# Posts by DrBob222

Total # Posts: 55,199

Chemistry
See this link. Read down the right side table to solubility. It gives solubility at three temperatures and shows an increase. https://en.wikipedia.org/wiki/Calcium_iodate

chemistry
Use the dilution formula. %1*mL1 = %2*mL2 10*mL1 = 0.5*50 Solve for mL1 of the 10% stock solution, pipet that quantity into a 50 mL volumetric flask, add DI H2O to the mark, mix thoroughly, stopper and viola!

Chemistry
ln(Ao/A) = kt If you use k as listed than t is 5 min x (60 s/min) = 300 s. Solve for A

chemistry (ap)
You don't have enough information listed.

CHEMISTRY

Chemistry
mols HCl = grams/molar mass = approx 0.3 but that's an estimate. Then M HCl = approx 0.3/5L = about 0.06 pH = -log (HCl) = ?

chemistry
dE = 2.180E-18[1/(n1)^2 - (1/(n2)^2] n1 = 1 and 1^2 = 1 n2 = 5 and 5^2 = 25

chemistry
I don't see a question here.

Chemistry
Use the De Broglie equation but first convert the mass to kg and the wavelength to m.

Chemistry

Chemistry
One thing you could have done is to provide the possible answers. An aliquot is the way to go. Without knowing the details I can only generalize. What you want to do is to take an aliquot of the sample. Apparently you are titrating into a 10 mL graduated cylinder, or at least ...

Chemistry
And you haven't come close to providing enough information for us to know what the problem is.

BIOCHEMISTRY
You need two equations to solve simultaneously. Equation 1 is the Henderson-Hasselbalch equation. pH = pKa + log (base)/(acid) 5 = pKa + log (base/acid) Substitute and solve for ratio (base)/(acid). Equation 2 is (acid) + (base) = 0.2 M Solve the two equations for (base) and (...

Chemistry
If you assume this is an ideal solution. Take 100 g solution. mass acetone = 5g mols acetone = 5/molar mass = ? mass H2O = 95 g mols H2O = 95/molar mass H2O = ? total mols = mols acetone = mols H2O = ? Xacetone = mols fraction acetone = nacetone/total mols xH2O = nH2O/total ...

Chemistry
rate1 = 0.33/s for T1 = 29C (302 K) rate2 = 0.27/s for T2 = 23 (296 K) rate1 = k1(A) rate2 = k2(A) Calculate k1/k1 knowing rate1 and rate2. (A) is constant. ln(k2/k1) = Ea(1/T1-1/T2)/R Substitute and solve for Ea.

Chemistry
At what T? Ne is a gas at room T and quite a bit below room T.

@coolest
I responded to your question above. Please don't post questions piggy back. Most of that type never gets and answer.

Chemistry
Fe + S ==> FeS mols S = grams/atomic mass S = ? Convert mols S to mols FeS. Look at the equation. See that 1 mol S forms 1 mols FeS. Then grams FeS = mols FeS x molar mass FeS.

Chemistry
mols O2 = grams/molar mass O2 = ? Using the balanced equation, convert mols O2 to mols H2O. You can seee that 1 mol O2 requires 2 mols H2O. Then convert mols H2O to grams H2O. grams H2O = mols x molar mass = ?

CHEM 114
Sure, why not. You have two reactants, each can be first order, which makes the total reaction second order.

Chemistry
0.01m/s x (39 in/m) x (1 ft/12 in) x #sec = 8 ft Solve for # sec.

Chemistry

Chemistry
Note the correct spelling of Celsius. delta T = i*Kf*m i for urea = 1 Kf for H2O = 1.52 You know delta T = 4. Solve for m = molality Then m = grams/kg solvent You know kg solvent and m, solve for grams.

chemistry
This is at least an hour's worth of explaining. Surely you know how to to portions of this. How what you know how to do, explain what you don't understand, and I can help you through with the rest of it.

