Posts by DrBob222

Total # Posts: 55,559

@ Rae
I disagree. One person that needs to know is the the cheater; others who MAY cheat also need to know.

CHEMISTRY
4.5% of what strength HNO2? What's Ka of HNO2?

CHEMISTRY
See your duplicate post above. Please use the same screen name.

Chemistry
2 mols C2H6 = 7 mols O2 = 4 mols CO2 etc.

Chemistry
No. v doesn't matter.

Chemistry
If you are determining the number of nodes, and the p orbitals are degenerate, no. However, if the p orbitals are not degenerate then you will have three orbitals but pointed in three directions (along the three axes). YOu can read all about it here. https://en.wikibooks.org/...

Chemistry
(V1/T1) = (V2/T2) Remember T must be in kelvin. ?

chemistry
q = mass H2O x 44.0 kJ/mol = ? Remember to convert the H2O to mols. mols = grams/molar mass = ?

Check my answers Ms. Sue
I disagree with C.

Chemistry
This is a problem to illustrate the common ion effect. The common ion, in this case, is F^- from KF and the presence of KF will decrease the solubility of LfF3 in water. ........LaF3 ==> La^3+ + 3F^- I.......solid.....0.......0 C.......solid.....x.......3x E.......solid...

Chemistry
P*molar mass = density*RT Substitute and solve for molar mass. Remember P = 80.2/760 and T = (273+23)K Then density at STP is molar mass/22.4 = ? g/L.

chem
First we must determine the limiting reagent(LR). mols F2 = approx 70/38 = about 1.84. 2.0 mols CF2Cl2 will produce 2 mols CF4. 1.84 mols F2 will produce 1.84 mols CF4, Therefore, the LR is F2 and CF2Cl2 is in excess. So the rxn releases 401 kJ for 38 g F2. You have 70 g; ...

Science
Read the first paragraph on this page.The key word is nucleus. https://www.google.com/search?q=prokaryotic+vs+eukaryotic&ie=utf-8&oe=utf-8

Chemistry
How many mols do you want? That's mols sucrose = M x L = ? Then mols = grams/molar mass. You know molar mass and mols, solve for grams.

Chemistry
The mass of 1 mole of anything is the same as the molar mass in grams; therefore, mols = grams/molar mass = ?

Gen chem
H2SO4 + 2NaOH ==> 2H2O + Na2SO4 moles NaOH = M x L = ? Using the coefficients in the balanced equation, convert mols NaOH to mols H2SO4. Then M H2SO4 = mols H2SO4/L H2SO4. You know M and mols, solve for L and convert to mL.

Chemistry
I agree citric acid is the LR but I worked it another way. You can compare mols and not go through the grams step.

Chemistry
Yes. This is a standard question in qualitative analysis but it's a little confusing; i.e., I don't know if the idea is to identify the solutions, add an ion which will form a ppt in BOTH, or just what. You need to know the solubility rules. Chloride ion (say NaCl) ...

Chemistry
I didn't get 32 but almost twice that. Post your work and I'll look for the math error.

Chemistry
q = mass H2O x specific heat water x (Tfinal-Tintial) sp.h. stands for specific heat and qcal is calorimeter constant. mass warm H2O x sp.h.H2O x (Tfinal-Tinitial) + mass cool H2O x (Tfinal-Tinitial) + qcal(Tfinal-Tinitial) and solve for qcal. Post your work if you get stuck. _

Chemistry
Some of these look like relatively easy questions to answer so I don't understand what you could be troubling you. If you will explain in detail what you don't understand about each I'll show you what to do.

Science
KE = 1/2*m*v^2

Science
I agree

Chemistry
Remember to ignore that 55.0 g NH4HS since it is a solid and doesn't enter into Kc (or Kp). For every mole of NH4HS that decomposes there will be x mols NH3 and x mols H2S. ......NH4HS --> NH3 + H2S I.......solid....0.....0 C........-x......x.....x E......solid-x...x...

Chem 1C
Can't you use the Arrhenius equation, just plug in the numbers and turn the crank.

Gen chem
H2SO4 + 2NaOH ==> Na2SO4 + 2H2o mols NaOH = M x L = ? Using the coefficients in the balanced equation, convert mols NaOH to mols H2SO4. Then mols H2SO4 = M x L. You know M and mols, solve for L and convert to mL. Post your work if you get stuck.

