Monday
October 20, 2014

Posts by DrBob222


Total # Posts: 44,571

Chemistry
Read your problem and your post. I don't believe all of the information is here.
September 3, 2014

Math
To place numbers in increasing order (least to greatest), place the smallest number first followed in succession by the next highest number until the last number is in place.
September 3, 2014

Maths
I would say, "Convert to the same units and compare them".
September 3, 2014

Chemistry
First convert pints to mL. I obtained 62.9 mL but you should confirm that. 196.34 g = mass container + syrup -102.00 g = mass empty container -------------- 94.34 = mass syrup density = mass/volume = ?
September 3, 2014

Chemistry
And the question is ?
September 3, 2014

Chemistry
No it isn't the atomic number; however, I looked up the atomic mass on the periodic table and it is 63.5463 as it occurs in nature. Plug that in for z and solve.
September 3, 2014

Chemistry
I don't think you understand what I need. The ABUNDANCE of 63 is 69.170% and the ABUNDANCE of 65 is 30.83%. But you don't have the mass of anything; i.e., you don't have the mass of 63 or the mass of 65 or the mass of the isotope as it occurs in nature (the mixture...
September 3, 2014

Chemistry
I believe you also need to know the mass of the mixture occurring in nature.
September 3, 2014

Chemistry
I agree with what you have but if your prof is picky about significant figures s/he will tell you that you need another place in your answer. I believe you are allowed four s.f. so I would write that as 0.103928 which I would round to 0.1039 g.
September 3, 2014

Chemistry
let x = fractional abundance of 59Co. and 1-x = fractional abundance of 60Co. ----------------------------------------- x(58.9332) + (1-x)(59.9338) = 58.9901 Solve for x and 1-x to obtain fractional abundances for Co59 and Co60. Then 1.8276 g x fractional abundance Co60 = mass...
September 3, 2014

Analytical CHM
http://academics.wellesley.edu/Chemistry/Chem105manual/Appendices/uncertainty_volumetric.html
September 3, 2014

Analytical Chemistry
Random errors. Errors due to the weights (balance error). Most reading errors have been eliminated due to digital readout. Sloppy handling of sample.
September 3, 2014

Analytical CHM 300
You need to rephrase the question.
September 3, 2014

Sogeri high school
I assume the products are NO2 and H2O N2H4 + 3O2 ==> 2NO2 + 2H2O I will get you started but I'm having trouble understanding why you can't count bond broken and bonds formed. For bonds broken, look at N2H4. There are four N-H bonds broken plus a N-N bond broken to ...
September 3, 2014

Chemistry
q = mass fat x specific heat fat x (Tfinal-Tintial)
September 3, 2014

chemistry
density = mass/volume = 53.9/35.4 = ?
September 3, 2014

Chemistry
I answered this below lat night.
September 3, 2014

Chemistry
% mass C = (2*atomic mass C/molar mass C2H2)*100 =
September 3, 2014

Chemistry
There is a law called the Law of impenetrability which says that two objects can't occupy the same space at the same time. What this means is that the volume of the water in the graduated cylinder will rise an amount equal to the volume of the ice cube; i.e., the ice cube ...
September 3, 2014

Chemistry(Please help)
C is 1s2 2s2 2p1 2p1 and in sp3 hybrids the 1 2s orbital mixes with the 3 2p orbitals to form 4 bonds, all alike, as sp3 hybrids (hybrids as in not an s and not a p but four mixed s & p to form sp3). We write that as 1s2 sp3 sp3 sp3 sp3 with one electron in each of the 4 sp3 ...
September 2, 2014

Chemistry
No you would not do that. Mathmate's directions are to measure out 100 mL and add enough water to it to make a total volume of 600 mL. And to clarify another point, that isn't the same as adding 100 mL of the 36M stuff to 500 mL H2O BECAUSE 100 + 500 may NOT be a final...
September 2, 2014

Chemistry
Note: I am unfamiliar with how the alha amino acids dissociate so look at what follows with a skeptical eye. Here is what I think. With a concn of 0.001 the hydrochloride will consist of the fully protonated amino acid plus the chloride ion. You can assign 0.001 to (Cl^-) ...
September 2, 2014

