Thursday
January 29, 2015

Posts by Devron


Total # Posts: 986

Chemistry--Typo
I meant to say solve for Ka and not x.
January 28, 2015

Chemistry--Typo
Typed something out of habit. plug in the value for x and solve Ka: I apologize about that.
January 28, 2015

chemistry
HA ----> A^- + H^+ Ka=[A^-][H^+]/[HA] ....HA........A^-....H^+ I ..0.22 ......0......0 C..-x..........x.......x E.0.22-x....x.......x Ka=[x][x]/[0.22-x] Let x=0.22*(0.209) Solve for x:
January 28, 2015

Chemistry
I think this has to do with the orbital stuff that you learn in organic chemistry, and/or physical chemistry, or some other chemistry courses. I think you should go with A, collection of balloons. This is what that orbital stuff looks like in a book; I hated that orbital stuff...
January 28, 2015

Chemistry
You have to do your own work. Maybe just post what you think it is and why.
January 28, 2015

chemistry
The nucleus contains what? Positively charged protons and neutrons, so what is it likely to attract? Therefore, what is shielded? I think you may be on to something.
January 28, 2015

Chemistry
It doesn't detect hydrogen nor helium, so that only leaves one answer.
January 28, 2015

chemistry
I've told you enough.
January 28, 2015

chemistry
NMR is usually abbreviated as 1H NMR. So, I'll let you answer that question as well.
January 28, 2015

Chemistry
The word in electron in photoelectron spectroscopy should eliminate answer choice C. Can you excite core electrons? Look for images to see how this works.
January 28, 2015

chemistry
That last part of my sentence should have said, "D should be answer choice C."
January 28, 2015

chemistry
I think the answer is A, but I am not sure. I believe that Low frequency radio waves are used, which eliminates answer choices B and D, which should be answer choice C. I have used NMR is performing research, but I never had to know the type of frequency used nor did I care to...
January 28, 2015

Chemistry
Density=mass/volume Density of Bromine=586g/188 mL ***Answer contains 3-significant figures
January 21, 2015

chemistry
42.45-mL=0.04245L 0.8743 g sample of KHP*(1 mol/204.22 g)= moles of KHP moles of KHP=moles of NaOH Molarity (M)=moles of NaOH/0.04245L **Answer contains 4-significant figures
January 21, 2015

Chemistry
The retention time looks good for A, except that you should have 0.792-- one more significant figure, so I will move on to the next problem. This is only for A, and I think you can perform the rest after I am done. To solve for the distribution constant, perform the following...
January 21, 2015

Chemistry
First, determine the number of moles for CH3COOH (HAc), CH3COONa (Ac^-), and HCl Molarity=moles/Volume (L) Moles=molarity*volume (L) Moles of HCl=0.1M*0.010L=x Moles of HAc=1.0M*0.025L=y Moles of Ac^-=0.5M*0.025L=z Calculate the pH of the buffer: pH=pka+log[A^-/HA] Where pka=4...
January 19, 2015

Chemistry
Answered this for you in your subsequent post.
January 19, 2015

SCIENCE--Typo
Initial velocity=time*deceleration=4s*9.8m/s^2=39.2m/s
January 19, 2015

SCIENCE
It takes the arrow 4 seconds to reach the top and 4 seconds to reach the bottom. Solve for height: d=1/2at^2=1/2(9.8m/s^2)*(4s)^2=78.4m Initial velocity=time*deceleration=4s*9.8m/s^2=39.2m
January 19, 2015

Physics
Doesn't matter when you convert it, but the units have to be the same once you perform the calculations. Conversely, you could have just converted the acceleration from m/s to km/h. I thought it was easier to do by converting the velocity. Best.
January 18, 2015

Physics
Then the answer should be answer choice A, and not B. Acceleration=change in velocity/time Change in velocity/acceleration=time So, 110km/h=30.56m/s and 70km/h=19.44m/s (30.56m/s-19.44m/s)/3.8m/s=t t=11.12m/s/3.8m/s t=2.9s
January 18, 2015

