# ~christina~

Popular questions and responses by ~christina~
1. ## science(chem)

I synthesized Nylon in my lab for organic chem. I need help figuring out the theoretical yield so I can compare it to my product that I synthesized. I looked up the reaction online on Google by typing in "Synthesis of adipoyl chloride and nylon 6.6." I

2. ## Physics => speed of sound variation

The speed of sound in air (m/s) depends on temperature according to aprox expression of v= 331.5 + 0.607 Tc Tc= temp in celcius In dry air, temperature decreases about 1deg celcius for every 150m rise in altitude. a) assume the change is constant up to

3. ## graphing

Q: How could the function y=3t^2 +4 be plotted on a cartesian graph to produce a straight line? What would be the numerical values of the slope and the intercept of the line? For this it's explained in the lab book for physics as if the function is y=mx+b

4. ## science

A major motor company displays a die-cast model of its first automobile, made from 9.35kg of iron. To celebrate its one-hundreth year in business, a worker will recast the model in gold from the original dies. What mass of gold is needed to make the new

5. ## science

Do experimental measurements give the true value of a physical quantity? explain. ~I say no it doesn't. But why that is is up to debate on my part. I think that it doesn't give the true value because there is always a source of error and also varying

6. ## Significant figures

How would I go and express these numbers with 3 significant figures in normal notation? a)15.08 b)1444 c)83,909 d)0.524 e)0.0254 for d and e aren't they already with 3 significant figures and also in normal notation? for a, b, and c I can't figure out what

7. ## science(chemistry) -Q for Dr.Bob

solvent layer: 1 solid precipitate: no I ran the solvent layer I got in my unknown in the GC and I had sharp peaks in the beginning but at about 4 min on the polar column, I got a broad peak that tailed off considerably. question is, Is it water? I'm not

8. ## Forced Oscillation - drwls => I need your help =)

A 2.00kg object attatched to a spring moves without friction and is driven by an external force given by F= (3.00N)sin(2pi*t) The force constant of the spring is 20N/m. Determine a) period b) amplitude of motion a)T= 2pi/omega T= 2pi/ 2pi= 1s b)A= (Fo/m)/

9. ## Physics (When will Kathy overtake Stan if )

Kathy has a sports car that can accelerate at the rate of 4.90m/s^2. She races with Stan. Both cars start from rest but experienced Stan leaves starting line 1.00s before her. Stan moves with a constant aceleration of 3.90m/s^2 and Kathy maintains an

10. ## Physics, Calculus(alot of stuff together)= HELP!!

A rod extending between x=0 and x= 14.0cm has a uniform cross- sectional area A= 9.00cm^2. It is made from a continuously changing alloy of metals so that along it's length it's density changes steadily from 2.70g/cm^3 to 19.3g/cm^3. a) Identify the

11. ## American Lit => Ms.Sue (Poetry analysis help)

Poem "for rosa parks" And how was this soft-voiced woman to know that this was "No" in answer to the command to rise would signal the begining of the time of walking Soft the word like the closing of some aweful book, a too-long story with no pauses for

12. ## science(chem)

For the reaction: acetic acid (2g) + Isopentyl alcohol (0.9g) => Isopently acetate(1.15g)+ H2O I'm suposed to determine the limiting reagent, theoretical yield and percent yield from this reaction but the reaction was given as a picture... I'm not sure

13. ## Physics Concept

2 cars are moving in same direction in parallel lanes along a highway. At some instant velocity of car A exceeds car A exceeds the velocity of car B. Does that mean that the acceleration of A is greater than car B? Explain. ~Well I would say yes but is it

14. ## science(chem) Dr.Bob Question from before

I'm doing an experiment and I'm supposed to have neutral basic and acid samples of solution. I just wanted to make sure that I knew which was which. (If I'm incorrect, please correct me) Acid: 0.7ml 10% H2SO4 + 0.7ml 10% Na2WO4(sodium tungstate) Basic:

