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Posts by DrBob222

Total # Posts: 54,752

Chemistry
Been to Hawaii. Left on 18. Just got back minutes ago.

Chem
There must be thousands of books written on water analysis. Filtered water? sea water? what ions? Look up zeolites. Look up ion exchange resins.

chemistry
dH rxn = (n*dHo products) - (n*dHo reactants)

Chemistry
dH rxn = (n*dHo products) - (n*dHo reactants).

chemistry
(HNO3) = 3M x (6 mL/18,000 mL) = ? Then pH = -log(HNO3); however, be careful that this concentration is so small that you must include (H^+) from the ionization of water. Post your work if you get stuck.

Chemistry
I don't know the size of a basket ball. You estimate the diameter. Radius will be 1/2 that. Volume = (4/3)*pi*r^3 Then mass = volume Hg x density Hg

chemistry
E in joules = -2.180E-18/N^2

Chemistry
Any time you have a reaction it is chemical. If a new substance is formed it is chemical. Reactions that produce heat are exothermic. Reactions when T goes down are endothermic. Rust and magnetic. see https://www.google.com/search?q=is+ability+to+rust+chemical+or+physical+...

Chemistry
A ppt of BaSO4 forms. BaCl2 + Na2SO4 ==> BaSO4(s) + 2NaCl

Chemistry
pOH = -log(NaOH) Then pH + pOH = pKw = 14. You know pKw and pOH, solve for pH.

chemistry
ethanoic acid is CH3COOH or HAc. K2CO3 + 2HAc ==> 2KAc + H2O + CO2 mols K2CO3 = M x L = ? mols HAc = 2*mols K2CO3 (you get that form the coefficients in the balanced equation). Then M HAc = mols HAc/L HAc = ?

chemistry
delta E = 2.180E-18(1/1^2 - 0)

chemistry
Can't you just plug in the numbers and solve it. The problem gives you the equation as well as the numbers. It's just a matter of punching in the numbers into the calculator. rate = 0.004*(0.020)^2(0.035) Solve for rate.

chemistry
This is just another dilution problem. millimoles KIO3 initially (and finally) = mL x M = ? Then final concn = mmols/mL = ?mmols from above/10 mL = ?

@anonymous--chemistry
Better think again.

chemistry
This is just another stoichiometry problem. 0.6 x (2 mol NH3/1 mol N2) = ?

chemistry
rate1 = k1(A)^x --------------- rate2 = k1(A)^x You know k1 and k2 are the same so they cancel. rate1 = 0.50; (A) = 1.0M rate2 = 0.25; (A) = 0.50 Substitute 0.50 = (1.0)^x -------------- 0.25 = (0.50)^x Solve. 2 = 2^x So x must be what?

chemistry
delta C = 0.12-0.09 = ? time = 20s - 10s = ? Avg = delta C/delta t = ?

Chemistry
I am not an expert on corrosion testing but I don't think it is necessary to try the REAL material in use; i.e., a small 1" or 2" square is taken and the test is done on that piece. In other words, that is a throw away piece and not a piece of the original ...

CHEMISTRY
mols NaCl = grams/molar mass = ? Then M = mols/L

chemistry
How many d sub-shells are there? 5? If those have only 1 electron then how many electrons can be there?

stiochemetry
How many mols do you need? That's M x L = mols Then mols = grams/molar mass. You know mols and molar mass, calculate grams.

Stem
HNO3 + NaOH ==> NaNO + H2O millimols HNO3 = 30 x 0.1 = 3.00 millimols NaOH = 20 x 0.1 = 2.00 millimols HNO3 in excess = 1.00 M HNO3 = mmols/mL = 1.00/50.0 = ? Then pH = -log(HNO3) = ?

chemistry
(NH4)2CO3 ==> 2NH3 + CO2 + H2O

chemistry
Excuse me but solutions aren't moral or immoral. I suspect you want the molarity although you may want the molality since you have included the density. Here is the way to find molarity = M mols K2CO3 = grams/molar mass = ? and since this is in 1 L of solution, that is the...

chem 11
We can't draw diagrams, figures, etc on this forum. The main differences are in the higher molar mass of CHCl3 and the fact that CHCl3 has more intermolecular forces (it is polar and CH4 is not polar).

chemistry grade 11
You may wish to balance the ENTIRE equation but I'll leave that to you. I'll balance just the part that matters. 5Fe*2+ + MnO4^- ==> Mn^2+ + 5Fe^3+ mols KMnO4 = M x L = ? mols in the 20 mL sample. How many mols KMnO4 will that be in the 500 mL sample? That's ?...