Chem
To save time I will omit the aq part but you can add that to each cation and anion yourself. I have added (s) to the AgCl to show it is solid. Ag^+ NO3^- + Na^+ + Cl^- ==> Na^+ + NO3^- + AgCl(s) Cancel the ions on each side that are common to both sides to end up with the ...

Chemistry
mols Fe(NH4)2(SO4)2.6H2O = grams/molar mass = ?. Then (A) = mols /L = ? Let's call this Y. (B) = (A) x (5.00/100) = ? (C) = done the same way as (B).

Chemistry
See your other post.

Chemistry
By the way, please don't change screen names. You get faster service using the same name.

Chemistry
See your other posts.

chemistry
Technically, I don't think this is a viable problem because it gives a SOLUTION of Al while the rxn is Al solid. mols Al = M x L = approx 1.7 but you need to do this more accurately. Then -3339.6 kJ/4 mol Al x 1.7 mol Al = approx ?

chemistry
See the post above by anonymous.

Chemistry
The net ionic equation is H^+ + OH^- ==> H2O K^+ and Bar^- are common to both sides and cancel.

Chemistry
1.0929 g/mL x ?mL x 0.19 = 30.0 Solve for ?mL.

Chemistry
yes, both b and c are wrong. I suspect you just didn't read the other digits on your calculator.

@Bosnian
Note that your solution doesn't give the right units. 1/23 is 1 mile/23 gallons or 0.0435 miles/gallon. You want ? gallons/mile which is 23/1 or 23 miles/gallon.

@ Kim
I don't buy 31.02 g. The correct answer is approx 62 g NH3 or 92.2 kJ will produce 34 g NH3 so 168 will produce 34 x 168/92.2 = ? OR, in your work you show 1.82 and that 1.82 x 2*17.03 is correct because there is a coefficient of 2 for NH3 in the reaction.

chemistry
6 g H2 releases 92.2 kJ so 92.2 x 13.3/6 = ? kJ.

Chemistry
q is - since T is higher (exothermic). w is - since work is done ON the system.

chemistry grade 12
Are you sure air contains 78% H2O at 25 C?

Slit width in double slit experiment
I can answer that last question for you. The tutors here are allowed to post links by the web master. Only the tutors who have been cleared can do that.

Chemistry
Going to the front of the class means going to the head of the class which means you have done a very very good job and you're at the top of the class. It's a very high compliment. 2AgNO3 + CaCl2 ==> 2AgCl + Ca(NO3)2 mols AgCl obtained = grams AgCl/molar mass AgCl...

Chem
Yes.

Chem
yes. Go to the front of the class.Very good.

Chem
See my response above.

Physical chemistry
mols H2, use PV = nRT and calculate n. mols I2 do the same and find n. Then initial (H2) = n/L and initial (I2) = n/L Do you have a pressure? or some other way to calculate n? ....H2 + I2 ==> 2HI

Physical chemistry
initial (H2) = 0.1mol/1 L = 0.1M initial (I2) = 0.lmol/1 L = 0.1M ......H2 + I2 ==> 2HI I....0.1...0.1.....0 C....-x....-x......2x E...0.1-x..0.1-x...2x So you know I2 at equilibrium is 0.02M which means 0.1-x = 0.02. At equilibrium H2 must be the same. Calculate 2x = (HI...

CHEM
mols KCl = grams/molar mass = approx 0.5 but that's just a close guess. mols CaCl2 added = M x L = approx 0.03 or 0.03 mols Ca^2+ and 0.06 mols Cl^-. Total K = 0.5 and total volume = 0.07L, then M K^+ = mols/L = ? total Cl = 0.5 + 0.06 = 0.56 and total volume is 60+10 = 70...

Chemistry
This is an example of a "work horse" problem designed to make you think through many steps. Do what you can, show your work, and someone will help you finish if you explain what you don't understand about the next step.

chemistry
Yes. H2SO4 is sulfuric acid. H2SeO4 is selenic acid.