15. ## Photography club

I was thinking about how clubs get started in college in the first place. For example there is a club for different ethinicities. How do these become "clubs"? I would think someone would have to take an interest in specific things first of all. But is this

16. ## science(chem) Dr.Bob-> need help on this long lab

For 1 part of the lab I: prepare 4-Bromo-2-chloro-6-iodoaniline I dissolve 250mg recrystallized 4- Bromo-2-chloro-6-iodoaniline in 4ml of glacial acetic acid in 25ml erlenmyer flask and add 1ml water to the mixture. Then I prepare a solution of 250mg

17. ## Physics

A person can lift 45 kg ( aprox 100lb). Using specific gravity as 10.17 How many cubic meters of the metal could the person lift in a) air ? b) water ? c) in water ? Thanks

18. ## sand bath (chem)

what are disadvantages and advantages of using a sand bath to heat something in chem?

2 blocks are connected by a rope of negligible mass are being dragged by a horizontal force. Suppose F= 68.0N, m1= 12.0kg, m2= 18.0kg and the coefficient of kinetic friction between each block and the surface is 0.100. a.) draw free body diagram for each

20. ## science (physics) Need to solve this today please

(a) Express the vectors A, B, and C in the figure below in terms of unit vectors. (b) Use unit vector notation to find the vectors R = A + B + C and S = C – A – B. (c) What are the magnitude and directions of vectors R and S? Well the picture goes and

21. ## Physics but could be just Math ?????

A creature moves at a speed of 5.00 furlongs per fortnight (not a very common unit of speed). Given that 1 furlong= 220 yards and 1 fortnight= 14 days determine the speed of the creature in m/s. ~ for this question: know: 5 furlongs/ fortnight 1fortnight=

22. ## science(chem)

statement from my text says: "like disolves like", This rule is most commonly applied to polar and nonpolar compounds. According to this rule, a polar solvent will dissolve polar(or ionic) compounds and non polar solven will dissolve nonpolar compounds.

23. ## chemistry

how would I determine the hybridization of the carbon atom if it has 3 single bonds with hydrogen and no free electrons? Do I draw this out??

24. ## chemistry

I have a question about m-Phenylenediamine. Is m-Phenylenediamine the same as m-Phenylenediamine hydrochloride? I apparently have to use the latter for a chemical test but we only have a bottle that is labeled as the former. Is it okay to use that and just

25. ## chemistry- Dr.Bob, can you help me out please?

If I had two unknown chemicals (in solid form) mixed together, how could I go about identifying the individual components of the mixture? Is it possible, by UV, IR, GC, or HPLC? The problem I have is that with: GC= sample is destroyed & if you don't know

not understanding how to do this. A certain storm cloud has a potential of 1.00x10^8 V relative to the tree. If during a lightning storm, 50C of a charge is transfered through this potential differnce and 1.00% of the energy is absorbed by the tree, how

27. ## science(chem)

NaClO3 + H2O + HCl=> what form is the Cl in ? I know that a gas is formed but the reaction that I did also had Cl reacting with the reactants so I'm not sure in what form of Cl did my reactant react with the product of the above reaction. Thanks

28. ## physics => really need help on 2 problems (#1)

A house has well insulated walls. It contains a vol of 100m^3 of air at 300K a) calculate the E required to increase the T of the diatomic gas by 1.00C b) If this E could be used to lift an object of mass m through a height of 2.00m what is the mass of m?

Based on the question topic posted by Britney below titled:In your opinion (your answer to this reminded me of something) (I posted the same thing there but I thought it was improper to piggyback on that post so I posted this under a new topic) I don't

30. ## Physics..=> drwls - I need your help

I need help seeing if my thoughts are correct and how to do some things. Block 1 of mass 0.200 kg is sliding to the right over a frictionless elevated surface at a speed of 8.00 m / s. The block undergoes an elastic collision with stationary block 2, which

31. ## science(chem) plastic hedache...can anyone help?

