Tuesday
January 27, 2015

Posts by DrBob222


Total # Posts: 46,587

chemistry
Why are you having trouble converting units? 1 m = 100 cm You have the conversion factor for m to nm. Have you ever seen one of these sodiujm vapor lamps? (I'm sure you have--They are yellow) f = frequency in Hz w = wavelength in m c = speed of light = 3E8 m/s Substitute ...
November 30, 2014

CHEM
Look up the reductions potentials and see which half cell reacts.
November 30, 2014

Chemistry
1. c won't do it. Count the charge. On the left there is 14+ (from 14H^+) + 2- (from Cr2O7^2-). On the right there is 2*3 = 6+. So you Add 6e to the left side. 2. b won't get it. In redox reactions electron gain is ALWAYS ALWAYS ALWAYS = electrons lost (if the equation...
November 30, 2014

Chemistry
Go to Google and type in"activity series". The metals at the top are the top reducing agent. Metal ions at the bottom are the top oxidizing agents.
November 30, 2014

chemistry-chemical equations
Cu + HNO3 ==> Cu(NO3)2 + NO2 + H2O Can you balance it? Cu goes from zero oxidation state on the left to +2 on the right. N (in HNO3) goes from +5 on the left to +4 on the right (in NO2)
November 30, 2014

Chemistry
I assume that is 1.5% NaCl w/v; if so then you have 1.5g NaCl/100 mL solution. That is the same as 15g NaCl/L solution and that has a molarity of 15/58.44 = approx 0.257. So you are diluting 0.257M NaCl from 1.0 mL to 100 mL. New molarity is M = 0.257 x (1 mL/100 mL) = ?M
November 30, 2014

chemistry
I would convert the measurements to cm; therefore, 300 cm x 275 cm x 250 cm = 2.06E7 cc. Convert cc to L = 2.05E7 cc x (1L/1000cc) = approx 2.06E4 L but you need to confirm all of these numbers and if needed with more accuracy. Then PV = nRT. Substitute 10.7 torr(converted to ...
November 30, 2014

Chemistry
I doubt I can help find such a video; however, in this case I don't know what I'm looking for. You didn't give the reaction or the chemical formulas.
November 30, 2014

Chemistry
%abundance Br79 is 50.54% Other isotope Br is 100-50.54 = 49.46% (78.904*0.5054) + (mass*0.4946) = 79.904 Solve for mass (other isotope) = ?
November 30, 2014

Chemistry (Titrations)
No, no, Bridget. That will not work in this case BECAUSE 1 mol Fe is not = 1 mol MnO4^-. 1. Write and balance the equation. Fe(NH4)2(SO4)2.6H2O + KMnO4 + H2SO4 ==> Fe2(SO4)3 + (NH4)2SO4 + K2SO4 + MnSO4 + H2O 2. Convert 0.2848g Fe(NH4)2(SO4)2.6H2O to mols. mol = grams/molar ...
November 30, 2014

Chemistry
This is a limiting reagent (LR) problem and you know that because amounts are given for BOTH reactants. mols Zn = grams/atomic mass = ? mols HCl = M x L = ? Using the coefficients in the balanced equation, convert mols Zn from above into mols H2. Do the same for mols HCl to ...
November 30, 2014

chemistry
mols Ca(OH)2 = M x L = ? Convert mols Ca(OH)2 to mols HClO4 using the coefficients in the balanced equation. Then M HClO4 = mols HClO4/L HClO4. You know mols and M HClO4, solve for L HClO4 and convert to mL.
November 30, 2014

Chemistry
a. Use PV = nRT and solve for n = number of mols O2. mols NO = grams/molar mass = ? Step 2. Using the coefficients in the balanced equation, convert mols O2 to mols NO2. Do the same for mols NO to mols NO2. It is likely that the two values will not be the same which means one ...
November 30, 2014

