Posts by DrBob222

Total # Posts: 56,062

Chemistry - Equilibrium
You are right and the book is wrong. I played around with the numbers and this what I found. If you don't subtract the 2x from the 6.72E-3 in the denominator AND you don't square the denominator, you gt 8.64E-6. If you subtract the 2x from 6.72E-3 in the denominator ...

Chemistry - Equilibrium
You are right on with everything, BUT the last line; the answer for Kc is not right. I also noticed a typo in the equation but that doesn't affect the work you did.

Science
#3 is the closest although the dictionary defines it a little differently.

Chem
https://socratic.org/questions/how-can-i-draw-the-lewis-structure-for-no

CHEM
This is another LR problem. So go through the math as in the last problem and the grams of product formed is what you get for 100% yield. That is called the theoretical yield (TY). The problem tells you what the actual yield (AY) is. Then % yield = (AY/TY)*100 = ? Post your ...

chem
This step follows to convert mols H2O2 to mols N2. Using the coefficients in the balanced equation, convert mols H2O2 to mols of the product (in this case N2). That is approx 0.26 x (1 mol N2/2 mols H2O2) = approx 0.13 Then do this step to convert mols N2H4 to mols N2. Do the...

chem
2H2O2 + N2H4 --> 4H2O + N2 This is a limiting reagent (LR) problem. You know that when amounts are given for BOTH reactants. mols H2O2 = grams/molar mass = approx 0.26 but that's just an estimate. You should redo ALL of these calculations for all are estimates. mols ...

Science
Inertia is that quality of an object to stay at rest or a body in motion to stay in motion in a straight line unless acted upon by an outside forec. So think about it. If you have a rock rolling down a street, does it make a difference in how much it weighs when you try to ...

Chemistry
Look up kinetic molecular theory on google. What is it you don't understand about gases.

Chemistry
What have you learned about IM forces? https://www.youtube.com/watch?v=a1ZedR-Um84

Chemistry
Use PV = nRT and solve for n = number of mols. Then grams = mols x molar mass = ? Post your work if you get stuck. Remember to use kelvin for T.

Chemistry
mols NaOH = M x L = ? For a monoprotic acid, mols acid = mols base.

AP Chem
C has the LEAST IM forces.

Ap Chemistry
You have three problems here. The secret to each is to recognize that the pH at the equivalence point is determined by the salt present at that point and what that salt does upon hydrolysis. a. HBr + NaOH ==> NaBr + H2O b. HL + NaOH ==> NaL + H2O c. NaHCrO4 + NaOH ==>...

chem
%CO2 = (pCO2/Ptotal) x 100 = ?

chem
Use PV = nRT. Remember T must be in kelvin. Convert to mm remembering that 1 atm = 760 mm Hg.

Science
Here is a table of thermal conductivity. There are several kinds of plstic and several kinds of wood. Take your pick. https://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

Chemistry
rate is (?64/4) with He faster and SO2 slower. There are two correct answers given.

Chemistry
Use PV = nRT and remember T must be in kelvin.

Chemistry - Chemical Equilibrium
Another point you may check is Kp. Is that Kp or Kc. You don't have it in the problem you posted anywhere that I can see. Also, read your problem and check that you copied the number correctly.

Chemistry - Chemical Equilibrium
First off you made a math error. x = 0.08903. Right. But you added that in once and not twice. Total P = 1.124 + 0.08903 + 0.08903 = 1.302 using T as 298. Using T as 298.15 may change that last place but I didn't go through the math.

Math
Isn't it just a substituiion of 12.7 for t and punch the calculator button.

chem
P1V1 = P2V2

Chemistry
Did you mean 50.5%? If so, then 1000 mL x 1.49 g/mL x 0.505 x 1/80.91 = ?M

chemistry
With pH there is a much quicker way of doing this. Ecell = Eo + (0.05916/1)*pH

chemistry
ou can read much more here. https://en.wikipedia.org/wiki/Nernst_equation The reaction is 2H^+ + 2e ==> H2(g) Ecell = Eocell - (RT/nF)log(red/ox) You know Ecell from the problem. Eo is zero. RT/nF is 0.05916/n and n = 2. H2 as a gas and at 1 atm pressure is 1. Solve for H...

