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A simple reminder to all: this is the "Homework Help" forum, not the "Homework Answers" forum. We will not do your work for you, only point you in the right direction. Posts that do give the answers may be removed.

  1. We're currently on the Equilibrium unit, and I'm having problems with some questions. 1) Given a 0.015 M solution of HOCN with a pH of 2.4, find the ionization constant, Ka. I know that ka = ([H+] [OCN])/ [HOCN], and i can calculate for the concentration of H+ and HOCN. But how do we find the concentration of OCN>? 2) Given a 0.015M solution of an unknown base with pH10, find: a) The concentrations of hydroxide and hydronium ion b) Kb I think for part a) I use the -log[H+] = 10 to find the concentration of H+. But then what about hydroxide? And as for b), Kb = Kw / Ka, but since we don't know Ka, how do we solve for this? Sorry if it's a …

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  2. Started by mooeypoo,

    In one of my solution-guides, they're trying to solve an integral of this form (to later get the root mean square velocity): [math]<v^2>= A \int v^4 \exp{\frac{-Mv^2}{2\tau}}dv[/math] I was thinking of doing this by integration by parts, and trying to reach a gaussian integral or something like that, but I totally miserably failed; it became really complicated. The book solves it by u-substitution, only I don't quite get what they're doing there. They're saying first (and this I understand) that [math]u=\frac{Mv^2}{2\tau}[/math] But then they simply state that [math]v^4 dv=\frac{1}{2}\left( 2\tau/M \right)^{5/2} u^{3/2} du[/math] .... h…

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  3. Started by Obelix,

    Ok, we've warmed up enough! Now for the real thing: Let [math](G,\cdot,T)[/math] and [math](H,\ast,S)[/math] be topological groups, [math]H[/math] being connected as a topological space, and let [math]f : G \rightarrow H: g \rightarrow f(g)[/math] be a homomorphism of topological groups, i.e.: [math]f : G \rightarrow H :[/math] Continuous, and: [math]f(g_1\cdot g_2)= f(g_1) \ast f(g_2)[/math] (or [math]f(g_1 g_2) = f(g_1) f(g_2)[/math], in simplified notation) [math]\forall g_1, g_2 \in G[/math]. Suppose moreover that [math]int_{S}f(G) \equiv f(G)^{\circ} \neq \emptyset[/math], i.e.: [math]\exists \, g \in G, U \in S[/math] such that: [math]f(g) \in U \subseteq f(G)…

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  4. Started by mooeypoo,

    Hey guys, I'm studying for my thermo exam, and I have this homework problem: Okay, so here's what I did: Electrons have 2 possible spins, so my usual "n" would be doubled in occupancy, hence N=2n. And: [math]\epsilon=\frac{\hbar^2\pi^2 n^2}{2m L^2}=\frac{\hbar^2\pi^2 N^2}{8m L^2}[/math] And solving for N, gives me [math]N=\frac{2 \sqrt{2m \epsilon}L}{\pi \hbar}[/math] The energy of the highest filled orbital in the ground state of a free particle gas of fermions of spin 1/2 is [math]\epsilon_F=\frac{\hbar^2}{2M}\left( \frac{3\pi^2N}{V} \right)^{2/3}[/math] And the density of orbitals at [math]\epsilon_F[/math] is [math]D(\epsilon_F)=\…

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  5. Started by Vastor,

    the Question say, Find the range of value of p for which the straight line [math]y = 2x + p[/math] does not intersect the curve [math]x^2 + y^2 = 20 [/math] so, i dun have any idea how to start.. the textbook don't tell me anything.. so, help anyone?

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  6. Started by helpmeplease,

    I just want to know the basics of how the alleles that make up the genotype of a child at each locus are derived from his or her parents’ genotypes. I really need some help with this, I'm totally stuck, If anyone could help i'd really appreciate it.

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  7. Started by KillRoad..,

    Hello, can someone please help me. So.. I need to build circuit with two reversible motors.. I need to make something like reversible fan system, one fan goes forwards, other backwards.. ofter couple hours they reverses.. I have AC 220V supply. question is.. how can i make this up easier ? The simplest solution is The best. All needed to be automatized my thought is use timing relay, inverters ? What kind of motors i need to use ? reversible AC motors would be The best chose i think.. If i use DC motors that would be messy, needed to change supply from AC to DC, yes, its not so hard, using diode bridge and stuff, but then voltage drops.. and again it's problem…

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  8. Started by Obelix,

    Ok, let's make it more interesting! Let [math]G[/math] be a group, and suppose there exist three consecutive integers: [math]n-1, n, n+1[/math] such that: [math](ab)^{n-1} = a^{n-1} b^{n-1}, (ab)^n = a^n b^n, (ab)^{n+1} = a^{n+1} b^{n+1}, \forall a,b \in G[/math]. Show that [math]G[/math] is abelian. Also show that such a conclusion needs not hold if the condition is assumed for only two consecutive integers.

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  9. Started by Obelix,

    The following holds: If from any integer we subtract the sum of its digits, then the result is divisible by 9. E.g. take 1456. The sum of its digits is: 1 + 4 + 5 + 6 = 16. Then: 1456 - 16 = 1440 = 160 x 9. Give a rigorous proof of the above statement! How does it generalize?

