Sheryl

I want to get some equipment to do my own experiments. I'd like to get a stand with a very heavy base. Any recommendations? I believe I will do some titrations using NaOH. I may get a pH meter. Any suggestions welcome. Finals are this week. Thanks for all...

19 years ago

Is there a good article on how to draw resonance structures? Sheryl Sheryl, These are so hard to do on these boards. In fact, I think it is impossible to draw them on these boards. This site may help some. http://web.chem.ucla.edu/~harding/tutorials/reson...

19 years ago

We will be conducting a crystallization experiment this week. I was wondering what the most common materials used for this experiment are and what are their best solvents. Thanks from Sheryl alum in water is really good, however, it takes some time for th...

19 years ago

What is the best solvent for impure fluorene? The possibilities are methyl alcohol, water, and toluene. I'm betting toluene but I don't know its boiling point. Thanks from Sheryl My Merck Index lists 9H-Fluorene as freely soluble in glacial acetic acid an...

19 years ago

Could you tell me what the melting point for a crystallized sulfanamide is? Also, we will have to determine the m.p. of an impure sulfanamide. Any idea of a temperature range for that? Will it be higher of lower? Probably hard to tell since I don't know w...

19 years ago

Benzyl alcohol is not a good sovent with which to crystallize fluorenol. The melting point looks okay so I'm assuming that polarity is the problem. Benzyl alcohol looks polar to me because it has an OH but it is only partly soluble in water. Couldn't find...

19 years ago

The question is: A student performs a crystallization on an impure sample of biphenyl. The sample weighs 0.5g and contains about 5% impurity. Using his knowledge of solubility, he decides to use benzene as a solvent. The final weight is only 0.02g. Why is...

19 years ago

Question: What would happen if a hot saturated solution were filtered by vacuum filtration using a Buchner funnel? Hint: Cooling will occur. My answer: A Buchner funnel is primarily used to collect a solid from a liquid. When the hot solution cools when c...

19 years ago

Question: A compound you have prepared is reported in the literature to have a pale yellow color. When the substance is dissolved in hot solvent to purify it by crystallization, the resulting solution is yellow. Should you use decolorizing charcoal before...

19 years ago

Question: While performing a crystallization, you obtain a light tan solution after dissolving your crude product in hot solvent. A decolorizing step is determined to be unnecessary, and there are no solid impurities present. Should you perform a filtrati...

19 years ago

Question: A student dissolved 0.30 g of a crude product in 10.5mL (the minimum amount required) of ethanol at 25 degrees C. He cooled the solution in an ice-water bath for 15 minutes and obtained beautiful crystals. he filtered the crystals on a Hirsch fu...

19 years ago

Is there a good tutorial on inductive effects, especially as they relate to acids and bases as taught in Organic Chemistry? My book is lacking information on this. The teacher discussed this subject in class today and I think it may have to do with a prev...

19 years ago

A strong acid readily donates a proton. Inductive effects and other factors can stabilize the negative charge of the conjugate base. The more stable the conjugate base, the more acidic the acid. What I don't understand is that it seems to me that a more s...

19 years ago

I won't try to draw one here but take for example, CH3CH2COO-. This has two resonance structures but they look the same to me. The CH2-C single bond can rotate and it looks like you can just flip the COO- section and it looks like the same structure. Mayb...

19 years ago

Problem: In each of the following situations, what type of filtration device would you use? A. Remove powdered decolorizing charcoal from 20mL of solution? My answer: Filter Aid or Celite (diatomaceous earth) B. Collect crystals obtained from crystallizin...

19 years ago

Do you have any idea what the melting points and range might be for a 50/50 mixture of: 1. Benzoin (M.P.: 135-136) and succinimide M.P.: 121-123 and 2. Benzoic acid M.P.: 121-122 and succinimide M.P.: 122-124 I'm doing a lab with really laughable melting...

19 years ago

From part of an earlier question: My question: D. What filtration device would you use to isolate 2.0 g of crystals from about 50 mL of solution after performing a crystallization? My answer was a Buchner funnel Your answer: It would need to be a SMALL Bu...