Chemistry
I would convert to millimoles. mmols HNO2 = mL x M = about 1200. mmols NaNO2 = about 800. mmols NaOH = about 200. ........HNO2 + NaOH ==> NaNO2 + H2O I.......1200....0........800...... add...........200............... C......-200...-200.......200..... E.......1000...0...

@Kathleen---100th day of school work
You know Google has a calculator built in to your computer. Check it out.

Chemistry
m = mols/kg solution. So a 4.8 m soln is 4.8 mol/kg soln. If you have 4.8 mols in 1 kg how much do you have in 250 g? Wouldn't that just be 4.8 mols x (250 g/1000 g) = ? = say 4.8/4 = 1.2 mols

Chem
mols SA = grams SA/molar mass SA The mols SA = mols ASA since the ratiio is 1:1 in the equatin. Then grams ASA = mols ASA x molar mass ASA SA = salycilic acid ASA = aspirin.

chemistry
2MnO4^- + 5H2O2 + 6H^+ ==>2Mn^2+ + 5O2 + 8H2O Check that equation. mols MnO4^- = M x L = approx 0.0005 but you must redo this to obtain a better answer. Using the coefficients in the balanced equation, convert mols MnO4^- to mols H2O2. That will be approx 0.0005 x (5 mols ...

Chemistry
See the response by Bob Pursley above.

chemistry
There are analytical procedures that you to dtermine the harness of water. You can look most of them up on Google. Na2CO3, sodium carbonate, often is used to "soften" water. One disdvantage is that it adds sodium ions to the water which adds to the daily intake of ...

AP Chemistry
Use the standard reduction tables to find the Eo value of each half reaction. Remember that the Al half rxn is written as an oxidation; therefore, you must change the sign of the Eo reduction you find in the table. Al ==> Al^3+ + 3e Eo = ? Zn^2+ + 2e ==> Zn Eo...

General chemistry
1. t the top of the blue tip or slightly bove. 2. The while "smoke" is part of the MgO escaping. I would quickly move the crucible cover to completely cover the top and move the burner away for 4-5 seconds to allow all of the MgO smoke to be collected and cooled, ...

General Chemistry
These should help. https://socratic.org/questions/how-can-i-calculate-the-empirical-formula-of-magnesium-oxide http://www.webassign.net/userimages/fgdennis@waynecc/Lab_MgO_Intro.pdf

General chemistry
That doesn't tell me anything. But I think what you want to know is the dangers involved with wearing soft contact lenses when working with gaseous NH3. The problem is that the NH3 gas can be trapped between the lens and the eye and if the NH3 isn't flushed immediately...

General chemistry
what experiment?

chemistry
The plastic cup has a little better insulating properties an heat is retained better inside the cup than in a glass cup

Chemistry
What is the N or the acid now? 1.14 g/mL x 1000 ml x 0.20 x 1/49 = ?N Then mL1 x N1 = mL2 x N2 1000 mL x 0.5N = mL2 x ?N2 Subtitute and solve for mL2.

chemistry
Yes, if you set G = 0, that will be the equilibrium point for T and anything less than tht will be OK.

Chemistry
Have you posted all of the problem.

AP Chemistry
OK I don't know what pKa you are using but I obtained 0.0984 for mols base using pKa of 4.20. mol = grams/molar mass. You know mols and you know molar mass, solve for grams. grams = 0.099 x 122 = ?

AP Chemistry
The pH range is pKa for benzoic acid +/- 1 and you will need to look up the pKa for benzoic acid. Where are you having trouble with the problem. You have two ways to go. 1. Start with benzoic acid and add enough NaOH to get the pH you want, or 2. Start with benzoic acid and ...

chem
You can tell from the post that we have little control over the spacing. Not only do we not know what you want but it's almost impossible for us to post that on this site.