Physics
I hope the speed is km/s You will have to convert km/s to m/s Acceleration=change in velocity/time Change in velocity/acceleration=time So, 100km/s -70km/s/3.8m/s=t t= about 8 s; I don't agree with any of these answers. 2.) You are correct.
January 18, 2015

Chemistry
45.4g of H2O*(1 mole/18.00g)=moles of H2O moles of H2O*(moles of Fe(C2H3O2)/3 mole of H2O)=moles of Fe(C2H3O2) moles of Fe(C2H3O2)*(232.98 g/1 mole of moles of Fe(C2H3O2))= g of Fe(C2H3O2)
January 18, 2015

Chemistry
I'm not sure that I understand your question. We don't need to calculate the molarity because the volumes are the same, and will cancel out. Therefore, you can use mole amounts for each of the species; I hope this answers your question. The concentration of each ...
January 18, 2015

Chemistry---Typo
*****Correction of last part: Use this variation of the Henderson-Hasselbalch equation and solve for pH: pOH=pkb+log[BH/B] Let B=y** BH=x** pkb=-log(5.2 x 10-4) and pOH=??? Solve for pOH: After solving for pOH, solve for pH: pH+pOH=14 pH=14-pOH
January 18, 2015

Chemistry
No ICE chart is needed; you just have to look at what is going to happen when the HCl is added. HCl + CH3NH2 ------> CH3NH3^+Cl^- So, the addition of HCl will convert some of the CH3NH2 to CH3NH3^+Cl^- and decrease the amount of CH3NH2. First, figure out the amount of moles...
January 18, 2015

To Devron
My concentration was in biochemisty, but my research was done in an organometallic chemistry laboratory studying the efficacy of micruflidic devices on the determination of enantiomers generated from zirconium and niobium Lewis-acid cataylst using GC's and H NMR. So, I'...
January 18, 2015

To Devron
I saw it, and did not understand it as well, which is the reason that I left it alone after looking at your reply.
January 18, 2015

chemistry
I don't know this article by heart, nor have I ever read it. I doubt that Dr. Bob222 hasn't read nor knows this article as well. And I doubt that you will get anyone on this forum to find and access this article to check your work. Best and good luck.
January 18, 2015

Chemistry
I like that you told the student that chemistry is never dull--classic.
January 17, 2015

Chemistry
Chemistry and physics are both fun subjects. Do you need to understand math? Yes. Does it compare to physics? Yes. However, the math is more tedious than it is in chemistry, and at times, requires more steps, and requires a different type of conceptualization to apply the math...
January 17, 2015

Chemistry
I don't want to waste my time doing a lot of typing if this is not what you need.
January 17, 2015

Chemistry
This is a confusing question that is poorly worded. So, I am not sure what your professor wants you to do. The confusing part, to me, is from pH 1 to 13 with 0.4M NaOH. However, this is what I think you are suppose to do: determine the volume of 0.4M NaOH added to reach the ...
January 17, 2015

Chemistry
This is a confusing question that is poorly worded. So, I am not sure what your professor wants you to do. The confusing part, to me, is However, this is what I think you are suppose to do: determine the volume of 0.4M NaOH added to reach the equivalence point for H3PO4 and ...
January 17, 2015

Chemistry
Charlotte, It is just a simple Y vs X graph. The pH is the dependent variable and is plotted on the y-axis, and the temperature is the independent variable and is plotted on the x-axis. For example, at say 63 degrees, the pH is 8.4. You will find 63 degrees on the y-axis, and ...
January 16, 2015

Chemistry--Clarification
I should have said TRIS-HCl is added to decrease the pH, not HCl. You want a slight change in the pH of the solution, not a rapid change. Adding HCl will cause you to miss the pH by too much, and is difficult to obtain the desired pH. TRIS base by itself usually has a pH above...
January 16, 2015

