drbob222

If you rinse with water it dilutes the NaOH that you add later and that isn't what you want.

17 years ago

Are you thinking of stalagmites and stalactites? They are made of CaCO3, calcium carbonate.

17 years ago

See answer above.

17 years ago

I am having a problem understanding your problem. Do you want the orbital notation for all of the electrons, for the valence electrons, for a specific electron, or do you really want the term symbol. For boron, ₅B, the electron configuration is...

17 years ago

One physical change is that the candle melts. One chemical change is that some of the candle (wax--which is a hydrocarbon) combines with oxygen to produce CO2 and H2O. This is an exothermic reaction and produces heat and light in addition to the other pro...

17 years ago

The first equation you have written goes the other direction;i.e., it should be written as 2KOH + H2SO4 ==> 2H2O + K2SO4. The second (ionic equation) is ok and the net equation is ok.

17 years ago

Use PV = nRT and solve for n at the "pocket" conditions. Then PV = nRT again and substitute the surface conditions but use n from the first calculation. Alternatively, you may use P1V1/T1 = P2V2/T2

17 years ago

q1 is ok. q2 is ok. q3 (which you typed in as a second q2) is not correct because you made it a negative number. Since heat is being added it must be a positive number. You should have +889.1 J and the total should have been 3902 J but check my arithmetic...

17 years ago

Usually those things that will solve a problem. Those "things" usually are mechanical devices; in my opinion, ideas are an invention, too, but I don't think the dictionary would support that belief.

17 years ago

If we go by the definition of paramagnetism occurring because of unpaired electrons, then all of the 4f transition metals are paramagnetic except Yb and all of the 5f metals except No. You can look up the electron configuration at webelements com.

17 years ago

At equilibrium the two temperatures are the same; however, in the immediate vicinity, time wise, of pushing the button to react the materials, the T inside is considerably higher than that outside. What methods do you have to measure the temperature of th...

17 years ago

I answered this just a few posts back but the molarity was different. Absorbance = slope x C will get A. Then A = log (1/T) will get transmittance. transmittance x 100 = %T.

17 years ago

Use PV = nRT to calculate mols SF6 in the 8.00 L cylinder and do the same with the 91.0 L cylinder to calculate mols oxygen. Then add to determine total mols of both gases, and use PV = nRT (remember to change T to 78.0 + 273) and determine pressure of th...

17 years ago

Double bonding MAY occur with diatomic molecules but not most of the time. When do we use double bonds. The simplest answer is we use them when the two atoms being bonded must share TWO PAIRS of electrons. Sharing one pair of electrons is a single bond. S...

17 years ago

I slept on this problem over the night and realized early this morning that I didn't answer your question. There isn't anything wrong with what I wrote; I just didn't answer the question. You asked for the PARTIAL pressure of ONE of the gases; I gave you...

17 years ago

Is this the Clausius-Clapeyron equation? Plug and chug.

17 years ago

Do you know that q = mass x specific heat x delta T? And q = mass x heat fusion? What do you not understand about how to use these equations?

17 years ago

You are correct on the micromolar. Note I didn't do the conversion properly. The units don't turn out right, either. 0.002 M x (1 x 10^6 micromoles/1 M) = 2000 micromoles. How do we make the 0.1 M solution? Take 2.42 g of the material, dissolve it in a li...

17 years ago

CCl4 and PCl5 because they are the only symmetrical molecules (and on-ionic) in the list.

17 years ago

Vapor pressure is another way of saying decreasing boiling point. Lower molar masses mean lower boiling points. More hydrogen bonding means higher boiling points.

17 years ago

ryan--Did you post earlier under the name of Matt? I didn't answer that question because a TRIS buffer is made differently. But IF you have a solution of the acid form of TRIS, only (no base present), then 4.80 is the correct answer, I believe. 2. With th...

17 years ago

Look up the electronegativities of the cation and the anion. If the difference is greater than 1.9 or so call it ionic. If less than 1.9 or so call it covalent

17 years ago

go to "webelements dot with the word com" and look up the electronegativity of each of the elements.

17 years ago

Thanks for letting me know.

17 years ago

concn stock solution x 1/100 = ?? concn tock solution x 2/100= ?? concn stock solution x 3/100 = ?? etc.

17 years ago

concn ASA = mols/L 0.4000 g ASA x (1 mol ASA/molar mass ASA) = mols.