19 years ago

Question: Two substances, A and B, have the same melting point. how can you determine if they are the same without using any form of spectroscopy? Explain in detail. My answer: Perform a mixture melting point. In this procedure, pulverize and mix A and B...

19 years ago

Question: A compound melting at 134 degrees C was suspected to be either aspirin (mp 135C) or urea (mp 133C) Explain how you could determine whether one of these two suspected compounds was identical to the unknown compound without using any form of spect...

19 years ago

Question: An unknown compound gave a melting point of 230C. When the molten liquid solidified, the melting point was redetermined and found to be 131C. Give a possible explanation for this discrepancy. My answer: The compound sublimed. How would sublimati...

19 years ago

The problem: Write an equation to show how you could recover the parent compounds from their respective salts shown in Figure 12.10. Figure 12.10 is a type of flow chart but I will put it down as best I can. This is an extraction. R-Phenol + RCOOH + RNH2...

19 years ago

My teacher last year in General Chemistry was really great. She was highly organized, always prepared for class, approachable and fair. Chemistry is such a hard class that she really helped me get through it. My Organic teacher is another story. She is a...

19 years ago

How many grams are there in an ounce? Thanks from Sheryl There are 453.592 grams in a pound so divide that by 16 to get 1 oz = 28.3495231 grams How can I teach someone else to read? That's a good question and I'll let the experts give you a complete answe...

19 years ago

a four-component mixture was extracted. In the mixture was R-phenol, RCOOH, RNH2 and R-(C=O)-R in solution with ether and aqueous NaHCO3. RCOO-NA+ was separated out on the water layer. Aq. NaOH was added to the ether layer and R-benzene-O-Na+ was separate...

19 years ago

I'm to describe uses of method. My answer is short. Is it sufficient? Extraction is used to separate one or more components from a mixture. Thanks from Sheryl I think that sounds fine, but I don't know how strict your professor is. :)

19 years ago

Regarding extraction, the heading is: Descripton of method. Principle of operation. My description is: Extraction is based on the principle that a certain solute will dissolve in two immiscible phases, one of which is usually liquid. For example, where on...

19 years ago

We did an extraction. A solid including benzoid acid, p-nitroaniline, and napthalene was dissolved in dichloromethane. HCl was added to give the aqueous salt of p-nitroanaline. NaOH was added to give the aqueous salt of benzoic acid. Napthalene remained....

19 years ago

Extraction procedure and equations: Thought I'd better post this on the current page. I need the reaction equations checked. I tried to put them in bold but can't. They should all be after Reaction: Solid benzoic acid, p-nitroaniline and napthalene -> Dis...

19 years ago

Does anyone know what kindo of chemistry lab course(Organic, Physical, etc.) might use a soxhlet extractor in the experiments? Sheryl http://en.wikipedia.org/wiki/Soxhlet_extractor Certainly Organic It is used in organic chemistry. The URL provided by Lan...

19 years ago

We're doing a TLC analysis of analgesic drugs. One of my prelab questions is: Name some advantages of using acetaminphen (Tylenol) instead of aspirin as an analgesic. They were probably dissolved in methylene chloride amd ethanol and I'm assuming that's b...

19 years ago

Question: A student spots an unknown sample on a TLC plate and develops it in dichloromethane solvent. Only one spot, for which the Rf value is 0.95, is observed. Does this indicate that the unknown material is a pure compound? What can be done to verify...

19 years ago

Question: You and another student were each given an unknown compound. Both samples contained colorless material. You each used the same brand of commercially prepared TLC plate and developed the plates using the same solvent. Each of you obtained a singl...

19 years ago

Question: Each of the solvents given should effectively separate one of following mixtures by TLC. Match the appropriate solvent with the mixture that you would expect to separate well with that solvent. Select your solvent from the following: hexane, met...

19 years ago

Question: Consider a sample that is a mixture composed of biphenyl, benzoic acid and benzyl alcohol. The sample is spotted on a TLC plate and developed in a dichloromethane-cyclobutane solvent mixture. Predict the relative Rf values for the three componen...