Chemistry
TRIS buffers usually have a pH between 7 and 9, with TRIS having a pka value of 8.1. HCl is usually added to decrease the pH of the buffer to somewhere close to 7, which makes it a TRIS HCl buffer; it is usually only called TRIS HCl when the HCl has been added. This looks like...
January 16, 2015

Chemistry
You don't specify the pH, so know one can help you with this one.
January 16, 2015

physics
4-seconds. But if you need to see the math, here you go: Vf=Vi+at Where Vf=0m/s Vi=20m/s a=-5.0m/s and t=?? Solve for t: 0m/s=20m/s+(-5.0m/s^2)*t -20m/s=(-5.0m/s^2)*t t=-20m/s/-5.0m/s^2 t=4s
January 16, 2015

Chemistry
Thought about it some more, and this is a combustion problem. I could have saved myself some work. Dr. Bob222 is correct.
January 15, 2015

Chemistry
The way that Dr. Bob22 went about doing it could be correct, and the author of the question is assuming that the gases would combine in a combustion reaction, which is something that I did not think of when approaching this problem.
January 15, 2015

Chemistry
I have no idea if this is correct, but I'll take a stab at it. Use the ideal gas law to start, and I will have to do some assuming. I'm going to first assume that the temperature of both gases are the same, and I will also assume that I have equal quantities of each ...
January 15, 2015

physics
Thermal energy is caused by motion of? 2. molecules in solid liquid and gas phases Thermal energy is do to random motion of molecules. Only one answer choice fits that description. the density of an object with the volume of 60.0 mL and a mass f 400.0 g is Didn't do the ...
January 15, 2015

Physics (is my work correct????)
Fnet=Ft-Ff m*a=Ft-Ff 2.00kg*0.750=2.50N-Ff 1.5N=2.50N-Ff 1.5N/2.50N=Ff Ff=0.6N
January 15, 2015

Physics- Can you check my answer PLEASSE
Looks good to me.
January 15, 2015

Physics
The vertical component of the balls velocity is the following: 15m/s*Sin 30=7.5m/s The deceleration due to gravity is 9.8m/s. So, after 1s the ball will be falling back down to the ground, which eliminates the first two answer choices. Does it take a half a second for the ball...
January 15, 2015

SCIENCE/Chemistry--Clarifiication
@@Look for correction. Now, for every mole of Al(C9H6NO)3, there is 1 mole of Al^3+. i.e., 1 mole of Al=1 mole of Al(C9H6NO)3 @@0.1248g of Al(C9H6NO)3 *(1 mole/459.4317 g)= moles of Al(C9H6NO)3 moles of Al(C9H6NO)3=moles of Al^3+ moles of Al^3+*(26.98g/1 mole)= mass of Al^3+ ...
January 15, 2015

SCIENCE
Now, for every mole of Al(C9H6NO)3, there is 1 mole of Al^3+. i.e., 1 mole of Al=1 mole of Al(C9H6NO)3 Al(C9H6NO)3 *(1 mole/459.4317 g)= moles of Al(C9H6NO)3 moles of Al(C9H6NO)3=moles of Al^3+ moles of Al^3+*(26.98g/1 mole)= mass of Al^3+ in grams (mass of Al^3+ in grams/1....
January 15, 2015

physics
Fnet=Fp-Ff ma=Fp-Ff Let a= acceleration. Solve for a: 10kg*a=25N-2N a=23N/10kg a=2.3m/s^2
January 15, 2015

physics
You can use the range equation to figure this out, first, if the ball even makes it to 100m. horizontal distance=R=Vi^2*Sin2(Theta)/g Where Vi=22m/s Theta=45 and g=9.8m/s^2 Solve for R: R=(22m/s)^2*Sin2(45)/(9.8m/s^2) R=(22m/s)^2*Sin2(45)/(9.8m/s^2) R=49.39m The ball doesn'...
January 15, 2015