Chemistry
How many mols CCl4 do you have? That's mols = #molecules/6.02E23 = ? Then there are 4 atoms Cl for each molecule CCl4; therefore, there are 4 x that number atoms Chlorine
September 2, 2014

chemistry
What do think the answer is and why? Oxygen is 1s2 2s2 2p4
September 2, 2014

Chemistry
pi = MRT pi in mm Hg. You know R (0.08206) and T (remember in kelvin). M = mols/L solution. where mols = grams glucose/molar mass glucose and L solution is 0.450 Solve for pi
September 2, 2014

Chem Help Please!!!
Your formulas are right. In general, ionic bonds are formed when elements from the sides of the periodic table (left side and right side) combine. Examples are LiCl, BaCl2, AlCl3 etc. In general, covalent bonds are formed when elements from the center combine with left or ...
September 2, 2014

Chemistry
12Mg is 1s2 2s2 2p6 2s2 20Ca is 1s2 2s2 2p6 3s2 3p6 3d0 4s2 The electrons in the 4s level for Ca are further removed from the nucleus than the outer electrons in the Mg atom and it takes less energy to move them to a higher level. As a result, the energy emitted when the ...
September 2, 2014

chemistry
See your other post.
September 2, 2014

chemistry
mass = volume x density density is given volume = pi*r^2*l r = 1.25/2 = ? pi = 3.14 l = 4.50m = 4500 cm
September 2, 2014

physical science
What's the density of oak? mass = volume x density volume is 12 cc density = ?
September 2, 2014

Science
area = L x W = 15.0 x 14.1 = 211.5 m^2 but the answer is not B. You can have three significant figures (because of the 15.0). I would round that 211.5 to 212 m^2.
September 2, 2014

chemistry
10 grams of what? If you had 10 g CuSO4.5H2O in 100 g H2O then you want get any back. If the 10 g is 10g solution, and the solution is saturated, then you will get 25 g x (10/100) = g CuSO4.5H2O
September 2, 2014

chemistry
Read the label for side effects. Look on the web and HOPE you can find who first manufactured it. You can look for sodium bicarbonate used for acid stomach. Look for aspirin, acetyl salicylic acid
September 2, 2014

chemistry
You asked this same question last night (actually you finished the question last night). Bob Pursely answered the question, you questioned his answer and I followed up with the same answer Damon has given you here. You may as well accept the answer because it's right; both...
September 2, 2014

Chem
26.5 L coolant is 26,500 mL/ mass = volume x density. You know volume in mL and density, solve for grams.
September 2, 2014

Chemistry
Calcium acetate is Ca(C2H3O2)2 which I abbreviate as Ca(Ac)2. Remember the definition. M = mols/L solution. mols given in the problem as 62.1 volume given as 585.1 mL which is 0.5851 L. Then 62.1 mols/0.5851 L = 106.136 M for Ca(Ac)2. There are two Ac^- ions in each molecule ...
September 1, 2014

chemistry
Sr(OH)2 + 2HNO3 ==> Sr(NO3)2 + 2H2O 1. Write and balance the equation as above. 2. How many mols do you have to neutralize? That's mols Sr(OH)2 = M x L = ? 3. Using the coefficients in the balanced equation, convert mols Sr(OH)2 to mols of the other reagent. In this ...
September 1, 2014

Chemistry
Show your work and I'll tell you what is wrong with your factors.
September 1, 2014

Chemistry
How many hours in a week. (24 hrs/day) x (7 days/week) = 168 hrs/week. So (12 donu/36 hrs) x (168 hrs/week) = ? 56 doughnuts/week?
September 1, 2014

chem
Hey, volume is volume. The volume is the same and each will displace a volume of water equal to its own volume, no matter what it's identity.
September 1, 2014

chemistry
SA = salicylic acid ASA = aspirin mols SA = grams/molar mass = ? mols ASA produced = mols SA grams ASA = mols ASA x molar mass ASA. This is the theoretical yield (TY) Actual yield (AY) either 1.15 or 0.15 depending upon how you read the question. % yield = (AY/TY)*100 = ?
September 1, 2014

chemistry
How many moles do you want? That's M x L = ? mols. Then mols = grams/molar mass, You know mols from above and molar mass, solve for grams.
September 1, 2014