Chemistry
N2 + 3H2 ==> 2NH3 mols H2 = grams/molar mass = ? Convert mols H2 to mols NH using the coefficients in the balanced equation. That's ?mols H2 x (2 mols NH3/3 mols H2) = ? Then convert mols NH3 to grams. g = mols x molar mass = ?

Chemistry
I don't know exactly what you want on some of these. I will answer some but not all of these to get you started. For those I don't answer, please repost and tell me what you don't understand about it/them. NaCl [Symbol] Na + Cl2 Type of reaction: synthesis No. ...

Chemistry
mols NaHCO3 = grams/molar mass = ? Then remember 1 mol of anything contains 6.02E23 molecules.

chemistry
It is mined from the ground. There are numerous sulfur mines in the U.S. and many of those are in Louisiana. Look up the Frasch process on Google. Here is a link. https://en.wikipedia.org/wiki/Frasch_process

Chemistry
Yes.

Chemistry
Yes, and that might be called an intermediate step, with the final step showing the hydratred ions.

Chemistry
The solid NaNO3 is held together by the crystal lattice energy. The Na-NO3 is an ionic bond. When the polar water molecules of water move to the crystal, the positive end of the H2O molecules is attracted to the NO3^- part of the NaNO3 and the negative end of the H2O molecule ...

Chemistry
The NaNO3 and H2O came from the acid/base neutralization of HNO3 and NaOH; i.e., HNO3 + NaOH ==> NaNO3 + H2O The reaction I have written is about 99.999% (or more) complete; therefore there is a <0.001% chance that the reverse reaction, which you wrote first, will occur.

Chemistry
You have posted this question in the last week or so. It is the same question but has taken many different forms. If we knew what was confusing you we might be able to help. HNO3 + NaOH is an acid/base neutralization that essentially goes to completion from left to right. At ...

American government
Note from Bob Pursley's response, that Al2(SO4)3 IS soluble in water and it does NOT form a ppt; therefore, the solution of same is colorless.

chemistry
To paraphrase MathMate's answer, no, it isn't correct. I have used, quite often, the CO example, but I add another. CO is carbon monoxide, Co is cobalt, and co is the abbreviation for company.

Chemistry
Fe + 2HCl ==> FeCl2 + H2

Chemistry
You can do that but usually the word "heat" is written above the arrow. Also, the capital Greek letter "delta" is written above the arrow to indicate that heat is applied to the reaction. Remember the capital Greek letter delta looks like an equilateral ...

chemistry
A modified version of the gas law is P*molar mass = density*RT

chemistry
2HgO ==> 2Hg + O2 mols HgO = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols HgO to mols Hg. That will be mols Hg = mols HgO x (2 mols Hg/2 mols HgO) = mols HgO x 2/2 = ? Then grams Hg = mols Hg x atomic mass Hg = ? Do the same for O2 to ...

Chemistry
How much water? How much gas? Do you have any way of knowing the concentration of the NH3(aq) that was on the paper? Probably not. Whatever pH you obtained is the pH you should get if the paper was the right kind of pH paper.

Concentration of Hydrofluoric Acid
Or experimentally you can titrate the HF solution with a known volume and molarity of a base such as NaOH.

chemistry
I wonder what part a to the question was. You can't do part b without doing part c first. c. (1) g Cu + g CuO = 0.5g (2) g Cu + g Cu + g O = 0.5 g After heating the O is gone so subtract (2) from (1) to get g O = 0.5-0.42 = 0.08 The reduction equation is 2H2 + O2 ==> ...

chemistry
First you must understand that this is not a proper question because Al2O3 is not decomposed by heat. However, this is how you work this hypothetical question. 2Al2O3 ==> 4Al + 3O2 mols Al2O3 = grams/molar mass = ? mols Al produced = 2*mols Al2O3 g Al = mols Al x atomic ...

Chemistry
I think I answered this for you earlier. NaNO3 decomposes on heating the solid to NaNO2 and O2. NaNO2 is a white solid. O2 is a colorless gas.