17 years ago

Convert 5.45 g SO2 to mols using mols = g/molar mass. Convert mols SO2 to mols H2SO4 using the coefficients in the balanced equation. Convert mol H2SO4 to grams using g = mols x molar mass.

17 years ago

Convert g NaN3 to mols. mols = g/molar mass. Convert mols NaN3 to mols N2 using the coefficients in the balanced equation. Convert mols N2 to grams using g = mols x molar mass.

17 years ago

OK so far but didn't go far enough. The question is for total mols of ions. So you have 0.12 mol/L or 0.06 mols/500 mL. There will be 0.06 mols of Ca^+2, and 2*0.06 mols NO3^- = 0.12 mols NO3^-. The total is 0.06 + 0.12 = 0.18 mol Ca + NO3^-.

17 years ago

Hi Jonny. I didn't understand this question when you posted it yesterday. I still don't understand it. The energy in gasoline originally comes from the energy of the decaying trees, vegetation, etc,from which we get oil and coal, from which gasoline is se...

17 years ago

I posted the above answer. Post your work if you get stuck.

17 years ago

yes. That's the answer I obtaied also. On the others you posted above, I didn't go through any of them in detail. They follow the same general principles. But if you have trouble, post your work and tell us in detail about what you don't understand.

17 years ago

Give me a few minutes to digest this and I'll get back. I don't know exactly when. Let me call you attention to the sentence that starts with, "You also know you have 50 mL ...........moles of total TRIS (in acid or base forms) which ....." <b> That's the...

17 years ago

ok. I now know the answer to my question. The answer is this. When a biochemist says that s/he has prepared a 0.1 M TRIS buffer, s/he means that it is 0.1 M counting BOTH the base AND the acid forms. So it isn't 0.1 M in either although s/he may have star...

17 years ago

I see I made a typo. 50 mL x 0.1 M = 5.0 millimols = 0.005 mols. But 0.005 mols is what I used throughout the remaining part of the problem.

17 years ago

Bob, this is a thought question. You may have thought about this and perhaps you have worked through it but you haven't posted any of your thoughts. I can get you started. Paraffin is a hydrocarbon that is an oil based product. The products of a hydrocarb...

17 years ago

46.0 g gasoline + 173 g oxygen = total mass to start of 219.0 grams. Since CO2 and H2O are the only products formed, their total weight must be 219.0 grams. Law of conservation of mass. Check my arithmetic.

17 years ago

The trivial name for it is soot; however, it is carbon.

17 years ago

I didn't get an answer since the log of a negative number is not possible. The problem would work if it was 100 mL of 0.1 M (instead of the 50 mL). Then we would have B = 0.00334 - 0.002 A = 0.00667 + 0.002 pH = 8.3 + log 0.00134/0.00867 pH = 8.3 + log 0....

17 years ago

Completing the square is a variation, I suppose, of factoring. The idea is to make the number, which isn't factorable (is that a word?) into one that can be factored. For example, X^2 + 4x + 4 can be factored into (x+2)^2. So if we had an equation, such a...

17 years ago

We can't draw graphs on these boards. Sorry 'bout that.

17 years ago

To be perpendicular, one equation must have a slope that is the negative of the reciprocal of the other. The slope of the first one is 6, the second is 1/6, the third is -1/6, the fourth is 1/6.

17 years ago

(36 instructions/microsecond) x (10^6 microseconds/second) x (60 seconds/1 minute) x 4 minutes. Check my work. The units we don't want should cancel and the units we want to keep should stay. Therefore, the final set of units should be instructions for 4...

17 years ago

yes. You doubled the pressure so the volume is halved.

17 years ago

How much buffer do you have? And what is the pH? 50 mL is not enough to still have a buffer after adding the NaOH to a buffer of pH = 7.55. 100 mL of the buffer with a pH = 7.55 would give a pH = 6.94 after adding the NaOH. If you need additional informat...

17 years ago

You are correct that P2O5 is the limiting reagent. You already have the moles P2O5 from your previous calculation. Convert that to moles H2O. Convert moles H2O to grams. Subtract from the original 15.2 to determine the amount H2O remaining. Post your work...

17 years ago

There may be a smaller number but I suggest you convert both fractions to ??/255, then compare them. For example, 13/17 = 195/255.