My hwk Q that I was trying to find the answer to yesterday is this below but I don't know exactly how the placticizing process works. I compiled the chemicals I think I need but other than that I'm stumped as to how to put them together or how. Q: A water

32. ## Dr.Bob => nylon question posted again.since nxt pg

new in bold (copied in normal text) 0.5g hex (1mol/116.21g)= 0.004302mol hex 0.5g adi (1mol/183.03g)= 0.002731mol adi Limiting: 0.002731mol adi(1mol nylon/1mol adi)(226.319g/1mol nylon6.6)= 0.61807 g Nylon Supposed to have theoretically: 0.61807g Nylon

33. ## chemical test

I'm going to do the Baeyer test (Pottasium permanganate) Instructions say to disslove 25mg of unknown or 2 drops of liquid unknown in 2ml of 95% ethanol. Slowly add 1% aqueous solution (weight/volume) of potassium permanganate, drop by drop with shaking,

34. ## science(chem)

How would I make a 5% solution of sodium bisulfite? sodium bisulfite: NaHSO3 Molar mass: 104.06 g/mol is it 5% w/w or v/v or w/v b/c if it was w/w then it would be weight percent w/w= weight solute/ weight solution* 100 I need help on this Thanks

35. ## Science ?

I was making some instant coffee and it had clumped up...I was heating up some water to go and make coffee... Then I just looked in the container and started to shake the container with the lid off a bit..that is when I knoticed the larger clumps of

36. ## Chem drawing

how would I draw this compound? 2-bromo-6-chloro-4,4-dimethylheptane I've tried it again and again but I can't seem to get the Cl on the 6th carbon while still having a 6 carbon chain of heptane I drew it so that it was CH3 CBr CH2 CCH3CH3 CH2 Cl I just

37. ## science(chem)

Concerning TLC plates... 1. why should't I allow the solvent to reach the top of the plate? (I assume it's the same as using paper like I did in gen chem but I'm not sure I know why it shouldn't be allowed to reach the top... what would happen?) 2. why

38. ## Physics

Speedy Sue during is driving at 30.0m/s and enters a 1 lane tunnel. She then observes a slow moving van 155m ahead traveling at 5.0m/s. She applies the brakes but can only accelerate at -2.0m/s^2 b/c road is wet. a) will there be a collision? How do you

39. ## Boiling Point and why one compound boils at higher

which compound has the higher boiling point?? 1) \/o\ 2) \/\OH a)The compound has a larger dipole moment, resulting in more dipole-dipole interactions b)The compound is larger in weight and size and thus has more Van der Waals interactions c)The compound

40. ## science (chem)

Aiieeee! Todays lab...good grief. I was supposed to dissolve 0.3g of impure sulfanilamide in enough ethyl alchohol (95%) and me and my partner did the lab together...sort of. She went and weighed 0.301g of impure sulfanilamide. Then she put some ethanol in

41. ## science(chem)

If these compounds are shaken in a test tube for 10-20 sec will they form a miscible (1 layer) or immisible (form 2 layers)? a) water and ethyl alcohol miscible b)water and dimethyl ether miscible c)water and methylene chloride immisible d)water and hexane

42. ## science(chem)

Indicate the correct waste container for the following compounds choices are halogenated organic, nonhalogenated organic, aqueous, and organic solid a)hexane b)methylene chloride (dichloromethane) c)magnesium sulfate d)10% NaOH e)sodium hypochlorite for

43. ## significant figures

82.453 in 3 significant figures with scientific notation. ~hm..I don't know how to do this...it sounds simple but I'm confused. Help please =)

44. ## science(chem)

CH3CHClCH2Cl vs. CH2ClCHClCH3 How would I know if : -The two formulas represent different compounds which are constitutional isomers. -The two formulas represent different compounds that are not isomeric. -The two formulas represent the same compound. ~if

45. ## Science(chem)

This question relates to what someone posted below... It was explained to them that a reducing agent is oxidized when it reduces? I would like to get this concept straightened out in my head. I originally got this concept when I did gen chem but I have