19 years ago

Question: Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. A. A two-component mixture containing 1-octene and 1,4-dimethylbenzene gave only one spot with an Rf value of 0.95. The solvent...

19 years ago

What is the difference between these two questions? They look the same to me, like they're asking the same thing. Not likely. Question: A student spots an unknown sample on a TLC plate and develops it in dichloromethane solvent. Only one spot, for which t...

19 years ago

Question: When a TLC plate ws developed, the solvent front ran off the top of the plate. What should be done to correct the error. Me: The only reason I'm giving you this question to check is that it seems too simple. My answer would be to stop developmen...

19 years ago

Question: A student spots an unknown sample on a TLC plate and develops it in pentane solvent. Only one spot, for which the Rf value is 0.05, is observed. Is the unknown a pure compound? What can be done to verify the purity of the sample using TLC? My an...

19 years ago

Sugar oxidizes pretty easily, doesn't it? And ketone not as well? Thank you. Sheryl I think that is right. Alcohols go to aldehydes and they go to ketones.

19 years ago

Question: A colorless unknown substance is spotted on a TLC plate and developed in the correct solvent. The spots do not appear when visualization with a UV lamp or iodine vapors is attempted. What could you do to visualize the spots if the compound is th...

19 years ago

What is the electronic configuration of carbide C-4? Thought it was 1s2 2s2 sp2. Thanks from Sheryl C is atomic number 6. Electronic configuration of the neutral atom is 1s2, 2s2, 2p2. The carbide ion, C^-4, has four more electrons. So the extra four elec...

18 years ago

What is the product of: CH3COCH3 + Na+NH2- ? Thanks from Sheryl I can't help with this one. Sorry.

18 years ago

I've done some TLC plates using ethyl acetate with 0.5% glacial acetic acid as a solvent. The structure of these substances looks polar to me. I"m assuming that ethyl acetate is not very polar. Is this correct? Acetaminophen barely travelled any distance...

18 years ago

Is coordination the same as ionic bonding? Sheryl As I understand coordination, as in coordination number, no. It is more covalent or more precisely called coordinate covalent if we are talking abouat the same thing. Then I guess 'salt formation' would be...

18 years ago

Question: Interactions: Summarize this section (in the book) in your own words and for each interaction give a complete sentence. The strength of interactions of eluted compounds with alumina or silica gel depends on how strongly they are adsorbed to the...

18 years ago

We did a column chromatography then a TLC on extracted spinach pigments. Question: Why are the chlorophylls less mobile on column chromatography and why do they have lower Rf values than the carotenes? My answer: The chlorophylls are more polar than the c...

18 years ago

Question: What would happen to the Rf values of the pigments if you were to increase the relative concntration of acetone in the developing solvent? Note: The development solvent used was 70% hexane - 30% acetone. My answer: Acetone is more polar than hex...

18 years ago

The question asked is: Using yur results as a guide, comment on the purity of the material in the green and yellow bands. (from a TLC of spinach extraction pigments.) I'm not quite sure what they want here and my plate is in the lab, not here. There were...

18 years ago

Question: A sample was placed on a chromatography column. Methylene chloride was used as the eluting solvent. All of the components eluted off the column, but no separation was observed. What must have been happening during this experiment? How would you...

18 years ago

Question: You are about to purify an impure sample of naphthalene by column chromatography. What solvent should you use to elute the sample? My answer: Naphthalene is very nonpolar so a very nonpolar solvent like hexane should be used.

18 years ago

I did a column chromatography on spinach and then a TLC. On the TLC I got five visible bands of colors. On the extracted yellow substance I got one yellow band (carotene) and on the green I also got only one green band. I thought there would be more bands...

18 years ago

I'm trying to figure out some incorrect answers on my last test. I'll try to explain what the original structure looks like and hope you can decipher it. It is a cyclohexane with two double bonds. Carbon # 1 has a double bond to its left and none to its r...

18 years ago

Is there a good tutorial that you know of on Fisher projections? My book isn't helpful. Thanks from Sheryl http://www.bluffton.edu/~bergerd/Models/chiral6.html I don't have the right plug-in for this lesson and I can't find it. Is there another tutorial t...