17 years ago

Molality = #mols/kg solvent mols = g/molar mass mols (NH4)2SO4 = 78.0g x (1 mol/molar mass) = ?? 100.0 g H2O = 0.100 kg. Plug and chug. Post your work if you get stuck.

17 years ago

If one package of candy contains 10 pieces of candy, how many pieces do you have in 5.5 packages. 10 x 5.5 = ?? right? If 1 mol of atoms contains 6.02 x 10^23 atoms, then 5.5 mols of atoms must contain 5.5 x 6.02 x 10^23 atoms. Right?

17 years ago

q = heat absorbed = mass x specific heat water x (Tf - Ti) where mass = 32 grams. You will need to look up the specific heat of water. I think it's about 4 J/g*C. Tf is final temperature. Ti is initial T. Post your work if you get stuck.

17 years ago

Step 1. Write and balance the equation. You have done that except the product on the right should be PbI2. That's just a typo, I know. Step 2. Convert what you have been given ihnto mols. In this case it is M x L = mols. Step 3. Using the coefficients in...

17 years ago

delta T = K_f*molality Plug in 5.00 C for delta T, 1.86 for Kf and calculate molality. Then molality x kg solvent x molar mass = grams. You know molality, kg solvent, and molar mass. Calculate grams. Post your work if you get stuck.

17 years ago

If you don't have an activity series chart in your text or in your notes, you can go to google, type in activity series, and pick and choose from the several that will be shown. I would give you the link BUT I can't post links right now.

17 years ago

<b>Look for the BOLD below</b> Given this information: CxHyOz (s) + O2 (g) ----> CO2 + H20 given: 2.165 g of the unknown hydrocarbon v = 1.868 L P = 130.2 kPa T = 65.0 degrees C g of H2O = 1.818 a)find g H in hydrocarbon 1.18g/18.02 g/mol = .101 mol H20 ....

17 years ago

I worked it through with the new numbers and I think the formula is C3H7O2 but check my work. The ratios seem to work ok with that one change. By the way, I would make a habit of placing the 0 in front of the decimal. It makes it unmistakable that .2 is a...

17 years ago

You want grams, don't you? The formula I have came from this. molality = mols/kg solvent. Solve for mols. mols = molality x kg solvent. mols also = grams/molar mass so we set mols = mols so molality x kg solvent = g/molar mass multiply both sides by molar...

17 years ago

answered above.

17 years ago

That's ethylene glycol

17 years ago

No. I went back and reread the problem. It asks for mols, not grams. so molality = mols/kg solvent and this can be rearranged to molality x kg solvent = mols You know m and you know kg solvent. Solve for mols.

17 years ago

Increasing temperature increases pressure in the cans and they may not be strong enough to withstand the extra pressure. Most cans under pressure also say not to puncture. If punctured, the can releases its contents violently and all at once with the cont...

17 years ago

Water has a high specific heat, one of the highest of all substances. Therefore, it takes a great deal of energy to raise the temperature of a pool of water. Not so for the concrete.

17 years ago

You need to be more specific. I worked problem 3.) for you yesterday and included all the steps, including answers to each step. #2 is worked essentially the say way as is #3. We try very hard to help but help is all we do. You posted three questions and...

17 years ago

We need more information than that. The unit cell of what? Or it may be a generic question but you need to explain to give us a clue as to what you want/

17 years ago

what metal?

17 years ago

C'mon Lauren. We aren't mind readers. Well, some of us may be but I'm not one of the chosen few.:-)

17 years ago

try primitive cubic

17 years ago

same response.

17 years ago

If I interpret the question correctly, there are 4 Na^+ in a unit cell of NaCl and 4 Cl^- in a unit cell of NaCl making, I suppose, 8 for the total number.

17 years ago

Sorry I didn't post my name. My computer shut down, one reason I'm a little late in answering this, and it took a little time to get things back on track. When I first sign on, I get a name of anonymous unless I type in drbob222.

17 years ago

how about celery?

17 years ago

essentially 100%

17 years ago

It "yielded" 8.75 g CrCl3. That means it produced that many grams. What you must do is calculate how much CrCl3 SHOULD have been formed, using 6.37 g Cr2O3 as a starting material. That amount that should have been formed is the theoretical yield.

17 years ago

Not smart. Persistent. I worked the problem and found mass CrCl3 of about 13 grams or so as the theoretical yield. Actual yield of 8.75 g which makes the % yield about 60% give or take a little. Check me out on that. Sometimes I punch the wrong numbers on...