46. ## Safety of Tooth Bleaching

Just as I promised, here is my reasearch result on bleaching safety. It took me a whole week to compile the information, go to the store, and basically make a report on the topic refering heavily on the British Dental Journal article which was the only

47. ## Dr.Bob - Question

I'm know I'm interested in the chemistry field. The problem is that I have to further narrow down my field of interest. I was curious to know what type of chemistry did you specialize in in the past. -christina

48. ## citation of UNEP PDF online assessment/report

How would I cite a document from the UNEP website? (PDF document) APA style? I've been looking but it looks like you have to cite it a special way? Is this true? I cannot personally find the, "session" or etc. It is a document evaluating the environment,

49. ## science(chem)

I have a question about compounds that oil out of solvents after drying. How would I analyze this? Could I make a KBr pellet, or would I just be able to analyze it in UV spec? I assume that the solvents used to dissolve the compound, would be used as a

50. ## english

I have a general problem with not being able to determine when it is appropriate to use semicolons. I usually use appostrophes and it is incorrect, of course. Is there a way to recognize the place where a semicolon should go? The examples I have seen are

51. ## science(chemistry)

I have a question about TLC plate solvents. What solvents will leave stains on a plate with a TLC plate out of the ones below and why?) (n-Octane, n-Hexane, Decane, Acetone, 1-Propanol, 2-Propanol, Ethanol, Toluene, Cyclohexane, Methanol, n-Heptane,

52. ## science(chemistry)

When performing vacuum filtration of a solid in an unknown solvent, is it necessary to go and find out the solvent composition, so that some fresh solvent can be used to wash the filtrate with?

53. ## science(chemistry)

I have a question about solvent evaporation. If I had an organic layer and an aqueous layer in an unknown mixture of liquids and wanted to obtain the solid of a compound(s) dissolved in the layers, is it reasonable to assume that I can run the compound in

54. ## science(chemistry)

How would I compare using peak heights vs peak areas for GC quantitation? Thanks

Sorry, I didn't see this. Actually you have only one mixture; it happens to have two components. There is a more or less standard procedure for separating complete unknowns (that's where you know nothing about it) and if you know nothing about it that is

56. ## science(chem)

If I have a graph of concentration in Absorbance at 400nm vs [micromolar]of para-nitrophenol The slope would be the extinction coefficient. (y=mx) if forced through 0 The problem is what is y? I know y is the absorbance but it's given on a paper i have as,

57. ## Graphing interpretation

What would it mean if the line of a linear regression graph went through the origin? If it doesn't go through the origin and I make it go through the origin, what am I doing? I was looking for the answer to this and all I came up with was that if the line

58. ## science(chem) Dr.Bob Question from before

The only reason I asked about the balance is that most analytical balances in use in schools weigh to the nearest 0.1 mg although that may have changed since I retired. There are semi-micro balances that weigh to 5 places and micro-balances that weigh to 6

59. ## science(chem)

I'm making different concentrations of ethanol and I just wanted to check my calculations and method. Making ethanol concentrations of: 0.40% 0.30% 0.20% 0.10% 0.05% To make the 0.40% ethanol from stock solution using 100ml volumetric flask: (xg

60. ## science(chem)

The pKa of HEPES is 7.55 at 20C and it's MW is 238.31. Calculate the amounts of HEPES in grams and of 1.0M NaOH in ml that would be needed to make 300ml of 0.2M HEPES buffer at 7.2. I'm not sure how to go about doing this problem. Help please.