Chemistry
super
November 30, 2014

Biochem
I am unable from your post to know exactly what you're doing; however, in a hydrolysis of an ester you produce an alcohol and an acid. I would assume that the NaOH titration is to determine how much acid (total, not just HCl) has been produced. My best guess is that the ...
November 30, 2014

Chemistry
See your last post. You also need to convert 36F to C AND you must know the initial temperature of the water.
November 30, 2014

Chemistry
You need to look up the delta H solution of NH4NO3. It probably will be listedin kJ/mol. Convert 8g to mols and multply by delta H to find q for this problem. Then -q = (mass H2O X specific heat H2O x (Tfinal-Tinitial) Solve for Tf
November 30, 2014

introductory chemistry essentials
new M = 5.8M x (3.5/55) = ?
November 30, 2014

Chemistry
I can't read the values you have in the table because of the problem with spacing on this forum but here is what you do. dSo = (n*dS products) - (n*dS reactants) dH you have but it can be done the same way. After you have dSo rxn and dHo rxn, then' dGorxn - dH - TdS.
November 30, 2014

Chemistry
An ICE chart makes it easier, I think, to see. You have written the equation for the dissociation constant for the complex, the number given is a formation constant; therefore, I will rewrite it as (and note that the charge on the complex ion is 3- and not 3+.) The easier way ...
November 29, 2014

chemistry
% w/w (by mass) = (mass solute/mass solution)*100 = ? mass solute = 3.10g mass solution = 3.10g + 10.4g = ?
November 29, 2014

Chemistry
1.40 x (75.0/248) x [124/(124+165)] = ?M
November 29, 2014

Science
q1 for raising T of ice from -15 to zero C is q1 = mass ice x specific heat ice x (Tfinal-Tinitial)= ? (and I would work this as a separate step since you have all of the numbers and put that number for q1 below ) q2 to melt ice is q2 = mass ice x heat fusion = ? (Again, you ...
November 29, 2014

Science
What specific heat are you to use for liquid H2O?
November 29, 2014

chemistry
3.3% by mass means 3.3g Ag/100 g solution. The density of the solution is 1.02 g/mL so 3.8L (3,800 mL) has a mass of 1.02 g/mL x 3800 mL = 3876 g. (x g Ag/3876)*100 = 3.3 x g Ag = approx 128 g. That's an estimate.
November 29, 2014

Chemistry
The combustion of benzoic acid is C7H6O2 + 15/2 O2 ==> 7CO2 + 3H2O and since you want the enthalpy of FORMATION (and not combustion), reverse the equation (and the sign for dH combustion) to obtain 7CO2 + 3H2O ==> C7H6O2 dH = +3223.6 kJ Then dHrxn = (n*dHf benzoic acid...
November 29, 2014

Chemistry
Convert 1.60 mg K2Cr2O7 to mg C2H5OH as follows: mols K2Cr2O7 = 0.00160/molar mass K2Cr2O7. Using the coefficients in the balanced equation, convert mols K2Cr2O7 to mols C2H5OH. That's mols K2Cr2O7 from above x (3 mols C2H5OH/2 mols K2Cr2O7) = mols K2Cr2O7 from above x (3/...
November 29, 2014

chemistry
Use the Henderson-Hasselbalch equation. Sodium benzoate is the base and benzoic acid is the acid.
November 29, 2014

Radiation therapy
I don't think it's A and I don't think it's c. Fuel for what(c). What chemical reaction(A)?
November 29, 2014

To Liz---Chemistry
Your answer is quite correct but let me point out that your solution works ONLY when the reactants are 1:1; if they are not 1:1 you must use the longer process I used. I don't like to use the short answer(as you did) because students then get the idea that it is a general ...
November 29, 2014

Chemistry
The problem you have is you didn't substitute right. mols = 0.235; L = 0.350. M = mols/L. M = 0.325/0.350 = about 0.9M
November 29, 2014

Chemistry
It's really quite simple but I would like to correct a minor point on the equation. (I'm picky and that's why I bring it up.). Your statement, "The stoichiometry is already correct and does not need to be balanced." is not quite correct. That statement ...
November 29, 2014

