Homework Statement Al3+ N3- Li+ Au+ Sr2+ Mn2+ Tl+ Br - Homework Equations The Attempt at a Solution no clue, the positives and negatives are messing me up

Homework Statement I need to calculate the temperature and pressure at the triple point. natural log of pressure of the liquid/solid: lnp(solid)= 29.411-(5893.5K/T) lnp(liquid)=22.254-(3479.9K/T). The compound is uranium hexafluoride, MW= 352.02. I do not believe the actual molecule matters...

What is the bond order of CO+ I don't even understand how do this because C does not obey the octet rule in this case. Can anyone help?

1Q. Explain why you would expect a BeF2 molecule to be linear but a SF2 molecule to be angular? A. Beryllium fluoride would be linear because each of the two valence electrons in a beryllium atom is shared with an electron from a fluorine atom. Using the valence electron-pair repulsion theory...

Homework Statement What is the total number of atoms in the molecules? NH3 - 2.5 mole Homework Equations Would you multiply the number of atoms in NH3 by Avogadro constant to find the number of atoms? (4 atoms)(6.02*10^23) =answer Or would you multiply the number of moles by Avogadro...

i might get confusing cause i don't understand this very much but here is the copy of my lab i need help with #1 & 6 of the POST-ALAYSIS here is the word doc. of my lab http://courses.digitaldapp.org/documents/Inquiry%20Lab%20-%20Experiment%2003%20-%20Composition%20of%20a%20Hydrate.doc...

Homework Statement Write the balanced net ionic equations for the reactions, if any that occur between: NiS(s) & HCl(aq) My attempt: NiS(s) + 2HCl(aq) -> NiCl2(aq) + H2S(s) NiS(s) + 2H + 2CL -> Ni(aq) + 2CL + H2S(s) NiS(s) + 2H(aq) -> Ni(aq) + H2S(s) My real question is...

H2SO4 (aq) + 2HI (aq) --> SO2 (g) + I2 (s) + 2H2O (l) Indicate the oxidizing and reducing agents. ----------------------------------------------------- I started by assigning oxidation numbers to all the atoms: H=+1 O=-2 S=+6 to +4 I=-2 to 0 I think H2SO4 is the reducing agent and...

An instrument can detect 9450 photons of light of wavelength of 8.065 × 10^-8 m. What is the minimum amount of energy in J to which the instrument is sensitive? Express answer in scientific notation.. i have tried to use the e = (planck's constant) ( speed of light ) / (wavelenghth) but i am...

Hi This is my first science subject ever, and I am having difficulties so I would love to have all the help I can get please. My assignment is about Lewis structures and empirical formula for the following Homework Statement 1.potassium iodine, 2. calcium flouride, (these two are...

Homework Statement how would you draw this structure in 3d using dash-wedge representation? HN=C=CH2 From my guess, I drew the N=C=C as being parallel, and the two hydrogens coming off the second C without having any dashes or wedges, but curving at 120 degrees from the carbon. For the...

subjects like Solid state chemistry, QFT, QCD, general relativity, particle physics, etc look interesting to me and i really would like to master them at some point. so far i have taken basic physics, calculus i-iii, introductory courses to ODE and PDE, pchem, and 2 introductory modern...

I was wondering does bromide react with propanol or propanal at all? Also, what answers do people get for this question, i say it either propanol or propanal as i don't know if either reacts with bromide and both would be a suitable answer. The question is: Compound A has a molar mass...

Hi, I'm wondering how can i differentiate when the molecule is an SP3, SP2 or SP hybrid orbitals? Like for example C2H2 and C2H4. What can i do in order for me to know?

This doesn't seem like it should be too hard, but I'm stuck... Am i making a stupid mistake somewhere? 1. The density of potassium metal is 0.89 g/cm3. Potassium's atomic radius is 231 pm. Assuming that r nuc = 10^-4 x r atom, estimate the density of an essentially spherical 39K nucleus...

I'm going to be a senior in hs this fall and am still fretting over my schedule. It's either IB Chem or AP Comp Sci A. I can't take ap chem because i don't have space for the dbl pd class but ib covers most of it and with a little self-study (i have had friends who successfully done this...

Homework Statement Name the following compound: CH3CH2C(CH3)2CH(CH2CH3)CH2CH2CH3 It's an alkane (Is there a way to see that it's an alkane when it's in this format?) Homework Equations The Attempt at a Solution I really have no idea where to start. I can name compounds...

Homework Statement Find the molarity of the solution (salt and any excess reagent after reaction of 250 mL of 0.05 M Ba(OH)2 with 200 mL of 0.08 M HNO3. Homework Equations The Attempt at a Solution I am drawing a blank. Here's the balanced equation Ba(OH)2 + 2HNO3 ===> 2H2O + Ba(NO3)s...

Hi, I was wondering if studying these CHEM courses all in the same year would be too much for a person that is studying Biotechnology, and thus I am taking 4 other Biology courses with another needed humanities credit. The CHEM courses are: Fundamentals of Analytical Chemistry...

Could someone explain to me how to solve this? I have a 10 gallon solution made up of 6.40%Cl, 5.52%Na, and 4.11%Ca, with a density of 1.21. How much HCl is needed to get the %Cl up to a 6.60%, and what would the theoretical %Na and %Ca be after the HCl addition? Can anyone show me the...

I am an undergrad student studying chemistry and I was wondering from the pros what classes you thought were the most interesting or helpful after school.

How necesary is Programing C for a civil engineer or all engineers? Why do colleges require some programing for engineers. Also for a civil engineer, how important is GENERAL CHEMESTRY 2, since is not mandatory at the University i'll be transfering, but it is a transferable course along with...

Can someone please help me with this back tritration problem! a 100.0 ml sample of spring water was treated to convert any iron present to Fe2+ (AW 55.847) Addition of 25.00 ml of .002107 M K2Cr2O7 (FW294.185) resulted in the reaction: 6(Fe2+) + (Cr2O7)(2-) + 14H+ _____6(Fe3+) + 2(Cr3+) =...

It's been two years since I finished CHEM 1411, and I'm taking CHEM 1412 (General Inorganic Chemistry 2) this summer. What should I review specifically from 1411 to be adequately refreshed? Thanks.

[Xray reflection 1. Homework Statement X-rays of 1.54 angstroms are reflected off copper powder @ 21.65º 25.21º 37.06º 44.96º 47.58º Find the cubic lattice and the length of an edge of the unit cell. 2. Homework Equations nλ = 2d sin(Θ) ; the Bragg equation 3. The...

Hey guys, I am studying for my final for Gen Chem and will be taking the ACS gen chem exam this week. Has anyone here taken it before and if so, what equations and/or constants will be given? Thanks for the help guys! Medline

A bauxite ore 86.0 percent Al2O3 by weight. How many grams of the ore are required to produce 20.0 grams of aluminum metal? (Formula masses: Al2O3=102 & Al=27.0) A) 12.3g, B) 32.5g, C) 37.8g, D) 43.9g So this is how I did it on the test but got it marked wrong. I reasoned take 1/.86=1.16...

Hi everyone, I was wondering what you all recommend for studying/reviewing Introductory University Chemistry. I heard good things about the Silberberg textbooks, while I used Zumdahl at my school. So I was wondering, do you all think that Silberberg is better or should I maybe study a bit...