Chemistry
If you want to do this exactly, you will need to know the masses of the isotopes; i.e., they are not exactly 25, 26, and 24. The problem is done this way. Let x = abundance 25 Then 1.00-0.79-x =0. 21-x = abundance 26. (0.79*24) + (x*25) + (0.21-x)*26 = 24.3 You will need to ...

Chemistry
I assume you have aqueous solutions of both. molecular equation: Sr(NO3)2(aq) + Na2CO3(aq) ==> SrCO3(s) + 2NaNO3(aq) Net ionic equation: Sr^2+(aq) + CO3^2-(aq) ==> SrCO3(s)

chemistry
NH4NO3 ==> N2O + 2H2O The problem tells you it is a decomposition reaction.

chemistry
mols K2CrO4 = M x L = ? Using the coefficients in the balanced equation, convert mols K2CrO4 to mols PbCrO4(hint: 1 mol K2CrO4 = 1 mol PbCrO4) Then convert mols PbCrO4 formed to grams by g = mols x molar mass = ?

chemistry
If done in detail this will take 10-15 pages of explanation. Surely you know how to do parts of this. I can help you through the parts you don't understand but show what you can do first.

chemistry
2Na + Cl2 ==> 2NaCl 2 mols Na x (1 mol Cl2/2 mols Na) = 2*1/2 = ?

chemistry
See above

Chemsity
http://www.cod.edu/people/faculty/jarman/richenda/1551_hons_materials/Activity%20series.htm The METAL will oxidize any ION below it in the activity series.

chem
...AgCl(s) ==> Ag^+(aq) + Cl^-(aq) I..solid.......0...........0 E..solid.....1.35E-5.....1.35E-5 Ksp = (Ag^+)(Cl^-) = (1.35E-5)^2 = ?

chemistry
grams HCl in 1000 mL is 1.18 g/mL x 1000 mL x 0.37 = approx 437 g but that's just an estimate. Then mols in that 1 L = grams/molar mass = approx 437/36.5 = about 12 M, another estimate. Since that is mols/L that is M. b. g HCl = mols HCl x molar mass HCl so g HCl = 0.315 x...

oops---Chemistry
I think this question should be reviewed and/or rethought. a. mL x N x milliequivalent weight = grams. 500 x 4 x (98/3000) = about 65 g. b. 8N is right c. There is a typo here. 600*20 = 12,000 mL or 12 L. d. mols = M x L = 6 x 0.3 = 1.8 mols. Then grams = mols x molar mass = 1...

Chemistry
C6H12O6 + 6O2 ==> 6CO2 + 6H2O + 15.7 kJ dHfrxn = (n*dHf products) - (n*dHf reactants) 15.7 kJ/mol = [(6*dH CO2)+(6*dH H2O)] - (0 + dH glucose). Solve for dH glucose.

chemistry
I agree with the response by v. Here is another way of saying the same thing. Li has +3 charge in nucleus and 2e in the first energy level; therefore, the outside electron "sees" +1 charge. Na has 11+ charge in nucleus and the outside electrons "sees" 1&...

chemistry
HCl + NH3 ==> NH4Cl millimols HCl = mL x M = 25 x 0.1 = 2.5 mmols NH3 = 2.5 so volume must be 25.0 mL. Total volume - 50 mL. M NH3 = mmols/mL = 2.5/50 = 0.05 M. The pH at equivalence point is determined by the hydrolysis of the NH4Cl. .......NH4^+ + H2O ==> NH3 + H3O^+ I...

Chrmisty
HF + NaOH ==> NaF + H2O millimols HF initially = mL x M = 25 x 3 = 75 mmols NaOH added = 25 x 0.3 = 7.5 mmols HF left un-neutralized = 75-7.5 = 67.5 volume of new solution = 26 mL + 25 mL = 50 mL. M HF left = mmol/mL = 67.5/50 = 1.35 M. ......HF ==> H^+ + F^- I....1.35...

Chemistry 112
A little tough on this site but it would be easier to do if you posted the data.

Chemistry
4 g He will occupy 22.4L at STP. So 1g will occupy .......?

Chemistry
Use the Henderson-Hasselbalch equation.

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).

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.