physics
Use the following equation; the horizontal distance is irrelevant. d=Vi+1/2at^2 Where vi=0m/s ** there is no initial velocity in the y-direction. a=g=9.8m/s^2 and t=2s Solve for d: d=0+1/2(9.8m/s^2)(2s)^2 d=19.6.m=20m
January 15, 2015

physics
You do one.
January 14, 2015

Physics---Saw Another Typo
This is the whole thing corrected; ignore the previous two post. Do you even need to know the mass of the ball? I don't know, but I think that I need to determine the initial velocity in the y-direction, first: Vf^2=Vi^2-2gd where: d=23.2m Vf=0m/s g=9.8m/s^2 Solve for Vi: ...
January 14, 2015

Physics---Oppps/Typo
For the left side of the equation g=9.8m/s^2 h=0m and v=21.32m/s **** Correction For the right side of the equation g=9.8m/s h=23.2-6m=17.2m and v=?? Solve for the v: 0J+1/2(21.32m/s)^2=(9.8m/s)*(17.2m)+1/2v^2 227.32J=168.56J+1/2v^2 227.32J-168.56J=1/2v^2 Sqrt*[2*(1458J-168....
January 14, 2015

Physics
Do you even need to know the mass of the ball? I don't know, but I think that I need to determine the initial velocity in the y-direction, first: Vf^2=Vi^2-2gd where: d=23.2m Vf=0m/s g=9.8m/s^2 Solve for Vi: Vi=Sqrt(2*9.8m/s^2*23.2m) Vi=21.32m/s Conservation of energy tell...
January 14, 2015

Biology
Its helicase.
January 14, 2015

physics
First, break down the velocity into its' horizontal and vertical components: Vx=23m/s*Cos42=17.09m/s Vy=23m/s*Sin42=15.39m/s Use the following kinematic equation: Vf=Vi+at Where Vi=15.39m/s a=g=-9.8m/s t=??? and Vf=0m/s ***When the football reaches it's peak, the ...
January 14, 2015

science
I answered this question, and the second is incomplete. There are three types of progeny in the F1 generation, and the question doesn't specify which progeny.
January 13, 2015

Science
I should have said 75%, but the second question still can not be answered.
January 13, 2015

Science
Let: D=normal and d=recessive P1: DD x Dd F1: 1DD : 2Dd : 1dd 66% should have normal hearing. The second question is incomplete.
January 13, 2015

chemistry
Use the gas law and do some conversion: PV=nRT Where P=99.3kpa V=455mL=0.455L R=0.0821 L·atm/mol·K T=24.0 C and n=??? Convert kpa to atm and C to K 1Atm = 101.325 kPa So, 99.3 kPa*(1 atm/101.325kPa)= 0.980 atm K=C + 273 So, 24.0 + 273=297K Solve for n: n=PV/RT n...
January 13, 2015

Chemistry--Typo
For your ***Last question, you have to determine the limiting reagent: 10.0g Fe*(1 mole/55.845g)= moles of Fe 2.00g O2*(1 mole/32.00g)= moles of O2 Eyeballing it, I think O2 is the limiting reagent. Proceed as you would for the second problem.
January 13, 2015

Chemistry
This is just basic stoichiometry. From the reaction, this is the basic information that you will need: 4 moles of Fe = -1652 kJ 3 moles of O2 = -1652 kJ and 2 moles of Fe2O3= -1652 kJ So, for your first question: 4 moles of Fe = -1652 kJ For your second question: 1.00 mol ...
January 13, 2015

physics
c=360m/s I gave you the speed of light and not sound.
January 13, 2015

physics
I didn't know that you answered the question.
January 13, 2015

physics
Use this simplified equation, which is short and dirty method to determine the answer to your question: f=v/c*(f') Where v=-40mph=-17.88m/s c=3 x 10^8 m/s f'=1,000Hz Just eyeballing the numbers, you should see a lower frequency, since v is negative.
January 13, 2015