Chemistry
It's acidic because the (H^+) is greater than 1E-7M and it's important that you draw that comparison; otherwise, I could ask if a solution of (H^+) was 4.3 x 10-10. If you base your answer on the word (H^+) you would be wrong because (H^+) of 4.3E-10 has a pH of 9.4 ...
November 29, 2014

Chemistry
Yes, except you have too many places in yur answer. You are allowed only two places (from the 0.053 which has two significant figures and the 5.0 has two s.f.). Therefore, you should round the final answer to two s.f. and that would be 15.(written 15. or 1.5E1).
November 29, 2014

Chemistry
0.053M means you have 0.053 mols NaCl/Liter of solution. Since M = mols/L you can rearrange that to M x L = mols and 0.053 x 5L = ? mols in 5L of solution. If you want to convert that to grams it is grams = mols x molar mass = ?
November 29, 2014

Chemistry
You can go about this two ways. (g solute/ mL)*100 = % (g CaCO3/250 mL)*100 = 5% Solve for g CaCO3. The other way is that 5% w/v means 5g CaCO3 in 100 mL, you want 250 so 5g CaCO3 x (250/100) = g needed for 250 mL instead of 100 mL. By the way I don't think this is ...
November 29, 2014

chemistry
Your process is correct and the answer would be correct but you threw away part of the answer in the 0.07. You're allowed 3 significant figures by the 4.50 so you don't round the 0.0714 answer you should have obtained to 0.07. In fact, I like to keep one extra place ...
November 29, 2014

chemistry
Use PV = nRT n = mols N2 = grams/molar mass
November 29, 2014

Chemistry
You set it up anyway you wish. If p1 = 744-17.35 = 726.45 (but I get closer to 726.65) then v1 = 495 mL and T1 = 273 + 20 = ?K If you do it that way then P2 is 760 V2 = ? T2 = 273 but you could turn all of that around. The point is that it makes little difference if you solve ...
November 29, 2014

Chemistry
You've done well so far. Now use (P1V1/T1) = (P2V2/T2) and solve for final volume. Remember to round the final answer to the correct number of significant figures, expecially if your prof is picky about that kind of thing.
November 29, 2014

science
volume = width x length x height = ? cubic meters density in kg/m^3 = 45/? = x? If you want it in other units I recommend you convert m to cm and kg to g then units will be in g/cc.
November 29, 2014

chemistry
(NaOH) = 2M x (2 mL/100 mL) = ? (OH^-) = (NaOH) pOH = -log(OH^-) pH + pOH = pKw = 14. You know pOH and pKw, solve for pH.
November 29, 2014

chemistry
HCl + NH3 ==> NH4Cl b) millimols NH3 = M x mL = approx 12.5 but you need to confirm this an all of the calculations that follow. Then millimols HCl needed = 12.5 M HCl = millimols/mL = 0.5. Solve for mL = mmols/M = 12.5/0.5 = about 25 mL. a) You have pure NH3 at the ...
November 29, 2014

chemistry
I'll help you through this but please explain what you know to do and especially what you don't understand about the problem.
November 29, 2014

Chemistry
Write and balance the combustion equation for ethanol + O2 ==> CO2 + H2O as eqn 1. Then reverse that equation multiply it by an integer to make mols CO2 cancel with mols CO2 in the next equation you write (also, change the sign for delta H and multiply by the same factor ...
November 28, 2014

Chemistry
Look up the delta Ho formation of each. (Al is zero but the others have numbers for each.) Then dHrxn = (n*dHformation products) - (n*dH formation reactants_
November 28, 2014

Chemistry
Show your work and I'll find the error. n CO2 = grams/molar mass
November 28, 2014

Chemistry
You do it all with an ICE chart. ...........2NO ==> N2 + O2 I........0.160.....0.....0 C..........-2x.....x.....x E.......0.160-2x...x.....x Substitute the E line into the Keq expression and solve for x and 0.150-x. Post your work if you get stuck.
November 28, 2014