18 years ago

I'm having trouble understanding what an azeotrope is. Any clarification is appreciated. Sheryl Two liquids with different boiling points normally can be separated by fractional distillation; i.e., the lower boiling point material boils first and when all...

18 years ago

Why does the boiling point of a two-component mixture rise slowly throughout a simple distillation when the boiling point differences are not that large? Thanks from Sheryl

18 years ago

Question: A solid substance has a vapor pressure of 800 mm Hg at its melting point (80 degrees C). Describe how the solid behaves as temperature is raised from room temperature to 80 C while the atmospheric pressure is held constant at 760 mm Hg. I think...

18 years ago

Is there a good tutorial on how to read phase diagrams? Thanks from Sheryl I don't know how good this site is but it has a discussion as well as some questions (with hints) at the end. http://www.science.uwaterloo.ca/~cchieh/cact/c123/phasesdgm.html

18 years ago

Question: A substance has a vapor pressure of 50 mmHg at the melting point (100C). Describe how you would experimentally sublime that substance. My answer: I would put the substance in a sidearm test tube apparatus, put ice in the smaller tube and apply p...

18 years ago

I isolated eugenol from cloves in the lab using extraction and steam distillation but we did not do infrared. The lab report question is: Description of Method. I'm not sure what to put. We prepared the spice, did steam distillation, extracted the essenti...

18 years ago

Question: A mixture of p-nitrophenol and o-nitrophenol can be separated by steam distillation. The o-nitrophenol is steam volatile, and the para iosmer is not volatile. Explain. Base your answer on the ability of the isomers to form hydrogen bonds interna...

18 years ago

Do industrial or other labs often use plastic joint clips to hold distillation flasks and condensers together or do they do as is done in my college lab which is using three clamps - one for the distillation flask, one for the condenser, and one for the r...

18 years ago

If you knew that you had either cyclohexane or cyclohexene in the lab but weren't sure which, how could you determine which it was? Thanks from Sheryl Since I'm not an organic chemist I would think of an organic test LAST. Density, refractive index, and b...

18 years ago

I don't understand how to get a rate determining step. I have an energy diagram for a two-step conversion where the first step Ea is about 18 units. The energy then goes down about 4 units and rises again about 10 units to the peak of the second step. Why...

18 years ago

Is it possible to attach a picture to my question? I've run across a picture of a piece of chemistry equipment and I'd like to know what it is. Sheryl

18 years ago

This is a practical question. I'm working on some raised bed gardens that are very overgrown with tree roots. I've been told to line the outside of the boxes about 2' down with siding and since tree roots are mostly near the surface, that should stop them...

17 years ago

I'm going to buy a Bunsen burner to be used with a propane tank. Is it very important to get a propane burner or does the natural gas one do the same thing? Any advice on what type of burner to get? I'll be working on distilling alcohol and steam distilla...

17 years ago

I did a lab where I had to decompose the compund patassium cholorate (KClO3)by heating,I had to weight the test tube then the test tube with the potassium chlorate to get the weight. I then had to heat it for several minutes and letting it cool down befor...

16 years ago

I'm interested in teaching myself Precalculus and would like to find a good book with lesson plans and assignments. Any ideas?

15 years ago

An audit trail allows an individual to track a transaction from the journal entry to the general ledger through to the financial statements. The audit trail can also find all the transactions that comprise the dollar amount for each account listed on the...

15 years ago

How do you factor this completely: x^3 + ax + 3a + 3x^2

15 years ago

For the year ending December 31, 2010, Johnson Manufacturing Company had depreciation totaling $38,000 on its office equipment. Give the journal entry to record the adjusting entry.

15 years ago

Which has a larger radius, the oxygen atom (O) or oxygen ion (O-2) ? Explain. Isn't the ion bigger because negative ions are bigger than atom's radius. im not sure though.

14 years ago

a partial balance sheet and income statement for King Corproation follow: KING CORPORATION Partial Balance Sheet December 31,2009 Assets Current assets: Cash $33,493 Marketable securities $215,147 Trade receivables, less allowance of $6,000 $255,000 Inven...