Chem
Sarah, do you know how to calculate the amount of NaBr formed (this is a limiting reagent problem). If you do,that calculation gives you the amount of NaBr under 100% yield. % yield = 100(actual yield/1--% yield)

chemistry (need help)
https://www.jiskha.com/display.cgi?id=1518140053

Chem
Is this a monoprotic acid or otherwise? I assume monoprotic. mols NaOH = M x L = ? mols acid = mols NaOH (if acid is monoprotic) mols acid = grams/molar mass. You know grams of the acid and mols of the acid, solve for molar mass.

chem
N2O tell us it consists of 2 mols N and 1 mol O.

Chem
365 x (2Cl/CaCl2) where 2Cl is 2*atomic mass Cl and CaCl2 is molar mass CaCl2.

chem
MgO(s)+H2O(l)->Mg(OH)2(aq) You want 98.9 g Mg(OH)2. How many mols is that? mols = g/molar mass = approx 1.5 but you need to recalculate all of these estimates to get a better figure. Convert mols Mg(OH)2 to mols Mg) using the coefficients in the balanced equation above. ...

plz help right away!!!
1 cm = 4 m. 2 cm = 8 m. 4 cm = ? m.

Chemistry
See if this will help. https://chem.libretexts.org/Textbook_Maps/Physical_and_Theoretical_Chemistry_Textbook_Maps/Map%3A_Physical_Chemistry_(McQuarrie_and_Simon)/03._The_Schrodinger_Equation_and_a_Particle_In_a_Box/3.5%3A_The_Energy_of_a_Particle_in_a_Box_is_Quantized

chemistry
yes.

Chemistry
If you are titrating with the same concn, then v1 = v2 = v3. Reasonably, if it takes a particular volume to remove the 1st H, then it must take twice that much to remove the second and three times that much to remove the third ond.

Math
This forum does not support diagrams/drawings.

Maths
I agree with your interpretation.

@Reiny--Maths
I worried about counting them twice, also; however, I finally decided we had four separate and distinct groups. One pool of 30% had BT, one pool of 25% had MBA, a third pool of 20% had both (this is a separate group that I didn't overlap with the other three), which left a...

Maths
30% + 25% + 20% = 75% hold degrees; therefore, 100%- 75% = 25% that do not x = number of workers 0.25x = 325. Solve for x.

Chemistry
Avery, you need to understand that ammonium is nothing; however, ammonium ION is. As the site Bob Pursley directed you to shows you, ammonium ion (NH4^+) is a weak acid. NH4^+ + HOH ==> NH3 + H3O^+ because NH4^+ donates a H^+ to the H2O.

Maths
Bob Pursley worked this the short way. Here is the long way to do it. P paid C for the bicycle. He sold it for C + 0.1 to Q Q lost 5% when s/he sold it and the selling price was 209 so C+0.1C - (C+_0.1C)*0.05 = $209 1.045C = 209 C = $200 Check it. C paid $200. C sold it to Q ...

Maths
distance = rate x time. d = rt d = 160 = r*4 + 2r*3 Solve for r and 2r. 2r is the speed the last 3 hours. Post your work if you get stuck.

math
I would change the sign by multiplying by -1 and move the 2 to the left side to obtain x^2 -4x +2 = 0 then factor *(it's a perfect square) and solve for x.

Chemistry
k = 0.693/t1/2 Calculate k. Then ln(No/N) = kt No = 8 N = 1 You know k, solve for t. Post your work if you gt stuck.

science
1. Add some water to a 100 mL volumetric flask, add 10 mL of concd H2SO4 DROP BY DROP to the water in the flask, swirling with each drop. If the solution gets too hot let it cool. Add the remainder, then dilute with distilled wter to the mark on the flask. 2. What is your ...

chemistry
REMEMBER that T must be in kelvin.

chemistry
(P1V1/T1) = (P2V2/T2) Post your work if you get stuck.

chemistry
Water vapor, air, dust, pollen, etc, form a mixture which is a solution. As the air cools the solution becomes saturated with respect to H2O and at some point it comes out of solution.