Chemistry
dHrxb = (n*dHformation products)-(n*dHformation reactants)
November 28, 2014

chemistry
1 cubic micrometer = 1E-15 L.
November 28, 2014

chemistry
You're close and your process is right but the math is a little off. By the way, that's dihydrate and not dehydrate. The formula of the dihydrate is CuCl2.2H2O; therefore, you should have added in 2 mols H2O and not 1. The molar mass of CuCl2.2H2O is closer to 170. ...
November 27, 2014

Chemistry
total heat needed = heat to raise Cu kettle + heat to raise the water. total q = [(mass Cu kettle x specific heat Cu x (Tfinal-Tinitial)] + [(mass H2O x specific heat H2O x (Tfinal-Tinitial)] Solve for total q.
November 27, 2014

Chemistry
I don't know what "compose the micelle" means; however, if you could find the caps key and use it, the products in the equation are correct and it is balanced but be aware that agno3 and AgNO3 are not the same.
November 27, 2014

chemistry
Any test you run in a med tech lab will be a practical application. A1C, fasting glucose, lipids, BUN, etc.
November 27, 2014

chemistry
d is correct.
November 27, 2014

Chemistry
dG = dHfus - Tfusion*dSfusion 0 = ..... Then dHfusion = Tfusion*dSfusion.
November 27, 2014

chemistry
Isn't that A? dG = dH - TdS. If dH is - and dS is +, then -TdS will be negative; thus dG will ALWAYS be negative.
November 27, 2014

Chemistry
0.12 dm^3 x (1 mol/24 dm^3) = ? mols N2 mols Cu = ? mols N2 x (3 mols Cu/1 mol N2) = ? Then g Cu = mols Cu x atomic mass Cu = ?
November 26, 2014

chemistry
See your other post.
November 26, 2014

chemistry
I don't think there is a chemical reaction for shampoo. Shampoo is largely a group of cleansing agents mixed together.
November 26, 2014

Chemistry
molecular equation is 2Na3PO4(aq) + 3MgCl2(aq) ==>Mg3(PO4)2(s) + 6NaCl(aq) total ionic BUT you add the phases. 6Na^+ + 2PO4^3- + 3Mg^2+ + 6Cl^- ==> Mg3(PO4)2(s) + 6Na^+ + 6 Cl^- net ionic. cancel those ions that appear on both sides of th equation and you will be left ...
November 26, 2014

Chemistry
Your other post under Kate should give you some hints on how to do this. The spectator ions are the ionx that ARE NOT in the net ionic equation.
November 26, 2014

CHEMISTRY
Cu^2+ ==> Cu you balance. NH3 ==> N2 you balance
November 26, 2014

CHEMISTRY
Can you be more specific. This is a bit too general for me to know where you're trying to go.
November 26, 2014

chemistry
One qual application is for a business to analyze a competitors product to see what it contains. One quant application is. Almost every food product on the market must show on the label the contents of the container. Almost every manufacturer or every product I know must have ...
November 26, 2014

CHEMISTRY HELP
Do you have any thoughts on the subject?
November 26, 2014

chemistry
When dG is negative the reaction is spontaneous.
November 25, 2014

chem please help
I agree with c.
November 25, 2014

chemistry
Use PV = nRT; solve for P
November 25, 2014

chemistry
right, b is the answer.
November 25, 2014

chemistry
c is the answer. For my money I wish physics had kept it.
November 25, 2014

Chemistry help drbob222
I agree with d.
November 25, 2014

Chemistry
This is just another stoichiometry problem like the HNO3/NO problem below with a slight twist. Solve for theoretical yield in grams, as before, then %yield = (AY/TY)*100 = 94.5 and solve for AY.
November 25, 2014

Chemistry
mols H2O = grams/molar mass Using the coefficients in the balanced equation, convert mols H2O to mols NO. Convert mols NO to g. g NO = mols NO x molar mass NO. This is the theoretical yield (TY). The actual yield (AY) is 125g. % yield = (AY/TY)*100 = ?
November 25, 2014

