Wednesday
July 8, 2015

Posts by Devron


Total # Posts: 1,040

Science
The pull of electrons is the main reason. The pull of the lone electron of hydrogen by oxygen shortens bond length; this is easily seen by looking at the electronegativity difference between oxygen and hydrogen. Although alcohol also contains a OH bond, the OH is bonded to a ...
May 8, 2015

Organic chemistry
I'm not sure, but I do not think that a reaction would occur. ALCl3 usually acts as a catalyst, and would just form an ionic bond with the oxygen on the carbonyl of the compound; there isn't another reactant to form some other compound.
April 27, 2015

chemistry
First, determine the molarity of KHC2O4: 0.717g*(1 mol/128.12g)=moles of KHC2O4 18.47 mL=0.01847L Molarity of KHC2O4=moles of KHC2O4/0.01847L The reaction is a 1 mole to 1 mole reaction. Therefore, moles of KHC2O4=moles of NaOH. So, Molarity of KHC2O4=Molarity of NaOH ***...
April 27, 2015

Physics
I hope someone validates this answer since I don't play around with these concepts all of the time, but here is my response. The force that the block exerts down the ramp is the following: Fof block=mg*Sin(30) Fof block=(4.0kg)*(9.8m/s^2)*(0.5)=19.6N Force of Static ...
April 25, 2015

Chemistry 2--Dr.Bob222
I initially made the same mistake, which confused me a little. I reread the question and saw that the questioner and I, both, may have initially overthought the question. --Best
April 25, 2015

Chemistry 2
To the questioner: I apologize about the typos. I meant to say solve for Delta*G and not just Delta. My post should have said the following: DeltaG=DeltaH-DeltaS*T Where DeltaH=-220kJ/mol DeltaS=-136.76J/K=-0.13676kJ/K T=426K and DeltaG=???
April 25, 2015

Chemistry 2---Dr.Bob222
The key part of the equation states that ASSUME that DeltaS and DeltaH DOESN'T Change much, meaning that it is safe to plug and chug. ***To the questioner: change -136.76J/K to kJ, which should be -0.13676kJ/K
April 25, 2015

Chemistry 2
DeltaG=DeltaH-DeltaS*T Where DeltaH=-220kJ/mol DeltaS=-136.76kJ/K T=426K and Delta=????
April 25, 2015

Ap chem
It would increase the rate of the reaction. Looking at the equation should allow you to notice this. In general there are three factors that can affect the rate of a reaction: 1.) reactant concentrations 2.) catalysts 3.) temperature
April 23, 2015

Chem
You can use an equation or you could just do it intuitively; I choose to do this one intuitively. 1.0mg =12 hrs 2.0mg=10 hrs 4.0mg=8 hrs 8.0mg= 6hrs 16.0mg=4hrs 32.0mg=2hr 64.0mg=0hrs So, you will initially need 64.0mg of 55Cr to have a minimum of 1.0mg after 12-hours.
April 23, 2015

Chem
I think that you need more information then what you are providing for someone to be of any help.
April 23, 2015

chemistry - kinetics
Use the following equation: Ln(k2/k1)=Ea/R[(1/T1)-(1/T2)] Where k1=0.0796 M−1*s−1 k2=0.0815 M−1*s−1 R=8.314 J/mol K. T1=273+737=1010K T2=273+947=1220K and Ea=???? Solve for Ea: Ea={R*[Ln(k1/k2)]}/[(1/T1)-(1/T2)]
April 23, 2015

science
I just noticed that I messed up. D is an answer that shouldn't have eliminated, and to be honest, I believe that it is the best answer choice.
April 21, 2015

science
The purpose of the endocrine system, which secretes hormones, is to control growth and development. Which of these answer choices best fits that description? I will eliminate two answers for you -- answer choices C and D-- to give you a 50/50 chance
April 21, 2015

PHYSICS
I apologize about that. I should have thought about it for more than 3 seconds. The answer is in the directions: the puck travels only one-half the distance Conservation of mechanical energy says that Work=kinetic energy F*d=1/2mv^2 m*a*d=1/2mv^2 masses are the same and cancel...
April 21, 2015

PHYSICS
I wouldn't know how to solve the problem either because you are missing some information.
April 21, 2015

General Physics--Typo
V3=9.82m/s
April 18, 2015

General Physics
Use the following relationship: M1V1 +M2V2= M3V3 Where M1=5.00kg V1=12.0m/s M2=6.00kg V2=8.00m/s M3=5.00kg+6.00kg=11.00kg and V3=??? Solve for V3: (5.00kg*12.0m/s)+(6.00kg*8.00m/s)=(11.00kg)V3 V3=108kg*m/s/11.00kg V3=9.82 N s
April 18, 2015

Heat
The same way that I showed you how to do the other one, but just convert 8.08g of H2 to moles: 8.08g of H2*(1 mole/2.02g)=??? moles
April 18, 2015