61. ## science(chem)

I'm doing an experiment and I'm supposed to have neutral basic and acid samples of solution. I just wanted to make sure that I knew which was which. (If I'm incorrect, please correct me) Acid: 0.7ml 10% H2SO4 + 0.7ml 10% Na2WO4(sodium tungstate) Basic:

62. ## science(chem)

I was wondering how does one make a saturated chemical solution? I'm supposed to make one, is there a way I can determine the ammount solute needed for a certain amount of solvent? If not, how do I make a saturated solution? Thank you

63. ## science(chem)

I need help finding information on how the conway microdiffusion is done/how it works. And why the sample is titrated. Thank you

64. ## science(chem)

I need help finding information on how the conway microdiffusion is done/how it works. And why the sample is titrated. Thank you

65. ## science(chem)

UV I was just wondering how a solvent would affect the spectra of a compound. Like a polar or nonpolar solvent for example: polar: Methylene chloride Nonpolar: cyclohexane, hexane, or ethanol Thanks

66. ## science(chem)

I was just wondering if it was necessary to remember each branch of chemistry learned. I can't really remember general chemistry and I'm sort of loosing the organinc. I mostly remember the calculations and the starting part of each course, but other than

67. ## Law

can someone give me a site that tells me the order of the courts in a state? I don't want to say the state but if needed I will (not sure if each state is different) My teacher isn't clear and thinks that the whole class took law.. divisions civil apella

68. ## Who is correct? (chemistry issues here)

how can this person say that I googled info? (I created it randomly out of my head) and be so ungrateful that I spent the time out of my day to help? Or is it I don't know what I'm talking about and a "condensed structure" is not the answer to the homework

69. ## science(chem)

Commercial hydrazine is sold as a 64% solution. Using that as your starting material, how would you prepare a 5% solution of hydrazine? well if it is sold as 64% solution would that mean that it has 64g of hydrazine per 100ml of solvent(water)? and what

70. ## science(chem)

Commercial hydrazine is sold as a 64% solution. Using that as your starting material, how would you prepare a 5% solution of hydrazine? well if it is sold as 64% solution would that mean that it has 64g of hydrazine per 100ml of solvent(water)? and what

71. ## mistakes?

hm..I was wondering If someone (cough* me) makes mistakes in answering questions, should they bother answering anything at all? Just a thought that crosses my mind alot. =/

72. ## Factoring

(100)d^2-(57.3)d= 0 solve for d. yes...I just can't figure out what number I'd use to factor this and it got bumped to the next page. I thought it was an easy question but... Thanks

73. ## math?? factoring

100N/m d^2 - 57.3d= 0 sigh...I can't figure out how to find d know it's factoring but as to actual number to factor out...not so sure. Thanks

74. ## science(chem)

Can someone tell me if this objective for my lab report sounds alright? The objective of this multistep lab was to ultimately synthesize 4-bromo-2-chloro-6-iodoaniline through the intermediate formation of acetanilide, 4-bromoacetanilide,

75. ## science(chem)

My lab teacher told me to leave my sample mixture of 2-bromobutane and 2-chlorobutane in a solution 1-2ml of sodium bicarbonate. Then I asked after I had wrapped it up, whether there would be a reaction if I left it there for a whole week since that's what

76. ## science(chem)

I have a question about distillation. Or heating in general. When something says heat for 1hr or 1/2 hr do you start counting when you turn on the hotplate? Or do you start counting when the mixture is boiling? I have a feeling that this issue is affecting

77. ## Dr.Bob

I was wondering if I'm synthesizing a product in the end. I shouldn't put the end product of each reaction on the front page as well right?

78. ## chem-> front page report

wondering if this looks good or should I make the format some other way. Multistep Synthesis of 4-Bromo-2-Chloro-6-Iodoaniline name school Chem###sec## Multistep A,B March 13,2008 Multistep C March 20,2008 Multistep D March 27, 2008 Multistep E April 03,

79. ## science(chem)

Ka/Kb for the acetanilide being told that on the basis of this it will tell me whether a nitrogen or oxygen are protonated... (molecule: 4-bromoacetanilide) Thanks

80. ## chem

Br + CHCOOH

book says: (4-4.00x + x^2)(6.00x10^-6C)= x^2(15.0x10^-6C) they got: 3.00x^2+ 8.00x-8= 0 I don't get how they got that quadradic equation. (I mulitplied over and then divided the 15.0x10^-6 over and I didn't get what the book got) (my problem that I'm doing