14 years ago

The following financial data were taken from the annual financial statements of Smith corporation: 2007 2008 2009 Current assets $450,000 $400,000 $500,000 Current liabilities $390,000 $300,000 $340,000 Sales $1,450,000 $1,500,000 $1,400,000 Cost of goods...

14 years ago

Skewed distributions were discussed in this week’s readings. Think about some of the psychological studies you are familiar with and the constructs investigated in those studies. Describe the study you are referring to and give some examples of the variab...

14 years ago

I do NOT get this, please help: (11x^2+2x^3+14+17x)/(2x+5)

14 years ago

1. A rectangle has an area of x3 + x2 – 7x + 2 square meters and a width of x – 2 meters. Find its length.

14 years ago

2/3x+4 + 6/x+2

14 years ago

Two tugboats are towing a ship. each exerts a horizontal force of 5 tons and the angle between their tow ropes is 90. what net force is exerted on the ship?

14 years ago

The brakes of a care are applied to give it an acceleration of -3m/s^2. The car comes to a stop in 5 s. What was its speed when the brakes were applied?

14 years ago

Solve both equations for v. Kinematic: v=v0+at Energy: 1/2mv^2=mgh I have the height and time: Hgt: 2ft Time in second: 0.3 How do I find Velocity(v) in m/s(kinematic) and Velocity(v) in ft/s (energy)? I'm not sure where to start.

14 years ago

Read text below. Label 5 sentences with feedback (complete sentences), using these five types of feedback: Evaluative, Interpretive, Supportive, Probing, Understanding. The fear of using computers stems from several reasons. Most people don’t understand e...

14 years ago

I have to give the following feedback to this paragraph: (Evaluative, Interpretive, Supportive, Probing and Understanding). I don't know how to start or if I have to use all the 5 types of feedback. This is the paragraph I have to read and give feedback o...

14 years ago

What fuel other than uranium can be used in a nuclear reactor? Is the answer: Neptunium and plutonium, which are transuranium elements.

14 years ago

Why can neutrinos travel immense distances through matter whereas other elementary particles cannot?

14 years ago

How does the number of neutrons in a stable nucleus compare with the number of protons? Why is this?

14 years ago

Find the Kinetic energy (in keV) of 12 6 C atom of mass 12.0 u whose speed is 2 x 10^6 m/s.

14 years ago

The binding energy of 20 10 Ne is 161 MeV. Find its atomic mass.

14 years ago

An electron microscope has a much greater useful magnification than an optical microscope because it can resolve smaller details. What makes the higher resolving power possible?

14 years ago

Why is the Bohr Theory incompatible with the uncertainty principle?

14 years ago

Why do you think the wave aspect of light was discovered earlier than its particle aspect?

14 years ago

The local hardware store and a master gardener suggested the siding solution but it sounds like that is even temporary. No one liked the landscape fabric as a solution because it won't stop roots. Thanks for the input. Sheryl

17 years ago

I have lyme disease and antibiotics are of limited use for many of us. My M.D. is prescribing herbs (as are the doctors in many cases at the lyme clinic) which are very expensive. I want to try to brew up my own, especially tinctures, and will probably en...

17 years ago

I am not really sure at this point that's why i could use some help, I am having serious writer's block!! I am not trying to cheat I just need some help to get me started on this!!

14 years ago

As we move to EHR era, we will have quick access to health care which can facilitate faster health care delivery and treatment. Also, patients can take an active role in their health because they will have the access to their medical records when needed a...

14 years ago

Is this good feedback for this paragraph? Evaluative: I think this is a good start but not enough supportive information. Supportive feedback: I found that this paragraph did not give enough support to why there was a fear of using computers, why people w...

14 years ago

The instructions are: From the piece of writing which follows, write at lest one complete sentence of feedback in each of the five types described in this section: Evaluative, Interpretive, Supportive, Probing, and Understanding. Label each of your five s...