Chemistry
Was it pure? if so, there are 6.02E23 atoms in a molecule; therefore, there are 1.157E20 molecules x (1 mol/5.02E23) = ? mols KMNO4. mols KMnO4 x molar mass = grams KMnO4 = ? Convert to mg.

Organic Chemistry
You ALWAYS lose a little of the solid when recrystallizing anything

Chem Oxidation-Reduction Titrations
I don't think the problem is asking for you to answer by rule number. I think they want you to give the oxidation number. O in H2O2 is -1 for EACH O atom. Cl is +1 NaOCl If those numbers agree with your rules you're oK. For the other part of the problem , remember ...

Science
https://en.wikipedia.org/wiki/Continental_drift

chemistry
Yes, very good.

chemistry
London dispersion forces are present is essentially all molecules but they are only one of several intermolecular forces. Ion-dipole, dipole-dipole, hydrogen bonding, etc are others but they always occur because of some polarity between molecules. For example, both H2O and HF ...

chemistry
yes, very good.

chemistry
1 and 2 can't be right because to have dipole-dipole you MUST HAVE two dipole attracting each other.

Chemistry
E = h*frequency

Chemistry
What is your trouble with this?

Chemistry
I agree with Ray.

Chemistry
Can't you find that on the periodic table?

Chemistry
xxx

Chemistry
I tried to respond but couldn't.

Chemistry
What is your main problem in answering this question?

Chem Oxidation-Reduction Titrations
You didn't answer my question. I know you are titrating bleach and H2O2. What are you titrating it with and what is the concentration of the material with which you are titrating it.

Chem Oxidation-Reduction Titrations
What are you titrating the NaOCl with? H2O2 same question.

Chemistry
You can calculate the H3O%+ if you know Ka for the acid.

AP Chemistry
I've never seen that phrase used in a problem like this where there was no dilution but i assume they want to know the concn of the HCl. There is a formula you can use like this. M1V1 = M2V2 0.5M x 25 mL = M2 x 20 mL and solve for M2. That formula is good only for 1:1 ...

Chemistry
1. There are many definitions of acid and base. If you base the answer on the Arrhenius theory, both provide OH^- in solution. 2. Your anwer for 2 is correct.

Physical Science
q needed = mass H2O x specific heat H2O x (Tfinal-Tinitial). I can't calculate anything because you didn't specify the final T of the water.

chemistry
Water is a polar molecule. If it were a straight line molecule it would not be polar. PPts may or may not sink. It depends upon so many things. density, hydrophyllic or not, particle size and packing, etc. For example, powdered sulfur will float but a chunk of solid sulfur ...

Chemistry
q = mass H2O x specific heat H2O x delta T. That gives you delta H for 14.3 g and the unit is joules. Usually dH is given in kJ/mol. To convert to kJ/mol, convert 14.3 g NaOH to mols. mols NaOH = grams/molar mass = ? Then divide q by mols to get J/mol and convert J/mol to kJ/...

oops--chem
second line and not send line two at the end and not to. These fingers don't work like they did when I was 25 and when I proof my eyes don't work either. :-)

chem
PLEASE write in good style. It is very difficult to read when we don't know whre the sentence starts and where it ends. Also, you might want to proof the posts, too, because this one contains gibberish in the send line. As I interpret this question, actually there are to. ...

CHEM
You are missing something although I didn't give very good directions. #2 is an ether and has the O in the middle. Most ethers are not low on the totem pole as polar compounds. What about the first question?

CHEM
I answered both of these for you. The first one last night and the second one about 10 minutes ago.

Chemistry
Law of multiple proportions, statement that when two elements combine with each other to form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers. The fixed weight is the 1.000 g S. Divide 1.188...

Chemistry
Name the metal first followed by the non-metal "stem" plus "ide". For example chromium oxide in a and zinc chloride in b.

Chem 32
Which one does NOT have an H or an OH on the end?

Science
NOPE

chemistry
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch4/kinetic4.html

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