82. ## Physics-not sure how to find the charge q

Posted by ~christina~ on Sunday, March 30, 2008 at 9:14am. Two small silver spheres with a mass of 10.0g, are separated by 1.00m. Calcuate the fraction of the electrons in one sphere that must be transfered to the other to produce an attractive force of

83. ## Physics..an electric field

4 charged particles are at the cornedrs of a square of side a as shown. a) determine the magnitude and direction of the electric field at the location of charge q b) what is the total electric force exerted on q? basically picture is like this below It's a

84. ## Physics... Coulomb's law

Two small silver spheres with a mass of 10.0g, are separated by 1.00m. Calcuate the fraction of the electrons in one sphere that must be transfered to the other to produce an attractive force of 1.00x10^4 N (about 1 ton) between spheres (number of

85. ## science(chem)

What would cause the peaks in a IR analysis to be smaller than they should be? My sample had the right peaks where they should be and they were the right shape but were shorter then they should be. Something different is what the y axis says on the IR

86. ## from pg 2...Dr.Bob.

Sorry but I have just a few more Q'sfrom what you said And something that I saw today. Actually I was talking about specific course exams. I've been out of touch for awhile so I don't know all the rules about GRE, SAT, GMAT, etc. Do you mean that I ask

87. ## Dr.Bob

I replied to that post from yesterday. I don't know if you saw it.

88. ## Physics (forgot to post this question #2)

During the compression stroke of a certain gasoline engine, the pressure increases from 1.00atm to 20.0atm. If the process is adiabatic and the fuel air mixture behaves a a diatomic ideal gas a) by what factor does the volume change b) by what factor does

89. ## Dr.Bob

welcome back =) and happy easter too.

90. ## K => I answered your question at bottom or next pg

I helped the best I could on your organic chem question

91. ## Physics => waves

It's a simple problem I think but I can't get the answers to match with the book. A particle fingering flute sounds note with frequency of 880Hz at 20 deg celcius(343m/s => sound wave speed) The flute is open at both ends. a) find the air column length b)

92. ## Dr.Bob the question Ihad reposted (NOT the old one

Yes...another calculation problem. Rxn: 1ml isopentyl alcohol + 1.5ml glacial acetic acid + 3 drops sulfuric acid=> isopentyl acetate to calculate the theoretical yield.. I know that the acetic acid is in excess but how would I calculate the theoretical

93. ## Dr.Bob => Can you see the post down the pg by me

I'm trying to post this again..(assuming you didn't see the one below) I posted a question yesterday. I was hoping to catch you before you left on your getaway. =D

94. ## Dr.Bob can you check out the question down the pg

I posted a question yesterday. I was hoping to catch you before you left on your getaway. =D

95. ## Some Lab Question (s)

Yes...another calculation problem. Rxn: 1ml isopentyl alcohol + 1.5ml glacial acetic acid + 3 drops sulfuric acid=> isopentyl acetate to calculate the theoretical yield.. I know that the acetic acid is in excess but how would I calculate the theoretical

96. ## Dr.Bob=> interesting rxn

I was looking at a few videos online. If you type in "top ten amazing chemistry videos" into google and click the first link (wired science), you'll see what I'm speaking of. Well the thing is, I'm curious about the rxn in video # 6. It was described as

97. ## science (chem)

I have a question. I'm forming Isopentyl acetate by the esterfication of acetic acid with isopentyl alcohol. The rxn is shifted so that the ester is produced by using excess acetic acid. In isolating the ester, the excess acetic acid and and isopentyl

98. ## Plastic Moulds ==> Couldn't find anything myself

I'm proposed a way I'd synthesize plastic...polyethylene to shape into a pipe PROBLEM: not sure how or what I would use to make a mold or best method to produce a PIPE not sure what a mold should look like to produce a hollow object like a pipe. OR what

99. ## Physics - drwls can you help me with this?

A 2.00kg block hangs from a rubber cord, being supported so that the cord is not stretched. The unstretched length of the cord is 0.500m and it's mass is 5.00g.The "spring constant" for the cord is 100N/m. Block is released and stops at lowest point. a)