Chemistry
g Mg changed = 6.00 - 4.50 = 1.50 mols Mg = grams/atomic mass = ? Then rate = delta mols/delta time.

chemistry
...CO3^2- + HOH ==> HCO3^- + OH^- I..0.145..............0......0 C...=x................x......x E.0.145-x.............x......x Kb for CO3^2- = (Kw/k2 for H2CO3) = (x)(x)/(0.145-x) Solve for x = (OH^-)

Chemistry
q = mass Ag x specific heat Ag x delta T. Substitute and solve for dT.

Chemistry
q = mass H2O x specific heat H2O x (Tfinal-=Tinitial) You know mass H2O, you can look up specific heat H2O and you are given Tfinal and Tinitial. Substitute and solve for q and that will be enthalpy for 0.882 g CO or J/0.882. Convert that to J/mol. J/0.882 x (28g/mol) = dH in ...

Chemisty
A limiting reagent (LR) and excess reagent (ER) problem. You know that because amounts are given for BOTH reactants; besides, the problem tell you. Convert 6.25 g NH3 to mols. mols = grams/molar mass Do the same for O2. Using the coefficients in the balanced equation, convert ...

@ Bob Pursley--Chemistry
Sorry I posted too. I was almost through answering when the phone rang and when the conversation was over I didn't check if the question had been answered.

Chemistry
The equation tells you that 2 mols SO2 will generate 197.8 kJ. How much is 2 mols SO2? That's 2*64 = 128 g SO2 will generate 197.8 kJ. So what will 8.54 g do? Set up a ratio/proportion or use reason to do it. Here is ratio/proportion: (128 g/197.8 kJ) = 8.54 g/x kJ). Solve...

Chemistry
The rate of decomposition of the ammonium salt to produce gaseous NH3 is so slow at room temperature that the test for NH3 might be missed; therefore, the solution is heated in order to increase the rate of reaction. For many reactions the rule of thumb is that the rate is ...

Chemistry
Without know the experiment you did I must guess about some of these. 1. Most nitrates decompose when heated to give oxygen gas. 2. I don't knopw either unless you want to make sure the solution is basic. 3. How would you know what gas is liberated if you don't test it...

Chemistry
Good luck. I believe you have too many unknowns.

Chemistry
No. M = mols/L mols = grams/molar mass Substitute and solve for M.

chemistry
????

chemistry
(p1/t1) = (p2/t1). Substitute and solve. You don't have t1 listed.

AP Chemistry!!!
I don't get it. You have it worked out in your mind. Heat lost by Al is q = mcdT. Heat gained by water is q = mcdT. heat lost by Al + heat gained by H2O = 0 so you never need to find q by itself. [5.6 x specific heat Al x (Tf-Ti)] + [mass H2O x specific heat H2O x (Tf-Ti...

Chemistry
Ptotal = pdry ice + pH2O Substitute total land pH2O, then solve for pdry ice.

chemistry
Zn + 2HC2H3O2 ? Zn(CH3COO)2 +H2

Chemistry
I assume table 10-1 lists the density of the materials in the list of possible metals. density = mass in air/(mass in air-mass in H2O)= ? Compare with the numbers in table 10-1

science
https://www.quora.com/Are-there-any-good-conductors-of-heat-that-are-not-metals

chemistry
I don't see a question here.

Chemistry
isotopes

Chemistry
A = kc A = 0.82 k = 6220. Solve for c in mols/L. Correct for the two dilutions; i.e., 1 up to 3 and 1 up to 5 and the answer is in mols/L. Convert that to ng/L, then to ng/100 mL.

Chemistry
Who knows? You don't give any details.

Chemistry
The noble gases.

AP Chemistry!!!
Al ==> Al^3+ + 3e Pb^2+ + 2e ==> Pb Oxidation is the loss of electrons. Reduction is the gain of electrons. Which half rxn above lost and which gained? For the potential of the cell, look up the reductions potentials, change the sign of the Al half cell, add in the ...

Chemistry
Both are done the same way. Here is how to do the first one. How many mols do you need? That's mols = M x L = ? Then mols = g/molar mass. You know molar mass and mols, solve for grams Pb(NO3)2 or NaI needed.