Chemistry
h is in units of J*s and not J/s. Scroll down to "value" in this url. https://en.wikipedia.org/wiki/Planck_constant

Chemistry
The 2 is n in the work I provided; i.e., dGorxn = (1*dGo products) - (2*dGo reactants. And yes, I don't know how to write a delta sign so dGo means delta Go. The capital D refers D glucose and capital L to L lactose.

Chemistry
Yes, but first you must find dGo for the reaction. That is dGorxn = (n*dGo products) - (n*dGo reactants). Remember to use 8.314 for R.

Chemistry
You want a book? How many mols do you need? That's moldm-3 x dm^3 = ? Then mol = g/molar mass. YOu know molar mass and mols, solve for grams, add that amount to a 500 cm3 volumetric flask, dissolve, mix thoroughly, stopper. I don't think you have named sodium carbonate...

Chem
mols NaBr = grams/molar mass = ? Then M = mols/L

Chemistry
m = mols H2SO4/kg solvent. mols = grams/molar mass = ?. Substitute and calculate m. M =mols/L for mols: mols H2SO4 from above for volume: volume in mL = mass/density and mass solution = 100 g. Solve for volume, convert to L, substitute and solve for M. Post your work if you ...

Chemistry
But that is if the liquid is at the boiling point of ethanol. If the ethanol is t a temperature lower than the boiling point then more energy is required for every degree < the b.p.

Chemistry
Pretty general and with no context; however, this may fit. it requires 200 calories of energy to change the phase of 1 gram of ethanol at its boiling point from liquid to vapor.

Chemistry
1. Who knows? You must know the mols HCl and mols CaCO3 before you can answer this question. 2. What is part B? 3. Strong base and weak acid, I would use phenolphthalein.

Chemistry
Without knowing what you are doing or anything about your experiment, I'm no help.

organic chemistry -urgent
Tutors here are not clairvoyant. I have no idea what you are doing other than that it is a chromatography experiment

organic chemistry -urgent
See your post above.

CHE102
1. You have the balanced equation. 2. Convert g Al to mols. mols = grams/atomic mass. 3. Using the coefficients in the balanced equation, convert mols Al to mols H2. 4. Convert psi to mm then use PV = nRT and solve for V in liters. Post your work if you get stuck.

Chemistry
Of your two answers which is correct in your opinion? If you will post your work I will check it. My first run through I didn't get either answer. Remember Ms. Sue. Please use the same screen name. It helps us help you easier (and faster).

chemistry
And what, pray tell, is the molarity of the I2 solution used. As posted this is not workable.

Chemistry
2CH3OH + 3O2 ==> 2CO2 + 4H2O

Chem
1 mole contains 6.023E23 atoms.

Chemistry
yes

Chemistry
With two anonymous names I don't know the difference; however, I assume the first one is answering the question 2 and the others one is saying s/he doesn't know how to use it. q = heat gained m = mass water. 100 mL water has a mass of 100 grams. c = specific heat water...

chemistry
mols FeS = grams/molar mass = ? There is 1 mol Fe in 1 mol FeS.

chemistry
I think the response by Collee2 is hogwash. It makes no sense what-so-ever. There are several reasons to separate solids from liquids. One is that you may wish to have a "pure" solid or a "pure" liquid.

chemistry
Yes, Al is the anode (electrons flow FROM the anode) and Fe is the cathode (electrons flow TO the cathode).

chemistry
1 mol Ag will give you 1 mol AgNO3 which will give 2 mol AgCl. Convert grams AgCl to grams Ag. mm = molar mass; am = atomic mass. grans AgCl x (am Ag/mm AgCl) = ? Then % Ag = (mass Ag/mass sample)*100 = ? Post your work if you get stuck.

chemistry
What is the molarity of the initial H2SO4? That's 1.8 g/mL x 1000 mL x 0.3675 x (1/98) = y N = 2*M Then mL1 x N1 = mL2 x N2 mL1 x yN = 500 x 3N Substitute and solve for mL1.

chemistry
See your other post.

chemistry
25% HCl means 25 g HCl in 100 g solution. volume of 100 g solution is mass/density. Substitute and solve for volume in mL, convert to L. Calculate mols HCl from grams HCl/molar mass HCl. Then M HCl = mols HCl/L solution. pH = -log(HCl) pH + pOH = pKw = 14. You have pH and pKw...

chemistry
mols NaOH = M x L = ? mols HCl = mols NaOH M HCl = mols HCl/L HCl. Convert mols to grams for g/L. g HCl = mols HCl x molar mass HCl.

