Recent content by josephcollins

I solved it thus: (n^2 + 2n)^1/2 = (n^2)^1/2 * (1+2/n)^1/2 therefore this = n(1+2/n)^1/2 now expand the bracket using taylor's theorem to get (1+2/n)^1/2= 1+(1/n)-(1/n^2)+... therefore multiplying by n in the above you have n+1-(1/n) as n tends to infinity the (1/n) becomes...

I have a short question concerning the dilution of a 0.01M solution of HCN. I need to dilute 40cm3 of the above to give a solution with a pH of 6. Given the Ka of HCN is 4.8*10^-10 I obtain the concentration of HCN necessary in the new volume:2.08*10^-3M. Therefore the volume has to be...

Hi ppl. I have a short question. A meteorite of mass m has a velocity u=2.00*10^4 m/s when it is at an infinite distance from the earth. It eventually collides with the eath with a velocity v. Calculate v. given are the radius of earth(6.37*10^6m) and go=9.80Nkg^-1) I used the argument that...

Hi ppl. I have a question. I'm given the pka of ethanoic acid/ethanoate ions at 4.75 and i have to work out the ph of a 5*10^-2 moldm3 solution of sodium ethanoate. I worked it out by getting the Ka from 10^-4.75 and then saying that the concentration of Ch3COO- in the dissociation of ethanoic...

The way I was introduced to e was to try to find the exponentional which was its own derivative. So say we have a^x, we know that a^0 is 1, so try to find the value of a such that the gradient of a^x is 1 at the point (0,1). From this you get the definition of a, or as we know it e: Lim...

Hi my friend. What you should do here is write first the equilibrium reaction for these two substances ionisation in water, then deduce an expression for Kc-eqm constant. This expression will include the concentration of water, which is constant and thus cancels out of the equation. Then replace...

HI ppl, I have a question here. I deduced a formula of an acid, aminobenzoic acid and this reacted with ethanol to give the corresponding ester. This ester then reacts with an acyl halide, CH3COCl, any ideas as to the product of this reaction? Thanks, Joe

Hi ppl, I have this question. I have the MF of a substance A : C7H7O2N. I have three pieces of info which should indicate a structural property of this substance:i) A reacts with sodium carbonate to give off CO2. I thought this might indicate an ionic structure? then ii) A will form a coloured...

Hi ppl. May I ask how you obtain the range of convergence for the maclaurin expansion of ln(1-x) and taylor's series, maclaurin's in general? Thanks, Joe

Here I have a problem: A 232/92 Uranium nucleus emits an alpha particle with kinetic energy=5.32MeV. What is the final nucleus and what is the approximate mass(in units) of the final atom. I can write the equation for the reaction, this will give 4/2 He and 228/90 Th. If the alpha particle...

Here I have a problem: A 232/92 Uranium nucleus emits an alpha particle with kinetic energy=5.32MeV. What is the final nucleus and what is the approximate mass(in units) of the final atom. I can write the equation for the reaction, this will give 4/2 He and 228/90 Th. If the alpha particle...

I used the fact that delta(y) is roughly equal to delta(x) times dy/dx. Then you come up with y(3)-y(1)=(e^1/1)(3-1). I think this gives y(3)= 2e+2. Could someone verify that this is the correct approximation? Thanks, Joe

You might also remeber to use the maclaurin's series for sinx. since sinx= x-x^3/3! + x^5/5! the x's will cancel and give 1 and the rest of the terms in x will become negligible for the given limit as x tends to zero, Joe

Hi ppl, I have an electrochemisry question. Explain why dilute sulphuric acid, rather than dilute hydrochloric acid, is used as a source of hydrogen ions in the volumetric estimation of iron (II) ions with potassium manganate (VII).

Hi ppl. I'm asked a question: Iron filings are added to a solution containing the ions Cu2+, Fe2+, Fe3+, H30+ and Zn2+. Deduce what reactions occur from the standard electrode potentials. Is this simply asking me which will change Fe2+ to Fe3+ and vice-versa by reduction or oxidation do you...