Chemistry
delta T = Kf*m. You know delta T (normal freezing point - new freezing point) and Kf, solve for m = molality. m = mols/Kg solvent. You know m and kg solvent (use density for kg solvent; i.e., mass = volume x density). solve for mols. mols = grams/molar mass. You know mols and ...
November 25, 2014

POTASSIUM SULPHATE FERTILIZER GRANULE PROCESS
What's the concentration of the HCl?
November 25, 2014

chemistry
I will assume you intended to write 0.3m, meaning 0.3 molal since you don't seem to be able to find the caps key on your computer. m = mols solute/kg solvent 0.3 = mols BaCl2/0.150 Solve for mols BaCl2, then mols = grams/molar mass. You know molar mass and mols, solve for ...
November 25, 2014

chemistry
Why all the screen names? Work this one the same way when your name was Destiny.
November 25, 2014

chemistry
See Destiny et al.
November 25, 2014

chemistry
See your other screen names.
November 25, 2014

chemistry
mols = M x L = ?
November 25, 2014

chemistry
See your post under Mackenzie.
November 25, 2014

chemistry
See your other screen names posts.
November 25, 2014

chemistry
Done the same way no matter what your screen name is. See those posts.
November 25, 2014

chemistry
At least you came up with a different kind of problem. M = mols/L solution.
November 25, 2014

Chemistry
Check this to confirm. CuSO4 + 6NH3 + 2H2O = (NH4)2SO4 + Cu(NH3)4(OH)2
November 24, 2014

chemistry 2
The long way is to use PV = nRT and solve for pressure of each gas. n = grams/molar mass or atomic mass when dealing with grams. Then add the partial pressures to find the total pressure.
November 24, 2014

Chemistry
mols = M x L = ? Then mols x molar mass = grams.
November 24, 2014

Chemistry
C + O2 ==> CO2 393.5 kJ x (6g/12g) = kJ heat released to burn 6g C. X grams C = 12 x (39.3/393.5) =
November 24, 2014

Chemistry
........H2 + I2 ==> 2HI E.......x..0.015....0.030 Plug into the Keq expression and solve for x.
November 24, 2014

chemistry-naming
C3H8 probably is propane. KCl is potassium chloride
November 24, 2014

Chemistry
0.60 M Na^+. There are 3 Na atoms in 1 Na3PO4 molecule; therefore, (Na3PO4) must be 0.60/3 = 0.20M Na3PO4.
November 24, 2014

Chemistry
I think Damon worked this below.
November 24, 2014

Chemistry
http://www.nwscc.edu/nsfdc/organicchemistry/constitutional%20isomers
November 24, 2014

chemistry
No and I answered no to the response I gave yesterday. One reason you know 105g can't be correct is because to obtain 160.9 g Au from AuCl3, the AuCl3 must be more than 160.9g because AuCl3 is not 100% Au.
November 24, 2014

chemistry
Frankly, I think the whole idea of valence electrons with transition metals is nonsense unless the rules make sense and most don't. I've spent almost two hours looking at page after page for an explanation of valence electrons. No two sites give the same rules for ...
November 24, 2014

CHEMISTY HOMEWORK HELP ASAP
1. Use the Henderson-Hasselbalch equation. Substitute into the HH equation and calculate pH. 2. Set up an ICE chart using .......CH3COOH + OH^- --> CH3COONa + H2O and substitute the E line of the ICE chart into the HH equation and sole for the new pH.
November 24, 2014

Chemistry Homework Help Please!
See my response above.
November 24, 2014

Chemistry
NaF is the base HF is the acid.
November 24, 2014

Chemistry
millimols NaF = mL x M = approx 100 mmols HF = mL x M = aprox 62.5 mmols HCl added = approx 3.75 You omitted the exponent on Ka. I think that's 7.1E-4, then pKa = 3.14 ................F^- + H^+ ==> HF I..............100....0.......62.5 add.................3.75 C...
November 24, 2014

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