Chem 2 homework help?
0.0 mL 1.7 x 10^-9 = x^2 / 0.100-x x = concentration OH- =1.3 x 10^-5 M pOH = 4.9 pH = 14 - 4.9 = 9.1 4.0 mL Moles pyridine = 0.0250 L x 0.100 = 0.00250 moles HCl = 0.004 L x 0.100 = 0.0004 C5H5N + H+ >> C5H5NH+ moles C5H5N = 0.00250 - 0.0004 =0.0021 moles C5H5NH+ = 0.0004 total volume = 29 mL = 0.029 L concentration C5H5N = 0.0021 / 0.029 =0.072 M concentration C5H5NH+ = 0.0004 / 0.029 =0.014 M C5H5N + H2O <----> C5H5NH+ + OH- 1.7 x 10^-9 = ( 0.014+x) (x) / 0.072 -x x = concentration OH- =8.7 x 10^-9 M pOH =8.1 pH = 14 - 8.1 =5.9
Chem 2 Help!!?
Notdumb is a drug widely used to treat stupidity. A solution prepared by dissolving 25.5 g of notdumb in 30 mL of water has a freezing point 2.55°C below that of pure water. What is the molar mass of notdumb (density of water is 1.00 g/mL and Kf = 1.860C/m)? [i = 1 for Notdumb]
Help chem question! gen chem 2?
Apparently the reaction is at 22^C 4 times as fast as at 1°C Assuming all other factors are the same the rate constant makes the difference. Dependency of rate constant on temperature is given by Arrhenius equation. k = A ∙ e^( -Ea/(R∙T) ) If you know the rate constants k₁ and k₂ at T₁ and T₂ respectively, you can calculate activation from their ratio: k₁ = A ∙ e^( -Ea/(R∙T₁) ) k₂ = A ∙ e^( -Ea/(R∙T₂) ) => (k₂/k₁) = [A∙e^( -Ea/(R∙T₂) )] / [A∙e^( -Ea/(R∙T₁) )] <=> (k₂/k₁) = e^( (Ea/R)∙(1/T₁ - 1/T₂) ) <=> ln(k₂/k₁) = (Ea/R)∙(1/T₁ - 1/T₂) <=> Ea = R∙ln(k₂/k₁)/(1/T₁ - 1/T₂) For this problem T₁ = 274K T₂ = 295K k₂/k₁ = 4 => Ea = 8.314472J/molK ∙ ln(4) / (1/274K - 1/295K) = 44365J/mol = 44.365kJ/mol
CHem 2 question pleaz help?
hydrogen bonding, the formula of formic acid is HCOOH, the hydrogen next to to the oxygen is partially positive due to the difference in electronegativity between O and H, therefore it is a polar bond. Hydrogen bonding only occurs when H is bonded covalently to N, O, and F. It is in essence a very strong dipole - dipole interaction, and due to its strength is called hydrogen bonding. This polarity allows the H atom to be attracted to the O atom from another molecule, so it forms hydrogen bonds which is a type of intermolecular force. Intermolecular means between two different molecules.
Chem 2 help please! Calculate the molality of each of the following solutions.?
The mass of 1 moll Benzene is 78,108 gram. You can calculate the mol mass by taking the mol mass of all the seperate Elements of a Molecule together. The atom mass is displayed in the periodic chart in amount of u but this is the same value as the amount of g/mol for the element. Example; C6H6 is 6 x 12.01 (carbon) + 6 x 1.008 (hydrogen) = 78.108 g/mol Hope you followed me on that. So 1.0 mol = 78.108g so 8.64g = 0.11 mol Benzene (divide the amount you have by the mol mass, ie; 8.64/78.108= 0.11) Next you need to know how many times the 23.3 g fits in a kg because molality is measured in mol/kg, but this one is simple. 1000/23.3 = 42.92 times. Since there was 0.11 mol in 23.3g there should be 42.92 times as much mol in 1000g. (as we just calculated) which is 4.7 mol meaning theres 4.7 mol/kg which is the molality For the second one i'd say you might give it a go yourself now. After all, by trying yourself, you'll learn the most. If you really dont get it i'll explain that too. ps: 1 l water = 1kg water
Need Chem 2 Help ... please explain?
9. In the compound, CaNa[Fe(CN)6], what ligands are in the coordination sphere? A. Ca2+ B. Na+ C. CN- D. H2O E. none of these 10. What are the respective central-metal oxidation state, coordination number, and overall charge on the complex ion in Na2[Cr(NH3)2(NCS)4]? A. +3; 6; -1 B. +3; 6; +1 C. +2; 6; -2 D. +2; 4; -1 E. +1; 6; -2 11. In the following reaction, Ni2+ is acting as a(n) __________. Ni2+ (g) + 6H2O (l) → Ni(H2O)62+ (aq) A. oxidizing agent B. Lewis acid C. precipitating agent D. solvent E. ligand 12. Which one of the following species is paramagnetic? A. Cu+ B. Cr3+ C. Zn D. Ca E. Ag+ 13. How many d electrons are in the cobalt ion of K3[Co(CN)6]? A. 3 B. 5 C. 6 D. 7 E. 4 14. What is the charge on the complex ion in Mg2[FeCl6]? A. 2- B. 2+ C. 3- D. 3+ E. 4- 15. What is the oxidation number of chromium in [Cr(NH3)4Cl2]Cl? A. -3 B. +3 C. +2 D. -2 E. 0
Chem help! Oxidation numbers!?