Chem Help Please!!! DrBob222
Simple distillation at atmospheric pressure. These differ little from diagram to diagram but the parts are labeled. https://www.google.com/search?q=image+simple+distillation&client=firefox-a&hs=YcY&rls=org.mozilla:en-US:official&channel=sb&tbm=isch&tbo=u&source=univ&sa=X&ei=...
September 1, 2014

chemistry
First, determine the molarity of the solution of HCl and Second, use the dilution formula. 1.20 g/mL x 1000 mL x 0.40 x (1 mol/36.5g) = 13.15 which I would round to 13.2 M Then c1v1 = c2v2 13.2*v1 = 0.2M x 500 mL Solve for v1. You can do the M of the initial HCl solution ...
September 1, 2014

Chemistry
Yes, 1s2 2s1 2p3 would be 2s up, 2p up 2p up 2 up BUT then the four hybridize to form four sp3 hybrid bonds.
September 1, 2014

Chemistry
When bonding in organic molecules in which the C atom shares the four electrons, what happens is that the ground state of 1s2 2s2 2p2 and one of the two 2s2 electrons gets promoted to the 2p and the configuration becomes 1s2 2s1 2p3. Then the 2s1 and 2p3 hybridize to form an ...
September 1, 2014

chemistry
See your other post.
August 31, 2014

chemistry
Are you new to chemistry. Two things to keep in mind. 1. Start sentences with a capital letter and put in periods. Otherwise it makes it difficult to know the question. 2. Find the caps key and use it. Co, CO, and co means something different. 3. Note correct spelling of ...
August 31, 2014

Chemistry
You want to convert rate to time. 7.5m/hr x ?hr = 10,000m Solve for ?hr and convert to minutes. OR, use the distance formula that is distance = rate x time. 10,000 = 7.5 m/hr x ?hr. Solve for ?hr and convert to minutes.
August 31, 2014

chemistry
mass = volume x density or volume = mass/density. mass = 4100 g density 1.11 Substitute and solve for volume (in mL) and convert to L.
August 31, 2014

Algebra
The boat travels downstream at the rate of r+3.5 and r-3.5 upstream. distance down stream = r*time = (r+3.5)*5 and upstream is (r-3.5)*12. Since the distance downstream is the same as distance upstream, these two are equal to each other. (r+3.5)*5 = (r-3.5)*12 Solve for rate ...
August 31, 2014

science
All information that follows is based on FOOD calories (which really are kilocalories). CH2O contains 4 cal/gram protein contains 4 cal/gram fat contains 9 cal/gram so (100*4)+(20*4)+(20*9) = ? %CH2O = [(100*4)/total]*100 = ? same format for protein and fat.
August 31, 2014

science
See your other post.
August 31, 2014

Chemistry
Rf value short wavelength = (distance moved by shortest/distance moved by solvent). Rf value for long wavelength = (distance moved by longest/distance moved by solvent)
August 31, 2014

summer math hw
A1 = pi*5^2 = ? = 25pi A2 = pi*10^2 = ? = 100pi Looks like 4 times.
August 31, 2014

Science(density)
density = mass/volume. You have mass and volume in the problem. Substitute and solve for d.
August 31, 2014

chemistry
Is that millijoules? Multiply by 1E6. Is that megajoules? Divide by 1000.
August 31, 2014