Chemistry
http://www.chemteam.info/Redox/Redox.html

Science
6.00 g/cc is right. mass = v x d mass = 200 cc x 0.250 g/cc = ?

Chemistry Lab
1. Which alum are you preparing? There are several. You can read about them here. https://en.wikipedia.org/wiki/Alum Generally, a monovalent cation sulfate with a trivalent cation sulfate + 12 mols H2O of crystallization. K, Na, Al, Fe, Cr, etc. I don't know what you used...

Physical Chemistry
https://viziscience.com/chemistry-mole-concept/molarity-change-temperature/

Chemistry
molecular equation: CoCO3 + 2HI==> CoI2 + CO2 + H2O Turn this into an ionic equation. CoCO3(s)+ 2H^+ + 2I^- ==> Co^2+ + 2I^- + CO2 + H2O Net ionic equation: Cancel those ions that appear on both sides of the equation. What's left is the net ionic equation.

1 Out Of 100 Math Trick HELP PLEASE!!!
My dad taught me this trick when I was about 15 but WARNED me that to make it work the number you multiply and divide it by must be the same. There must be some other caveats too.

Chemistry
1 ppm = 1 mg/L For Zn, toxic level is 6.42E-2 mM. That is 6.42E-5 M = 6.42E-5 mols/L. So in 1 L solution we have 6.42E-5 mols and grams Zn = mols Zn x atomic mass Zn and that gives you grams Zn/L. Convert to mg Zn/L and that is that many ppm. grams Zn = m

Chemistry
Tricky...I don't want to write out ethylene glycol all the time so let's let eth stand for that. M solution = mols eth/L solution. How to get values to plug in. mols eth = gram/molar mass and you get grams from mass eth = volume eth x density eth. You know volume and ...

Chemistry
M = mols/L How many mols KCl are there? mols = grams/molar mass = ? How2 many L are there? That's mass H2O = volume H2O x density H2O. Solve for volume in mL and convert to L.

Chemistry
They are not related. Radio waves, x-rays, red light, green light, yellow light, travel at the same speed of 1E8 m/s. It is a general question but you are supposed to know that the speed is the same.

Chemisty
Ionic solutions conduct electricity very well if they are 100% ionized or weakly if not 100% ionized. Covalent compounds that don't ionize3 don't conduct electricity.

Chem
1 ppm = 1 mg/L

Chemistry
Then you made a math error because 3.00 x 0.175 = 25.0 x M2 solves to M2 = 3.00 x 0.175/25.00 and that's the same as 0.175 x 3.00/25.0 = ?

Chemistry
I use this. 0.175 M x (3.00/25.0) = ? You can use the dilution formula of mL1 x M1 = mL2 x M2 3.00 x 0.175 = 25.0 x M2 and solve for M2. Both will give you the same answrs.

oops--chemistry
I see I can't spell phosphorus either.

chemistry
Please note that P is spelled posphorus

chemistry
You may not have done it wrong depending upon what the units were. Na2O + 2HNO3 ==> 2NaNO3 + H2O You want 0.5 mol NaNO3; how much Na2O is needed? So 0.5 mol NaNO3 x (1 mols Na2O/2 mol NaNO3) = ? molNa2O. Then grams Na2O = mols Na2O x molar mass Na2O.

chemistry
Na2O + 2HNO3 ==> 2NaNO3 + H2O 1. 1.5 what? grams? tons? bushels? I didn't get 1.5 grams. 3. 00416 what? Show your work.

Chemistry
You need to know the solubility rules. Here is a set. https://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Equilibria/Solubilty/Solubility_Rules

Chemistry
I still want to know what your problem is in doing this.

chemistry
I would choose something like 50,000 J/mol for Ea, use the Arrhenius equation, and solve for k(rate). Then multiply k by 3D8 and calculate the new Ea. Compare the two.

chemistry
Use the Arrhenius equation. Pick a number, for example choose 50,000 J/mol for Ea, the redo the equation using 50,000-9000 = ? J/mol and see the ratio of the two k values you calculated. That will be the ratio (factor) you want.

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