Devron

Most popular questions and responses by Devron
1. Math Check

For each integer n>1, let A(n) denote the sum of the integers from 1 to n. For example, A(100)=1+2+3+ +100=5,050. What is the value of A(200)? A.)10,100 B.)15,050 C.)15,150 D.)20,100 E.)21,500 I know that the best answer choice is D, but the explanation

2. Dr. Bobb222

When you get a chance: If the pure liquid vapor pressure of benzene is 155 torr and the pure liquid vapor pressure of chloroform is 333 torr, then what is the total vapor pressure at 30°C of a solution of 9.26 g of benzene (C6H6) and 4.26 g of chloroform

3. Dr.Bob222 Chem

I believe that you are correct because you have more experience in G-chem then I have. But how does doubling the reaction rate double the k value? Isn't k just a constant for a particular reaction?

4. 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

5. Dr. Bob222 G-Chem

I agree with 0.0918 mols C and 0.137 mols H but not the formula. 0.137/0.0918 = about 1.5; is that C2H3? And the balanced equation is 4C2H3 + 11O2 ==> 8CO2 + 6H2O I've not heard of C2H3? Okay, I have never heard ofC2H3 as well, so I had to take the number

6. Math Check

Is the following statement true: (x^4+6x^2+9)=x^2+3

7. Chemistry Dr.Bob222==> Take a Look

what is this compound, it has a mf of c6h12o i. imgur. com/gCgw0Hi. png What may be the structure from the IR and H NMR data? This question is bugging me.

1. Biology

Heat: PCR reactions are heat intensive processes, which require a polymerase that is able to withstand the heat. Taq polymerase is what is usually used in PCR reactions.

posted on April 27, 2018
2. Math Check

Thanks

posted on August 16, 2015
3. Math Check

Thanks, so this falls under induction by reasoning, if I'm not mistaken?

posted on August 15, 2015
4. math

That is correct. 200 + [0.15 * (2,500-1,000)] = ?

posted on August 15, 2015
5. math

200 + (0.15 * 2,500) = ?

posted on August 15, 2015
6. Biology

a.The monomers that make up a protein vary whereas the monomers that make up a complex carbohydrate are all the same. --This is mostly true, but I would suggest that you give a couple of examples, such as fatty acids, or a short truncated protein.

posted on August 15, 2015
7. Chemistry

Things to keep in mind: Molarity=Moles/Volume (L) HNO3=63.01g/mol 69.5%=0.695 and 1cm^3=1mL=10^-3L Convert Density from g/cm^3 to g/L: 1.42g/cm3*(1cm^3/10^-3L)=1420g/L Calculate the amount of pure acid: 1.420g/L*(0.695)= mass of pure HNO3 in g/L Since the

posted on August 1, 2015
8. Math Check

Got it. I was totally overthinking this.

posted on July 22, 2015
9. Math Check

I know that, which is why I thought the answer was no, but then I was told that the answer was yes. I couldn't simplify nor reason it any further than what I have submitted. If you can show how to do it, it would be greatly appreciated; the problem is kind

posted on July 22, 2015
10. Math Check

I thought is was no. When asked this question by someone, I could not get the left side to look like the right. x^2+ x(6)^1/2+3=x^2 +3 How does this simplify any further?

posted on July 22, 2015
11. Math Check

Is the following statement true: (x^4+6x^2+9)^1/2=x^2+3

posted on July 22, 2015
12. 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,

posted on May 8, 2015
13. 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.

posted on May 2, 2015
14. 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

posted on April 27, 2015
15. 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.

posted on April 27, 2015
16. Chemistry 2

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

posted on April 25, 2015
17. 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=???

posted on April 25, 2015
18. 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

posted on April 25, 2015
19. Chemistry 2

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

posted on April 25, 2015
20. Chemistry 2

DeltaG=DeltaH-DeltaS*T Where DeltaH=-220kJ/mol DeltaS=-136.76kJ/K T=426K and Delta=????