Chemistry
I agree with John.
August 31, 2014

Chemistry
You seem to have the right idea.
August 31, 2014

Chemistry
Your solution assumes that 2-nitrophenol is a strong acid and dissociates completely (100%). But I found a pKa on the web listed as 7.2 which means Ka = 6.3E-8. If we call this compound HP, then ...........HP ==> H^+ + P^- I.......0.0353....0......0 C.........-x......x........
August 31, 2014

chemistry calculations
See your other post below on solving for Kc. This is just a substitution problem. Substitute partial pressures and solve for Kp.
August 30, 2014

chemistry calculations
mols N2O4 = 4/molar mass = 4/92 = about 0.0435M M N2O4 = 0.0435/2 = about 0.0217M ..........N2O4 ==> 2NO2 I.........0.0217.....0 C.........-x........2x E.......0.0217-x....2x Substitute the E line into Kc expression and solve for x and 0.0217-x b and c are done the same way...
August 30, 2014

chemistry calculations
What's your problem here? You substitute the concn listed into the Kc expression and solve for Kc.
August 30, 2014

algebra 2
19.49 x 0.7 = ?
August 30, 2014

algebra 2
550 mi to Texasl 2*550 = 1100 mi for the round trip. 1100 miles x (1 gallon/25 miles) = ? gallons. ?gallons x (1 tank/15 miles) = ? tanks and round to whole number.
August 30, 2014

Chem Help Please!!!
You don't have a manual that gives you this information? Do you have any idea of what you might need? I'll be glad to critique your thoughts.
August 30, 2014

Chemistry
First, balance the equation. C3H8 + 5O2 -> 3CO2 +4H2O. Use the coefficients to convert mols propane to mols O2 this way. 1.75 mols C3H8 x (5 mols O2/1 mol C3H8) = 1.75 x 5/1 = ?
August 30, 2014

chemistry
Convert F to C. That's (F-32)*5/9 = C I came up with 77F = 25C Then C + 273.15 = K I came up with 298.15 K.
August 30, 2014

Algebra 1
let s = side of triangle let q = side of square ----------------- s+4 = 2q (equation 1) perimeters equal so s+s+s+s = q+q+q+q or 4s = 4q (equation 2) Solve the two equations simultaneously for s and q.
August 30, 2014

science
density = mass/volume Substitute and sovle.
August 30, 2014

Chemistry Science
2C8H18 + 25O2 --> 16CO2 + 18H2O 80L gasoline. mass = volume x density = 80,000 mL x 0.703 g/mL = ? mols octane = grams/molar mass octane = ? Using the coefficients in the balanced equation, convert mols octane to mols CO2. Now convert mols CO2 to mass. grams CO2 = mols CO2 ...
August 30, 2014

Physical Science
If the block of wood is homogeneous throughout, yes.
August 30, 2014

chemistry
Lower the temperature. Can you figure from there?
August 30, 2014

chemistry
rate 1 = k(A) = k(1/2) = 1/2 rate rate 2 = k(A)^2 = k(1/2)^2 = 1/4 rate
August 30, 2014

chemistry
71 mass number has abundance of 39.892 let x = mass number of other isotope. % abundance is 100-39.892 = 60.108 Then 71(0.39892) + 0.60108x = 69.723 (from periodic table) 28.32 + 0.60108x = 69.723 x = (69.723-28.32)/0.60108 = 68.9 which I would round to 69 as the probable ...
August 29, 2014

sig figs
I don't obtain that answer at all. 1.277E5 which I would round to 1.3E5
August 29, 2014

Chemistry
What ppt do you want. If you wand PbCl2 then Pb(NO3)2(aq) + 2HCl(aq) --> PbCl2(s) + 2HNO3(aq) Pb^2+(aq) + 2Cl^-(aq) ==> PbCl2(s)
August 29, 2014

chemistry
Follow my directions to get the answer or explain in detail what you don't understand about the directions. Retyping the question won't get it.
August 29, 2014

chemistry
2H2 + O2 ==> 2H2O mols H2 = grams/molar mass Using the coefficients in the balanced equation, convert mols H2 to mols O2. Now convert mols O2 to grams. That's grams mols O2 x molar mass O2.
August 29, 2014

is it correct algebra 2
20 is correct.
August 29, 2014

is it correct algebra 2
I was just showing you how I got the +3. The second term is -[4(-9)/2(6)] The numerator is 4*-9 = -36 and the denominator is 2*6 = 12 so the term is -(-36/12) = -(-3) = +3
August 29, 2014

is it correct algebra 2
When a - sign precedes a set of parentheses, the sign inside is changed. So -(-9-6). Adding inside the parentheses gives -9-6 = -15 and -(-15) = +15
August 29, 2014