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  10. Started by dragonstar57,

    i did a ppt about how to do a Vigenère cipher and a caesars shift cipher and i asked someone YA the next method to try and they said RSA. so i was hoping someone could explain how to use the RSA algorithm without the use of a computer? I have been showing the class ciphers that can be used with just a pen and paper. I guess if you have a better idea for the method than i guess that's ok to ps i want to do this one because i have an interest in the subject (it's one of my few interests) and haven't been able to learn any thing new about it because of the mathematics is a little beyond me (i'm about to finish an algebra one class for my high school)

  11. Started by Vastor,

    My note i need someone to check the note i made, who know how to 'simplify' and give better idea for better presentation and maybe fix something that wrong in my notes. btw, the most problematic in the notes is Quadractic Function, it's kind of messy and if u got any idea to modify it, post here.. thnx ^^

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  12. Punnet square question? True breeding punnet square? I got the right answer but need some clearing up. true-breeding dwarf and true breeding maize plants produced all dwarf plants in F1 . in the f2 generation dwarf and tall plants segregated 3:1 ratio. Dwarf F2 plants self pollinated. what proportion of the resulting plants would be expected dwarf let BB=Dwarf bb=tall BBXbb F1= 1 Bb Bb x Bb F2=1 BB:2 Bb: 1bb now it gets tricky.. so there is a 1/3 chance that BB x BB but a 2/3 chance that Bb x Bb...what I am confused about is what about the chance Bb x BB? ......................................… if BB and BB were crosses all offspring wou…

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  13. Started by CaptainBlood,

    If the product of two numbers if 5, and the sum of these same two numbers is 4, what's the sum of the reciprocals of these two numbers? I tried: let's say we have two numbers a and b, then a*b = 5 a = 5/b since their product is 4, we get b + 5/b = 4 or b^2 -4b + 5 = 0 but this has no real solutions just imaginary because this function is > 0 for all b I can't factor it and the quadratic formula doesn't work since 4^2 < 4*1*5 also the derivative is 2b -4 = 0 so b = 2 is the minimum since second derivative is positive but that doesn't help either. What do I do?

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  14. Started by hkus10,

    1) (x-10)[(x+4)(x+1) - 24] - 3[(-11x - 11) + 24] + 8[-21 + 3x] what I get is (x-10)(x^2+5x-20) + 57x-207 The reason that I do not combine them is because I think it is much more difficult to deal with x^3? What should I do here?

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  15. Started by raid517,

    If an arrow on Earth is fired into the air and reaches a hight of 125 m and penetrates the ground where it lands to a depth of 25 cm, what is it's deceleration? Of course the acceleration due to gravity is 9.8 m s, but I'm stumped on how to calculate deceleration? I successfully calculated the final velocity to 49.5 m s^-1.

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  16. Started by Jay234,

    Hey, can you guys answer this question(s) about Stem-cells. What are the ethical arguments for and against stem-cell research? What ethical issues might arise when a drug company funds trials of a new drug it has developed to treat a genetic disorder? Who should determine how the results of transgenic research in plants and animals will be applied?

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  17. Started by 1123581321,

    i was wondering how you find how many electron have been removed if the resultant charge is +3.38 pC (3.38x10-12C). given the charge of an electron being -1.60*10^-19 C

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  18. Started by hkus10,

    Let P belongs to Mnn be a nonsingular matrix and Let L:Mnn>>>Mnn be given by L(A) = P^-1AP for all A in Mnn. Prove that L is an invertible linear operator. I have no clues how to start this question. What do I need to prove for this question? and why

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  19. Started by hkus10,

    Let L : V>>>V be an invertible linear operator and let lambda be an eigenvalue of L with associated eigenvector x. a) Show that 1/lambda is an eigenvalue of L^-1 with associated eigenvector x. For this question, the things I know are that L is onto and one to one. Therefore, how to prove this question? b) state the analogous statement for matrices. What does "state" the analogous statement mean? Thanks

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  20. Started by Norb,

    hey guys i have recently found my weak point in science. CHEMISTRY i am really bad at chemistry and need this mark like you wouldnt believe. its a grade 10 chemistry assignment. here is the microsoft word assignment less22_u1_reviewassignment.doc if you can asnwer any of those question to help em out it would do wonders for me! thanks! im willing to pay as well....... for the help....my msn is: Norb_y@hotmail.com its a _ mark between norb and y not a space!

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  21. Started by Teggle,

    I've been given the question of: Derive the following function to find the velocity and acceleration: s=0.3cos(pi/4*t) I am unsure of how to do this properly with this particuar function. It would also help if someone could let me know how to put this function into Graphmatica. I know you have to go to Tools and then down to Functions to enter it into the program, but I don't know how to write it so it will work, as an error keeps coming up when I try to enter it as I have written above. Thanks to all who can help.

  22. hi, i was wondering if anyone knows any websites or videos which effectively cover the lesson on thermal energy, heat and temperature. for some reason i can't seem to pick things up in class so i have to go looking for lessons on my own time. thank you for your help.

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  23. Started by Clueless,

    Hey, I am currently studying basic chem, and i'm currently writing a paper on precipitation reactions- However I am uncertain as to what exactly an iconic solid is. Is it incorrect to say that it is basically a insoluble ionic compound? If not, then is it of the same structure as a iconic compound? Grateful to anyone who can help

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  24. Started by lwalsh90,

    Hi everyone, I'm a sophomore biochemistry, cell, and molecular biology student currently enrolled in a microbiology course. We have been assigned an unknown bacteria and must identify it's taxonomy, genus and species based on a series of tests. My tentative identification of the bacteria currently is Alcaligenes Faecalis. However, a few of the test results are misleading me from my tentative ID, but I'm not sure what else it can be. Below is the list of possible unknowns (some on the list are definitely not possible being they are highly pathogenic). I have also listed my current test results and any relevant attached pictures. (All images taken under the micros…

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  25. Started by tino010,

    What property does a membrane pump contain but a membrane carrier does not? I know both flux depend onan electrical gradientbut what are the differences in each? Thanks in advance.

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