Enthalpy
Assuming O2 is in excess: 2 moles of MgO=2 moles of Mg=1 moles of O2 So, 4 moles of Mg*(-1203kJ/2 moles of Mg)=???
April 18, 2015

Chem
14 H^+ + 2 Mn^2+ + 5 NaBiO3 --->5 Bi^3+ + 2 MnO4^- + 5 Na^+ + 7 H2O Here is the the balanced reaction (Oxidation and Reduction) 34.2MgSO4=0.0342g of MgSO4 0.0342g of MgSO4*(1 mole/120.366 g)= moles of MgSO4 The equation shows that 2 MnSO4 moles=5 moles of NaBiO3 So, moles ...
April 18, 2015

Chemistry
I wouldn't tackled it this way, and you are free to not use what I am telling you because I can not be 100% positive about the answer. However, I would go this route: q=mct where q=44,000 kJ=4.4 x 10^4 kJ=4.4 x 10^7 J c=8.37 J/g*C t=110 C-95 C=15 C and m=??? Solve for m: m...
April 18, 2015

chemistry
I am not sure, and someone can come along after I am done and check what I am telling you, but I believe you are missing some information like the temperature change. The question seems to be incomplete.
April 17, 2015

chemistry
I didn't fully read this question; I was wondering what Dr.Bob222 did. He is correct: 4.0mL of of Cl2 will be used meaning that there will be no Cl2 left at the end of the reaction, but 3.0mL of H2 gas will be left after the reaction is complete. However, I'm not sure ...
April 17, 2015

chemistry
The reaction is as followed: H2 + Cl2 ----> 2HCl You can treat this as a limiting reagent problem, where Cl2 is the limiting reagent. 1 mole of Cl2=2 moles of HCl or 1mL of Cl2= 2 mL of HCl 4.0mL of Cl2*(2 mL of HCl/Cl2)= 8mL of HCl (g)
April 17, 2015

chemistry-typo
I meant to say that the answer to part 2 isn't the answer to part 1.
April 17, 2015

chemistry
I agree with DrBob222 and then I don't agree with him: I agree that the 2nd part that he gave you in his last point is correct, but the answer to part 2 isn't the answer to part 2. I agree that it should because adding these two concentrations of acid together doesn&#...
April 17, 2015

chemistry
The first question asks for the MOLARITY of the solution after adding the two together; the second question asks for the molarity using the DENSITY. You will get two different answers. Also, the acid that is given is H2SO4 and not HCl. The molecular weight that Drbob222 used ...
April 17, 2015

BIO HELP PLEASE!!!
Because the virus doesn't affect the rest of the cell types that it targets until a stress or an environmental factor causes reproduction and lysis; it remains dormant until it receives it's que to begin.
April 16, 2015

Chemistry
First, convert mL to L: 20mL=0.0200L and 30.0mL=0.0300L Solve for moles: M=moles/Volume (L) so, moles=M*Volume(L) New Molarity=Total moles/Total Volume M=[(0.0200L)*(3.0 M)+(0.0300L)*(2.0M)]/(0.0200L+0.0300L)
April 16, 2015

chemistry
HCl is a strong acid so, determine the pH: pH=-log[HCl] pH+pOH=14 14-pH=pOH Since pOH=-log[OH^-] 10^-(pOH)=[OH]
April 16, 2015

science
I don't see questions 1 and 2, but if you are referring to questions 4 and 5, then I believe that answer choice A is the best answer choice for number 4 and I agree with your answer choice for number five as well.
April 16, 2015

chemistry
Write out the reaction: ZN + 2 HCl --> ZNCl2 + H2 Covert g of H2 gas produced to moles: 0.15g of H2*(1 mole/2.016g)= moles of H2 moles of H2=moles of Zn moles of Zn*(65.37g/mol)= g of Zn Answer contains two significant figures Conversely, this could have just been combined ...
April 15, 2015

Scientific Notation
3^4=??????
April 15, 2015

Chemistry
if the volumes of the weak acid and its conjugate base are equal than the pH=pka of the solution. You know this by looking at the Henderson–Hasselbalch equation. pH=pka+log[A^-]/[HA] Where A^-=NaNO2 and HA= HNO2 Since the concentrations are equal, the above equation ...
April 15, 2015

biology
ATP is the energy source for all cells, so that answer is ruled out. C is also ruled out because although it is a neurotransmitter, it is activated to usually cause an emotional response; Glycine is one of the simple amino acids that doesn't act on taste buds -- as far as ...
April 13, 2015

biology
The control of skeletal muscle is voluntary, which means that you can control its' movement. However, the movement of blood through the body is not voluntary, which means you can not control it. So no, A can not be the answer.
April 13, 2015

Biology
No, that is why they are called memory B-cells. They remember that specific infection and respond accordingly.
April 13, 2015