is it correct algebra 2
That last term is -(-9-6) = -(-15) = +15
August 29, 2014

is it correct algebra 2
I use parentheses to keep from getting confused and what part goes with what part. (3b)-(4c/2b)-(c-b) but if you used (3b-4c/2b) - (c-b) of course you will get two different answers. [3(6)]-[4(-9)/2(6)]-[(-9-6)] = 18+[(36/12)]+15 = 18+3+15 = 36
August 29, 2014

is it correct algebra 2
- x - = +
August 29, 2014

is it correct algebra 2
2ac-12b 2(-4)(-9)-12(6) -8(-9)-72 72-72 0right ac/b + 2b/a -4(-9)/6 +2(6)/-4 36/6 +12/-4 = 6-3 = 3 =48/2 =3/2 3b-4c/2b-(c-b) 3(6)-4(-9)/2(6)-(-9-6) = 18+(36/12)+15 = 18+3+15 = 36 18-36/12-(-15) 18-36/12+15 -18/27
August 29, 2014

is it correct algebra 2
3ab-2bc a=-4 b=6 c=-9 3(-4)(6)-2(6)(-9) -12(6)-12(-9) -72- -108 = -72+108 = +36 -180
August 29, 2014

Chemistry
molar mass approx 9*12 + 8*1 + 4*16 = 108 +8 + 64 = about 180 mols = grams/molar mass = ?
August 29, 2014

Chemistry
You have 0.1 mol NaCl. That's correct. So there is 1 mol Na/1 mol NaCl and 1 mol Cl/1 mol NaCl. Right?
August 29, 2014

Chem Help
And the lower temperature is important because many compounds decompose at higher temperatures where they might normally boil.
August 28, 2014

Physical sciences
Another one is H2SO4 + NaOH ==> NaHSO4 + H2O Both equations are correct.
August 28, 2014

pmdc
1. mols CO2 = grams/molar mass 2. Using the coefficients in the balanced equation, convert mols CO2 to mols Mg. That will be mols CO2 x (2 mol Mg/1 mol CO2) = mols CO2 x (2/1) = ? 3. Now convert mols Mg to grams. g = mols x atomic mass.
August 28, 2014

Rounding nearest numbers
47,005 rounds to 47,000 to the nearest 1000. 49,904 rounds to 50,000 to the nearest 10,000
August 28, 2014

chemistry
3.7 mg/mL x (1000 ug/mg) x ? mL = 20 ug Solve for ?mL.
August 27, 2014

chemistry
How many mols do you want? That's M x L = 0.35 x 0.500 = 0.175 mols. Then grams = mols x molar mass = 0.175 x 58.44 = approx 10.3 grams NaCl but you need to get a more accurate number. b. There are 0.175 mol and that x 1E6 to give micromoles. c. % what? w/w; w/v; ? I will ...
August 27, 2014

Chemistry
It depends upon how big the fire is and what it is? Almost all labs are equipped with a CO2 fire extinguisher and in general I would use that being careful that the force of the CO2 out of the nozzle did not blow the flames off the bench.
August 27, 2014

Question
http://www.rosamondgiffordzoo.org/assets/uploads/animals/pdf/NakedMoleRat.pdf
August 27, 2014

Haley
If you draw the triangle and label the sides a,b,c and the angles A, B, C, then c^2 = a^2+b^2-2*a*b*cos C I labeled them arbitrarily and worked the cos law three times and came up with angles of 76.4, 57.7 and 45.9 and all of that adds up to 180 degrees.
August 27, 2014

chemistry
mols primary std = g/molar mass = 0.4125/HgO = approximately 0.002 but you need to do that more accurately. Convert mols HgO to mols OH^- = approx 0.004 (again redo all of this). HClO4 + OH^- ==> H2O + ClO4^- 0.004 mols OH will consume 0.004 mol HClO4 M HClO4 = mols HClO4/L...
August 27, 2014

Liz
The answer to a question is 564.90 what? If that is meters, then to the nearest 1 m is 565 and to the nearest 10 is 560 if you are rounding 5s to the nearest even number.
August 27, 2014

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