I have a feeling you have the same chem teacher as me haha because I have all 3 of these problems on my assignment...I found this and it helped me with those and I got +7 for the first, -1 for the second, and +5 for the third 1) For the atoms in a neutral species (i.e. an isolated atom, a molecule, or a formula unit), the sum of all the oxidation numbers is O. Ex: Fe(s) atom has an oxidation number of 0; the sume of the oxidation numbers of all the atoms in Cl2 and C6H12O6 is 0; The sum of the oxidation numbers of the ions in MgBr2 is 0. 2) For the atoms in an ion, the sums of the oxidation numbers is equal to the charge on the ion. Ex: The oxidation number of Cr in the Cr+3 ion is +3. 3) In compounds, the group 1 metals all have an oxidation number of +1 and the group 2 metals all have an oxidation number of +2. Ex: The oxidation number of Na in Na2SO4 is +1. 4) In compounds, the oxidation number of fluorine is -1. 5) In compounds, hydrogen has an oxidation number of +1. 6) In most compounds, oxygen has an oxidation number of -2. 7) In binary compounds with metals, group 7 elements have an oxidation number of -1, group 6 have an oxidation number of -2, and group 5 elements have an oxidation number of -3. Ex: The oxidation number of Br is -1 in CaBr2. So lets do an example: KClO4 According to rule 3, the oxidation number of K is +1. According to rule 6, the oxidation number of O is -2 and the total for 4 O atoms is -8. For these two elements , nsthe total is +1 - 8 = -7. The oxidation number of Cl must be +7 to give a total of zero for all atoms in this formula unit.
I have only 1 day left for my chemistry 12th board exam and I don't know anything. What are some important topics from chapter 1 to 15 so that I can get at least passing marks?
No need to concern friend, be happy and try to make peaceful of your mind, lot of people's suffering like as you, life isn't about finding yourself, it's about create your self, exams, will respassing, until you will stop your studies, I'm just trying to motivate to you, don't concern about this exam, probably if you had got good marks in this exam, nobody would appreciate of ur marks except your parents, your exam result do not define you as a person and or predict your future,nobody ask you in the future how many marks you were got in chemistry, to give a job, they only ask you what you create in your life to it will be useful to people's,“Don't let grades define you courtesy of”,But I'd like to assist to pass the exam, as your mind set idnt remember those topics bcz it's being some many yrs to completed my 12,but however Im remember those topic for you.1. polymers(uses and momomers of all polymers, reaction.2.solid state packing3.solutions_all collective props4.surface chemistry all Def, and colloids5.coordinate come all Def, cut, isomerism6.RX ARX-All mechanism(sn1, 2,se,na)7.amines Hoffmann Bron amide, Gabriel phthalate, carbylmine, and Diamonique.Pardon me frnd if you not understand of myy ans, gratitude I implore to god you will pass the exam. “God Willing”.
Addition of HBr to aromatic benzene with propene group?? Please answer?
I just took my O-Chem 2 exam and I think I did alright on all the alcohol reactions and nmr... I am just confused about this question.. if HBr adds to an aromatic benzene which has a propene group attached to it, where will the Br add? This is a picture: http://wtt-pro.nist.gov/wtt-pro/index.html?cmp=~e~-1-propenylbenzene Since both sides of the double bond are secondary, where will it add? It will NOT add ortho or para ON the ring, right? It was a MC question and the answer choices were Br adding meta on the ring, adding para on the ring, adding on the left side of the propene double bond, and on the right side (so getting rid of the double bond)... I put on the right side of the propene group but I am just not so sure. please help.. and thank you!
Does everyone who majors in chemistry memorize the periodic table of elements?
Generally, No.However, what do you mean by “memorizing the periodic table of elements”? Are you satisfied with knowing the atomic number, name, and symbol of all discovered elements so that you could fill in a blank chart with that information? Even with just that, most chemistry majors do not memorize the whole thing—typically the first three rows (through Ar), probably groups 1, 17, and 18, plus a few other common elements scattered through the table. A few will go farther and even memorize the whole thing. (At the other extreme I was not a chemistry major, but I know all 118 elements by name in English and German in order of atomic number, as well as their symbol—not because it is valuable from a chemistry standpoint, though it can be convenient on occasion stored in the mind, but more to keep my mind exercised.)Now, if you also mean some other properties that many charts show (such as atomic weight, electronegativity, primary oxidation numbers, electron shell structure, etc.), I expect a very few people do memorize much of that (I did not, though I have a big picture or ballpark idea of many of those things).Is it useful to memorize this stuff? Yes, there is some payback for the effort. Is it really worth it? The details probably are not, and there are usually better ways to spend your time. Yo will usually have fairly easy access to a chart, and that is quite good enough in most cases.