posted on April 25, 2015
21. 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

posted on April 23, 2015
22. 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

posted on April 23, 2015
23. Chem

I think that you need more information then what you are providing for someone to be of any help.

posted on April 23, 2015
24. 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)]

posted on April 23, 2015
25. 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

posted on April 21, 2015
26. 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

posted on April 21, 2015
27. PHYSICS

I wouldn't know how to solve the problem either because you are missing some information.

posted on April 21, 2015
28. General Physics

V3=9.82m/s

posted on April 19, 2015
29. 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,

posted on April 18, 2015
30. 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

posted on April 18, 2015
31. chemistry

I meant to say that the answer to part 2 isn't the answer to part 1.

posted on April 18, 2015
32. 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

posted on April 18, 2015
33. 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

posted on April 18, 2015
34. 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

posted on April 18, 2015
35. 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

posted on April 18, 2015
36. 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)=???

posted on April 18, 2015
37. 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.

posted on April 17, 2015
38. 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)

posted on April 17, 2015
39. 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

posted on April 17, 2015

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.

posted on April 16, 2015
41. 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)

posted on April 16, 2015
42. 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]

posted on April 16, 2015
43. 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.

posted on April 16, 2015
44. 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

posted on April 15, 2015
45. Scientific Notation

3^4=??????

posted on April 15, 2015
46. 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

posted on April 15, 2015
47. 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

posted on April 14, 2015
48. 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.

posted on April 13, 2015
49. Biology

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

posted on April 13, 2015
50. 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.

posted on April 12, 2015
51. 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

posted on April 9, 2015
52. 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

posted on April 9, 2015
53. 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

posted on April 6, 2015
54. 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.

posted on April 4, 2015
55. Cara-Chem

Remember, pH=-log[H^+] so, pH=-log[x]

posted on April 3, 2015
56. 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

posted on April 3, 2015
57. 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

posted on April 2, 2015
58. 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.

posted on April 1, 2015
59. 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

posted on April 1, 2015
60. 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

posted on March 31, 2015
61. 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.

posted on March 30, 2015
62. 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.)

posted on February 19, 2015
63. 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,

posted on February 12, 2015
64. 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

posted on February 11, 2015
65. chemistry

I meant to say solve for Ka and not x.

posted on January 28, 2015
66. chemistry

Typed something out of habit. plug in the value for x and solve Ka: I apologize about that.

posted on January 28, 2015
67. 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:

posted on January 28, 2015
68. chemistry

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

posted on January 28, 2015
69. chemistry

I've told you enough.

posted on January 28, 2015
70. 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

posted on January 28, 2015
71. 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

posted on January 28, 2015
72. 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.

posted on January 28, 2015
73. Chemistry

You have to do your own work. Maybe just post what you think it is and why.

posted on January 28, 2015
74. chemistry

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

posted on January 28, 2015
75. 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.

posted on January 28, 2015
76. Chemistry

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

posted on January 28, 2015
77. 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

posted on January 22, 2015
78. Chemistry

posted on January 21, 2015
79. 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,

posted on January 21, 2015
80. Chemistry

Density=mass/volume Density of Bromine=586g/188 mL ***Answer contains 3-significant figures

posted on January 21, 2015
81. 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

posted on January 21, 2015
82. 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:

posted on January 20, 2015
83. SCIENCE

Initial velocity=time*deceleration=4s*9.8m/s^2=39.2m/s

posted on January 19, 2015
84. 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

posted on January 19, 2015
85. 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.

posted on January 18, 2015
86. 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

posted on January 18, 2015
87. 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.

posted on January 18, 2015
88. 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)

posted on January 18, 2015
89. Chemistry

*****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

posted on January 18, 2015
90. 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

posted on January 18, 2015
91. Chemistry

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

posted on January 18, 2015
92. 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

posted on January 18, 2015
93. 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

posted on January 18, 2015