Thursday

July 31, 2014

July 31, 2014

Total # Posts: 40

**calculus**

using L'Hospital's rule, evalutate; LIM as x->0 e^x +cos x / e^x + sin x I'm at LIM x->0 e^x+cosx / e^x +sinx but now I at a lost as to how to proceed.

**calculus**

let xy + x^2 = x find y'

**calculus**

Let 4xy^3 - x^2y= 5x - 6 - x^3 where y is a differential of X. Find y' in terms of x and y. I get: y'= -4y^3 - 2xy + 3x^2 -5 / x^2 -12xy^2 My answer handout shows the answer as positive. Which should it be, neg. or pos.? Thanks

**organic chemistry**

How do I go from C-triple bond-C and end up with [(Z)-6 methylhept-2-enyl] benzene. I think the first step is adding NaNH3, but after that I'm lost.

**chemistry**

In deciding which has more entropy, would it be correct to say s<l<g<aq or s<l<aq<g I'm thinking the second one....

**chemistry**

gottem' both. thanks anyway. I'm sure I'll have more questions on down the road.

**chemistry**

I figured out the Zinc problem, but still need some help with the other one.

**chemistry**

Balance each of the following redox reactions occurring in acidic aqueous solution.Express your answer as a chemical equation. Identify all of the phases in your answer. Zn(s) + Na(aq)-> Zn2+(aq)+Na(s) Cl-(aq) + 2NO3-(aq)->NO(g)+Cl2(g)

**chemistry**

Explain why methanol spontaneously evaporates in open air at 25.0 . I know that a negative delta G means a spontanious reaction, but I don't think this is an adequate response to this question. I need a little more clarity about this. thanks

**chemistry**

Thank you so much! I see what I was doing wrong now. I need more practice with these type problems.

**chemistry**

Calculate the percent ionization of a 0.15 formic acid solution in a solution containing 0.11 potassium formate. I have the formic acid Ka=1.8 *10^-4 When I solve for "x" I'm getting 1.1.44*10^-2 When I plug that into equation (x/0.15-x)*100, I'm getting 10.6...

**poetry**

actually all that matters is what my instructor thinks it means

**poetry**

What is the author, Andrei Codrescu, trying to saying in "A Leafy Angel?"

**chemistry**

This is from a "effect of pH on the solubility of Ca(OH)2" lab: If excess Ca(NO3)2 were present, what effect would it have on the solubility of Ca9OH)2? also, in a "effect of comlex ion formaiton on the solubility of NiCO3" lab": If HCl(aq) were added ...

**chemistry**

What chemical reaction is responsible for the endpoint observed when the NH3/NH4Cl buffer solution is titrated with HCl? Write a blanced ionic equation for the reaction.

**poetry**

I'm trying to understand the meaning of Tom Dent's poem "secret messages" (for Danny Barker). What is he trying to say? I'm thinking in the first stanza, the rain is washing away the past and "bad" history of blk mammies chained to praline shops...

**chemistry**

Based on their molecular structure, how can you figure out which is stronger between two oxyacids? Our textbook is really vague. I thought it had to do with which had more oxygen but one of the question compares CH3COOH and CCl3COOH so now I'm lost again.

**chemistry**

Thank you so much for ALL your help. You make it so simple and easy to understand.

**chemistry**

Based on their molecular structure, why are these acids thes stronger of the two binary acids given? HCl stronger than HF HF stronger than H2O H2Se stronger than H2S Is this because of bond strength due to placement on the table of elements? thanks

**chemistry**

nevermind. I got it. it's 2.9 x 10^6 kg. but thanks anyway

**chemistry**

If the pH of a 1.00in. rainfall over 1400 miles^2 (square) is 3.20, how many kg of sulfuric acid, H2SO4 are present, assuming that it is the only acid contributing to the pH?

**chemistry**

What is the pH of a solution with [H+]= 4.75 x 10^-5? I set this up as: pH= -log[H+] =-log (4.75 x 10^-5) = 4.32 Is this the correct to solve this? thanks

**chemistry**

That does help greatly. Thank you so much!

**chemistry**

Okay, thanks. The choices offered are phosphoric acid, citric acid, a oxalic. Let me make sure I'm understaning you, for example: I have an equilvenc point at 4.80mL and the pH at that point read 6.93. So I should go to 3.5 and the pH at that point is 5.69. So K= 5.69? or ...

**chemistry**

We titrated Sprite with 0.1051 M standard NaOH. I've ploted three different titrations and am supposed to use the titration curve to identify the acid. I assume the acid is Citric since it's Sprite, but the lab manual also says "to recall that two K values must be...

**chemistry**

Why should the volume of standard base (or acid) needed to reach the equilvalence point in a titration be more than 10.0 mL?

**calculus**

never mind. I figured it out. That is the correct anser, I didn't carry through with the derivitives.

**calculus**

find f'(x) for the following: f(x)= cos^5(4x-19) I keep getting 20cos^4(4x-19)sin, but the answer is supposed to be -20cos^4(4x-19)sin(4x-19). I can't seem to get there with derivatives

**CALCULUS**

THANK YOU!!!!!!

**CALCULUS**

find f'(x) for f(x) = x/(sqrtx^2+1) please show all the steps. I'm realy confused on this one. I get as far as setting it up using the quotient rule then I go blank. thanks

**chemistry**

thank you!

**chemistry**

For the ionization of a weak acid, HA: a) give the expression for Ka. b) after taking the log 10 of both sides ofthe quation in "a" sp;ve fpr pH. c) under what conditions would pH be equal to pK?

**chemistry**

Now I can. Thanks. Our labe manual is an "experiment" for next year's classes, so a lot of info has been left out in error and we have to fend for our selves. I really appreciate the help.

**chemistry**

find the pK for the following ionization constants, K= 1.8*10^-5 and 1.1*10^.2

**chemistry**

Yes, it does. Thank you!

**chemistry**

When acetone is added to saturated sodium chloride, the equilibrium shifts toward the right. What is the role of acetone in shifting the equilibrium toward the right? any help would be appreciated. My TA is of no use in explaining our lab experiments. thanks

**Cheistry**

When acetone is added to saturated sodium chloride, the equilibrium shifts toward the right. What is the role of acetone in shifting the equilibrium toward the right? any help would be appreciated. My TA is of no use in explaining our lab experiments. thanks

**chemistry**

Why would it not be useful to just use pure ethanol or pure ethylene glycol as an antifreeze since their normal freezing points are -114.1 C abd -12C respectively.

**chemistry**

thanks

**chemistry**

calculate the necessary amounts of solutes and solvent to make a 4l bottle of antifreeze that will have a 35 degree change in the freezing point of water. soultes are: Al2(SO4), KBr) and Mg(NO3)2.

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