14 years ago

Evaluative: The fear of using computers stems from several reasons. Interpretive: Supportive: lack of understanding will create tension and ultimately lead to fear. Probing: Understanding: Fear of computers is primarily fear of the unknown.

14 years ago

Evaluative and Interpretive: The writer has a good start. However, I feel there could have been more information supporting why people don't understand computers and why they are fearful of learning new technology.

14 years ago

Thank you for helping me better understand this assignment. I just wanted to know if I was on the right track with what I already wrote. I understand that I have to write one for each category.

14 years ago

Thank you, Thank you, Thank you. I just needed to know I was going in the right direction.

14 years ago

my computer got hung up and i clicked submit by accident more than once by accident.

14 years ago

This is the part that will calculate the total number of license plates possible. def main(): num_of_poss_plates = 5*26*10*10*10 print('The number of possible plates are: ', num_of_poss_plates) main()

12 years ago

Go to Google and type in The Sport of Kings: Polo. I think you will get the answer you are looking for. There is an excellent article done by CBS News.

12 years ago

3/4 divided by 7/12 is the same as 3/4 X 12/7. This is the same as (3X12)/(4X7) which can first be reduced down to (3X3)/(1X7)= 9/7 or 1 and 2/7.

12 years ago

The easiest way to do this is do (30X 3) + (4X3) or 90 + 12 which is 102. No regrouping needed. This is called Partial products method.

12 years ago

Place value is what the position of a particular numeral represents. For instance, in 43, the 4 represents 40 since it is in the 10's place value column and the 3 represents 3 since it is in the Ones Place value. 40 +3 = 43.

12 years ago

Seet up a proportion of Shadow/height for each object. So Shalonda would be 8/4 and the flagpole would be 28/x. so 8/4 = 28/x. Cross multiply and divide. (28 X 4) / (8x) or 112/8 = x. So the pole is 14 feet tall which makes sense if her shadow is twice as...

12 years ago

If radius and height are halved, then the total surface area is 1/4 the size. (1/2)^2 = 1/4. So 218 /4 = 54.5 units squared. We get the relationship from SA being 2 dimensions, so we square the ratio. If this were volume, you would cube the scale factor r...

12 years ago

Assuming the dice are 6 sided, there are 36 possible outcomes to this situation, 6X6. How many are multiples of 7? Check the sample space, none of them are multiples of 7,impossible to get without a 7 involved.

12 years ago

Make a list of factors for both the coefficient of the x^2 term and the constant. In this case, 1 and 10. so 1X1 and then 1X10 and 2X5. Also, the fact that the constant is a negative 10, that means one of the 2 binomials must be negative. Then you look fo...

12 years ago

"How much more" would be subtraction, so subtract the smaller from the larger. 2/3 -5/9. (You can tell 2/3 is larger because the closer the numerator is to the denominator, the larger the fraction) Get common denominators or "names" as I like to use so th...

12 years ago

1/3 is your new whole, NOT 1. So take 1/4 of 1/3 + 1/6 of 1/3 + 1/6 of 1/3. Pretend there are 180 plants. That would make 60 of them on sale. 1/4 of that is 15, 1/6 is 10 and 1/6 is 10. so that makes 35 out of the 180 is 7/36. 1/12 +1/18+1/18 or 3/36 + 2/...

12 years ago

You cube the scale factor, so 4^3 = 64 times. lwh = 4lX4wX4h = 64lwh.

12 years ago

Wolframalpha is a great site for these type of problems. Check it out.

12 years ago

pythagorean theorem.....if the height is 4 times, and it must reach 16, then the distance along the horizontal must be 4. so 4^2 + 16^2 = c^2. where c is the length of the ladder. Use a calculator to solve.

12 years ago

You have to factor the polynomial. If for instance you get (x-3)(x+2), then your x intercepts are where you take each to equal 0. (x-3)= 0 so x = 3; and (x+2) = 0 so x = -2. The x intercepts are the opposite sign of the values of the constants in each bin...

12 years ago

8 - 12

12 years ago

2:3

8 years ago

Thank You!

4 years ago

Please give me the solution to it

4 years ago