Chemistry
Used the following equation and plug in a couple of variables for T and see what you get. ΔG=ΔH−TΔS Remember, if ΔG is negative then the reaction is spontaneous, if positive, than the reaction is not spontaneous, and if equal to 0 is at equilibrium.
April 12, 2015

Chemistry
I am not sure I understand what you are saying, but the number that number seems to be the Ka value for phosphoric acid. pH=pka+log[A^-/HA] let pka=-log[Ka] Ka=6.2 x 10^-8 pka=-log[Ka]=7.21 A^-=0.335 HA=0.335 To help you out a little bit: The concentrations are equal, so the ...
April 9, 2015

Chem
0.750g of MgCl2*(1 mol/95.211g)=0.007877 mol of MgCl2 *****1 mol of MgCl2=2 moles of AgCl This is the key and is where your error lies. 0.007877 mol of MgCl2*(2 mol of AgCl/MgCl2)=0.01575 moles of AgCl 0.01575 moles of AgCl*(143.32 g/mol)=2.26g of AgCl Best
April 9, 2015

Biology
Cross it with a wrinkled seed. rr=wrinkled. Rr x rr Progeny: 1 Rr 1 rr RR x rr Progeny will all be Rr and will all be Round
April 6, 2015

Chemistry
Use the gas law equation and solve for n (moles): PV=nRT Where P=3 atm V=5.00L R= 0.0821 liter·atm/mol·K T=292K and n=??? Solve for n: n=PV/RT n*39.95g/mol=mass of gas ***You can perform the rest.
April 4, 2015

Cara-Chem
Remember, pH=-log[H^+] so, pH=-log[x]
April 3, 2015

Cara-Chem
I made a bobo, which may lead to some confusion. Here is my post revised: You don't need it. Just calculate the new molarity of the acid after addition of NaOH, and then determine the molarity of the acid in solution. How many moles of propionic acid are left after ...
April 3, 2015

Chemistry
I do apologize about that. I totally forgot about the salt. Ignore the x for the salt in the setup that Dr. bob222 gave you because we are assuming that dissociation is small and solve for x. When I gave you the setup, I ignored the x in the denominator assuming dissociation ...
April 2, 2015

Chemistry
You don't need it. Just calculate the new molarity of the acid after addition of NaOH, and then determine the molarity of the acid in solution. How many moles of propionic acid are left after addition, of the strong base? In this case, Molarity=moles 1.29 x 10^-2 M=1.29 x ...
April 2, 2015

Chemistry
I'm going to assume that this is mass/volume percent: m/v%=(g/mL)*100 6.0%=(x g/50mL)*100 (6.0/100)*50=x g Solve for x g Which should be 3g, I believe.
April 1, 2015

chemistry
HNO3 is a strong acid, so this is fairly straight forward question. Calculate the new molarity of the acid after being mixed with H2O: 0.01M*0.005L= moles of HNO3. moles of HNO3/(0.005L+0.05L)= Molarity of HNO3 after addition of water. Since this is a strong acid, you can just...
April 1, 2015

chemistry
You need to pay attention to your units. The temperature for heat capacity is in given with C not K. You have to use C as temperature and not K. Also, I have no idea what the problem is asking; all I see is numbers, so I really can't check, nor can anyone else.
March 30, 2015

Chemistry
Check the units. That is where the error is. q=mct where m=10.0kg=10,000g or 10 x 10^3g c=0.385 J/g*C and T=65 C - 25 C=40 C q=(10,000g)(0.385 J/g*C)(40 C) q=15.4 x 10^4 J We agree, but I have 154,000J and not KJ. You have to convert 154,000J to KJ. 154,000J =15.4 x 10^1 KJ= ...
March 30, 2015

physics
a.) m1v1+m2v2=m3v3 Let: m1=1300g=1.3kg v1=0m/s m2=39g=0.039kg v2=290m/s m3=1.339kg *** addition of m1 and m2 and v3=??? Solve for v3: (1.3kg+0)+(0.039kg+290m/s)=(1.339kg)v3 v3=[(1.3kg+0)+(0.039kg+290m/s)]/1.339kg v3=1.3+11.31/1.339 v3=9.41m/s b.) Fnet=F(block)-F(friction) Let ...
February 19, 2015

Organic Chem
The answer may be answer choice B. Answer choice A, in my opinion, is the best answer choice. However, adding more benzene would DECREASE the amount of undesirable side products, but would NOT prevent it. Adding more benzene would not solve the problem, but it would help.
February 11, 2015

Organic Chem
I believe the best answer choice is A. Using more Benzene wouldn't do anything to prevent the formation of undesirable side products. Distillation will remove H2O and wouldn't do anything as well; I do not believe that H2O will react with Toluene, but it will react ...
February 11, 2015

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

  1. Pages:
  2. 1
  3. 2
  4. 3
  5. 4
  6. 5
  7. 6
  8. 7
  9. 8
  10. 9
  11. 10
  12. 11
  13. Next>>

Members