17 years ago

I would GUESS a 4-wheeler might weigh in the neighborhood of 200 or 300 lbs. There must be a variety of weights among the different brands (and there are some 4-wheelers, too). Anyway, convert 200 lbs to grams or kilograms and that get you in the ball par...

17 years ago

The conditions now are likely cold. When the air mass from the Gulf of Mexico hits there will be rain, snow, or freezing rain.

17 years ago

change 3 8/9 to an improper fraction by (9x3)+8 = 35/27 Then 35/9 x 27 = (35x27)/9 = 945/9 = 105

17 years ago

That question was answered by Ms Sue on the question on which you piggy backed the same question. Read the link provided by Ms Sue.

17 years ago

Diversification (multicultural) is one reason.

17 years ago

What about the idea of learning to interact with social skills? That's two out of three. The third one is all yours.

17 years ago

Molecules move rather fast; however, I expect syrup would slow them down somewhat.

17 years ago

And the question is?? And tell us what you don't understand about it.

17 years ago

The diagonal along the face of the crystal for a fcc is 4r. Since you know the radius you can calculate the length of the diagonal. Remember that the diagonal of a right triangle in which the sides are equal is a^2 + a^2 = (diagonal)^2 which allows you to...

17 years ago

volume of 1 unit cell x 6.02 x 10^23 = volume of a mole of unit cells.

17 years ago

answered below.

17 years ago

6.5 g Na2SO4 per 100 g solution. 6.5 goes on top, 100 goes on bottom.

17 years ago

Does it make sense to you that you can subtract 454.935 g from 455 g to make a 6.5% solution? What's X? X is the amount of Na2SO4 that must be added to some water to make the 6.5% solution of Na2SO4.

17 years ago

I don't know that the mass and percent yield has anything to do with the melting point. In fact, I'm pretty sure it has nothing to do with it.

17 years ago

Perhaps your teacher meant something like this. Jan, March, May, July, Aug, Oct, Dec--long months of 31 days. April,June,Sept, Nov--shorter months by 1 day. Feb--shortest month of all. This may not be even close to what you had in mind but months are grou...

17 years ago

No. (X/455) = 0.065 X = 455*0.065 = ?? Grams water = 455 - ?? = xx Then check yourself. (??/455)*100 = 6.5%

17 years ago

Now you tell us!

17 years ago

No. It would be (6.5/100) = (1.50/x g solution) Then cross multiply to obtain, 6.5*x = 100*1.5 x = ??

17 years ago

I would round the 29.575 g Na2SO4 to to 29.6 grams. Remember the question. The question was how to prepare 455 g of a solution that was 6.5% Na2SO4. That answer is to dissolve 29.6 g Na2SO4 in 455-29.6 g water (which would make a total of 455 g).

17 years ago

zeal--strong fervor to do something. Ardor for something. Strong feeling about something. No zeal to live means that person didn't have much incentive to continue living. I have a zeal for making a million dollars but I have no zeal for working that hard.

17 years ago

The digits are right. I would round it to 23 since you have only two significant digits in the 6.5%. But 23 what? grams. mL. ounces. pounds.

17 years ago

molality = m = mols/kg solvent. mols = g/molar mass. You have kg and m so use equation 1 to solve for mols. then go to equation 2, plug in mols and molar mass and solve for grams.

17 years ago

You wrote a small m when you posted the question initially. m = molality not molarity. Look at the definition I wrote above. m = mols/kg solvent. m(of caffeine) = mols caffeine/kg solvent 0.0946 = mols caffeine/0.045 kg CHCl3. mols caffeine = ?? The g caf...

17 years ago

q is usually in calories or Joules (or Kcal or kJ) depending upon Cp. m is usually in grams but it can be in kg or mols, again depending upon Cp. Cp is in J/mol, kJ/mol, J/g, cal/g, or kcal/g. delta T is in C or K. I don't mean to confuse you but I see th...

17 years ago

NaOH + HCl ==> H2O + NaCl What volume of NaOH? L x M = mols What volume of HCl? It had to be the same as the volume of NaOH if both solutions were 1 M exactly. Then L x M = mols. x mols NaOH + x mols HCl MUST form x mols H2O, whatever x is.

17 years ago

Look up anthropophobia

17 years ago

partial pressure and mole fraction

17 years ago