Chemistry
I posted an answer/solution to another problem that you had. I think that it explains the concept of what you are suppose to be doing a little bit better, or it can be used as an additional resource to help you with similar problems.
January 13, 2015

Chemistry
No, its being oxidized. It has a lower reduction potential. These are the half reactions from a standard half reaction chart: I2 + 2e- -> 2I- ClO- + 2e- -> Cl- **I2 is being oxidized, so you need to reverse the reaction: 2I^- <- - -> I2 + 2e ClO- + 2e- -> Cl- ...
January 13, 2015

Chemistry
I thought I posted a response for this a while ago, but when I looked back at my browser, I saw that I didn't. Also, I omitted ^2- charge on the O, which Dr.Bob222 didn't do.
January 13, 2015

Chemistry
2 Mg (s) + O2 (g) -> 2 MgO (s) You have to look up the half potentials for each, and determine which is being reduced and which one is being oxidized. The reduction potential for O2 is higher, so Mg loses electrons. This means you have to reverse the reaction that you see ...
January 13, 2015

Chemistry (Chromatography)
In the case of chromatography, like attracts like. So, the more polar compound will elute slower than the compounds not as polar because the plate is polar. Highest Retention Time: X > Y > Z :Lowest Retention Time In the case of reverse phase chromatography, it is reversed.
January 13, 2015

Chemistry (Chromatography)
This looks like cation chromatography. The elution order is determined by the charge of the ions: the more positively charged the ion, the more it will be retained (i.e., Fe3+ will have the highest retention time and Na^+ will have lowest, due to it being lighter than Ag^+).
January 13, 2015

Chemistry
Look at your first post; this problem is almost identical.
January 13, 2015

Chemistry
Combustion reactions always follow this general reaction: CxHy + O2 -----> CO2 + H2O Plug in Octane into the the reaction and then balance: C8H18 + O2 -----> CO2 + H2O 2 C8H18 + 25 O2 -----> 16 CO2 + 18 H2O Just eyeballing it, octane is the limiting reagent. ****To ...
January 13, 2015

Chemistry
Look at one of your previous post to see if you can figure this problem out. Post your work if you get stuck.
January 13, 2015

Chemistry
The reaction is as followed: Zn + Sn(NO3)2 --> Sn + Zn(NO3)2 Convert 0.750M Sn(NO3)2 to moles: Molarity (M)= moles/volume (L) Molarity*Volume (L)=moles moles of Sn(NO3)2=0.750M*0.150L This is similar to the limiting reagent problem. Proceed as you would do for the limiting ...
January 13, 2015

Chemistry
PbCO3 ---> PbO + CO2 First, calculate theoretical yield: 5.00g*(1 mole/267.21 g) = moles of PbCO3 moles of PbCO3=moles of PbO moles of PbO*(223.20 g/mole)= mass of PbO mass of PbO=theoretical yield (1.52g/theoretical yield)*100= % Yield
January 13, 2015

Chemistry (Acid-Base)
In solution: HA <----> H^+ +A^- Ka=[H^+][A^-]/[HA] I've never heard the question asked this way either, but I think for A and B, the author of the question wants to know if A^-/H^+ or HA are the dominant species. The lower the pH, the more A^- you have; the higher ...
January 12, 2015

chemistry
Looks good to me.
January 10, 2015

Chemistry
Dr. Bob222 is correct: the setups are more or less the same. I just corrected my typo so that you did not get confused looking at what he wrote and looking at what I wrote.
January 9, 2015

Chemistry
I didn't think that this reaction would occur, but they way that I went about doing it is how you would solve it. The reaction, balanced is: 2 Al(NO3)3 + 3 K2SO4 ---> Al2(SO4)3 + 6 KSO4 and not 2 Al(NO3)3 + 3 K2SO4 ---> Al2(SO4)3 + 6 K2SO4 I had a typo.
January 9, 2015