Chemistry (PLZ HELP)
There is nothing wrong with the solution by MathMate of this hypotehtical question. However, I just don't believe Al2O3 will decompose thermally to Al/

Chemistry
20 mL NH3 x 0.5 M NH3 = mL HCl x 0.1 M HCl. Solve for mL HCl.

Chemistry
What's problem 1?

Chemistry
Use the Henderson-Hasselbalch equation.

Chemistiy
I don't get it, the possible answers that is. Voltaic cell is the correct answer to a. Voltaic cell is the correct answer to b.

Chemistry (just need someone to check my answer)
9 mols O2 is correct; I don't see a balanced equation.

chemistry
Use the Arrhenius equation.

Chemistry
When using solid KOH, the volume of the solution doesn't change significantly and delta T will be some value. When adding a solution of KOH, the volume of the KOH will add to that of the HCl; therefore, the heat generated must heat a larger about of water and delta T will ...

AP Chemistry
I don't think you have the right picture. Do it this way. mols WO3 = grams/molar mass = ? Use the coefficients in the balanced equation to convert mols WO3 to mols CO2. Now convert mols CO2 to grams CO2. g CO2 = mols CO2 x molar mass CO2. This gives you the grams of CO2 ...

Chemistry
You're right but I would have done it as (0.68/1.3) = 0.52 = 52%. I'm not being picky, rather, I'm pointing out that if I do it your way I'm doing two operations that are not necessary (multiplying both numerator and denominator by 1000 before dividing) and ...

Chemistry
You have 2 mols Al and 3 mols C and 9 mols O.

Chemistry
Again, I assume this is ppm w/v. Volume of 25 kg seawater is v = m/d = 5000 g/1.025 g/mL = 4878 mL. Then mg Pb/L = ? mg/L = ppm w/v

Chemistry
I assume that is ppm w/v. 5 ppm = 5 g Pb/10^6 g H2O = 5 mg Pb/10^3 g H2O = 5 mg Pb/1000 g H2O = 5 mg Pb/1L H2O if density of H2O is 1.00 g/mL (or 1000 kg/m^)

Organic Chemistry
You might think so since acetone has such as low boiling point; however, I might be worried more that the flask was heated too much in trying to get all of the solvent out. You might try dissolving the solid again in a minimum of solvent, pouring the mixture into a beaker, ...

Chemistry
The longer the chain the more intermolecular forces and the higher the boiling point (lower vapor pressure).

Chemistry
mols Fe ==> grams/molar mass = ? Convert to mols O2. That's ?mols Fe x (3 mols O2/4 mols Fe) = ? Then mols O2 x 22.4 L/mol = L O2

Chemistry
What's an IRF? 2NaOH + H2SO4 = Na2SO4 + 2H2O Convert pH of NaOH to pOH and calculate (OH^-) and (NaOH). Then mols NaOH = M x L = ? mols H2SO4 = M x L = ? Subtract to see which is in excess, calculate (H^+) or (OH^-) as it applies and convert to pH.

Chemistry
Are you sure of that formula? mols = 8.87/molar mass = ? Then M = mols/L. YOu know mols and M, solve for mL.

Chemistry
The carbon dioxide is released from the solution. At room temperature CO2 isn't very soluble in water.

chemistry
If you want to dilute the solution from 5 M to 0.5 M, you must dilute by a factor of 10. You want 100 so take 10 mL and dilute to 100. For this you will need a 10 mL pipet and a 100 mL volumetric flask. 2. Powdered Zn has MUCH MORE surface area so the reaction is faster (MUCH ...

Chemistry
We can't draw structures on this forum. I suggest you google this. Most Lewis structures on on the web.

Chemistry
P*molar mass = density*RT P must be in atm. 760 torr = 1 atm.

Chemistry
I have no idea what the domino format is.

chemistry
https://en.wikipedia.org/wiki/Lead(II)_iodide

Chemistry
You can find the answer easily by googling scintillation counter. Wilipedia is the best sorce, I think, and you should read under "detectors".

Chemistry
I don't think it will change the position at all although your prof may be expecting an answer of D. To make it shift to the left you must add Ag+ or S2- and neither is present in (NH4)2SO4. To shift to the right you must add something that reacts with either product but (...

Chemistry
What's the problem here? Do you know the definition of Keq?

Chemistry
B is not right.

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