Chemistry
Balance the reaction: 2 Al(NO3)3 + 3 K2SO4 ---> Al2(SO4)3 + 6 K2SO4 Convert mass of Al(NO3)3 to moles: 4.26kg of Al(NO3)3 = 4.26 x 10^3 g of Al(NO3)3 4.26 x 10^3 g of Al(NO3)3 *(1 mole/212.996g)= moles of Al(NO3)3 moles of Al(NO3)3*(1 mole of Al2(SO4)3/2 moles of Al(NO3)3...
January 9, 2015

Physics
F=Fx+Fy Two equations: 1.) Fx=F*Sin35=m*v^2/r 2.) Fy=F*Cos35-Fg Fy=F*Cos35-m*g Solve equation 2 for F: m*g=F*Cos35 Solving for F: mg/Cos35=F Plug 2 into 1 and simplify: (mg/Cos35)*Sin35=m*v^2/r mg*Tan35=m*v^2/r Masses cancel: g*Tan35=v^2/r Solve for v: sqrt[r*(g*Tan35)]=v Use ...
January 8, 2015

chemistry
The units given are in mol/L or M Solve for moles: 0.25mol/L= x moles/1.75L Solve for x moles: x moles=1.75L*(0.25mol/L) x moles * molecular weight of sodium phosphate (163.94 g/mol)= mass or Sodium Phosphate No more than two significant figures in answer.
January 8, 2015

physics
1/2mv^2=mgh The masses are the same, so they cancel out leaving the above relationship: 1/2v^2=gh Solve for v: v=sqrt*(2gh) where g=9.8m/s^2 and h=0.8m
January 3, 2015

Biology
C is not correct. If the answer choice was C, it would be DNA replication, not transcription, so you can eliminate this answer choice. DNA does not unwind from both ends, nor does it open up all of the way, so you can eliminate answer choice A and B as well. The best answer ...
December 31, 2014

Biology
I agree with your answer choice.
December 31, 2014

biology
I believe that the answer is interphase, but I am not sure about the question. Google interphase and the cell cycle and interphase and meiosis.
December 30, 2014

Physics
Two equations: KE=1/2mv^2 and PE=1/2kx^2 Where: PE=potential energy KE=Kinetic energy m=mass of the block v=velocity of the block k=spring constant and x=0m-0.35m=-0.35m Set both equations equal together and solve for k: 1/2mv^2=-1/2kx^2 k=mv^2/x^2 k=[2.0kg*(2.5m/s)^2]/(0.35m...
December 30, 2014

bio please help Ms sue
A.) DNA Polymerase B.) Replication C.) Semi conservative
May 26, 2014

Science
I will give you a hint: friction acts against motion.
May 20, 2014

Physics
Horizontal=7.5N*Cos(40) Vertical=7.5N*Sin(40)
May 20, 2014

Physics
F of spring=kx Where: x=0.200m and F=800N Solve for k: k=800/0.200m k=4,000 a.) PE=1/2kx^2 PE=1/2(4,000)(0.200m) PE=400J b.) PE=1/2kx^2 PE=1/2(4,000)(0.0500m) PE=100J ****Check my math.
May 20, 2014

biology
A.) follicle stimulating I am not sure about B, but I believe that it is referring to the LH surge, so I would go with luteinizing hormone or LH.
May 20, 2014

Science
You are correct. Newton's third law.
May 20, 2014

biology
sexual reproduction
May 19, 2014

please help
Auditory.
May 18, 2014

Human Biology please help
I had to use a resource for this one. The first answer I believe is bulb, and the second answer I believe is limbic. Best and good luck.
May 18, 2014

Chemistry
HCl is a strong acid, so yes. The concentration of HCl is equivalent to the concentration of H3O^+ in solution. 10^-14=[H3O^+][OH^-] [H3O^+]= 4.72 X 10^-9 M [OH^-]=10^-14/4.72 X 10^-9 M
May 18, 2014

Human Biology please help
Check your subsequent post.
May 18, 2014

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