Tuesday
September 27, 2016

Posts by DrBob222

Total # Posts: 53,155

chemistry
First you must determine which way the reaction will shift to react equilibrium. That is done with Qc. Qc = (PCl3)(Cl2)/(PCl5) = 0.12*0.12/0.12 = 0.12= Qc and Kc = 0.8 so Qc is too small which means products are too low and reactant is too high so shift must be from left to ...
July 10, 2016

chemistry
Do you mean with "final concentration" you want composition of NH3 or do you want the dissociation components; i.e., NH4^+ and OH^-. I will assume you want final NH3 composition and not the dissociation parts. mols #1 = M x L = ? mols #2 = M x L = ? final (NH3) = ...
July 10, 2016

Chemistry
You need to understand what's happening here. You add an excess of HCl to CaCO3 and it reacts completely but not all of the HCl is used. The NaOH is to determine how much of the HCl excess is there after all of the CaCO3 is gone. CaCO3 + 2HCl ==> CaCl2 + H2O + CO2 ...
July 10, 2016

CHEMISTRY
You had 7.46 grams to begin. You placed that in 1000 cc and pulled out 25 cc of that. So the amount in the 25 cc is all you titrated (you didn't titrate the entire 7.46g sample) so how much sample was in that 25 cc. That's 7.46 x 25/1000 =
July 9, 2016

CHEMISTRY
mass M2CO3 titrated = 7.46 x (25/1000) = approx 0.19 but you need a more accurate number for this and the all of the calculations that follow. M2CO3 + 2HCl ==> CO2 + H2O + 2MCl mols HCl = M x L = approx 0.0027 mols M2CO3 = 1/2*0.0027 = 0.00135 mols = grams/molar mass or ...
July 9, 2016

CHEMISTRY
H2C2O4 + 2NaOH ==> Na2CO2O4 + 2H2O 1.575 g H2C2O4.xH2O in 250 mL and 25 cc of that makes the sample titrated 1.575 x (25/250) = 0.1575grams. mols NaOH = M x L = approx 0.0025 but you need to redo all of this with better numbers. Convert mols NaOH to mols H2C2O4.xH2O. 1/2 * ...
July 9, 2016

science
You can read more about it here. https://en.wikipedia.org/wiki/Lifted_condensation_level height in meters = 125(T-Td) T is 28; Td is 18. Solve for h in meters. I get about 1250 feet.
July 8, 2016

Chemistry
Actually, the problem isn't stated properly. It should spell out if the answer needed is for mols H atoms or mols H2 molecules
July 8, 2016

Chemistry
Pressure in vessel 1 is p1 since the temperature hasn't changed. Pressure in vessel 2 is p2 = p1 x (t2/t1)
July 7, 2016

chemistry
You don't get it????? I responded to this yesterday with the quote that you were a better chemist than I if you can get NaOH from NH3 without doing something to it.
July 7, 2016

Chemistry
The problem is flawed. 18 g C can produce ONLY 66 g CO2.
July 6, 2016

chemistry
I don't understand the question, exactly. This may be what you are talking about. H2SO4 HOSO3H
July 6, 2016

Chemistry
q = mass Cu x specific heat Cu x delta T. Look up specific heat, substitute the numbers and solve for q.
July 6, 2016

Chemistry
The substance oxidized is the one that loses electrons. On the left C is -4 and on the right +4. On the left O2 is zero and on the right -2.
July 6, 2016

chemistry
Would you believe none? No H2 is involved in the equation. In fact the equation is wrong because a. it isn't balanced. b. the product and reactant are the same.
July 6, 2016

AP Chemistry
The three previous posts are all about electrochemistry. They are general with nothing to indicate what your problem is with these. Bob Pursley answered the first one. I'll be glad to help you through these but I'm not inclined to write a chapter or two, which really ...
July 6, 2016

AP Chemistry
From the previous work I'm sure you can see that it is important and why. I shall be happy to critique your thoughts.
July 5, 2016

AP Chemistry
S + O2 ==> SO2 Suppose you have 16 g S and 32 g O2 and they react. mols S = grams/atomic mass = 16/32 = 0.5 mol S. mols O = 32/32 = 1 mol O2. 0.5 mol S requires, from the coefficients in the balanced equation, 0.5 mol O2. Do you have that much O2. Yes, so S is the limiting ...
July 5, 2016

AP Chemistry
Because Mg combines with N2, also in the air, to form Mg3N2. So although most of the product would be MgO, it would be contaminated with some Mg3N2.
July 5, 2016

Chemistry
ASSUMING the acid you're using is 100%, then for 10% v/v you want 10 mL acid/100 mL solution. So scale that up from 100 mL to 2,000 mL. 10 mL x (2000 mL/100 mL) = ? Most acids are not 100%.
July 5, 2016

Chem
Coulombs = amperes x seconds. C = 2 x 16 x 60 = 1,920 For every (63.55/2) g Cu plated it requires 96,500 C. So (63.55/2) x (1920 C/96,500 C) = ?g Cu plated.
July 5, 2016

chemistry
I don't know how advanced this class is. If beginning your prof PROBABLY (I'm guessing) will want you to do this. H2SO4 ==> 2H^+ + SO4^2- So 0.01M H2SO4 gives 2 x 0.01 = 0.02M H^+ and you convert that to pH with pH = -log(H^+). However, it turns out that although ...
July 5, 2016

CHEMISTRY
I don't know how you obtained 998.4 mols. I might believe 0.9984. If you want the answer in tonnes, I would do this. A little unconventional but it saves a lot of work. If we work in tonnes, we never convert 64.0 tonnes to grams. Then we don't need to convert grams ...
July 5, 2016

chemistry
2KClO3 ==> 2KCl + 3O2 mols O2 needed = grams/molar mass = 48/32 = about 1.5? Using the coefficients in the balanced equation, convert mols O2 to mols KClO3. That's 1.5 mols O2 x (2 mols KClO3/3 mols O2) = 1.5 x 2/3 = about 1 So you need 1 mol KClO3 which is grams = mols...
July 5, 2016

chemistry
What about it?
July 5, 2016

Chemistry 1111
NaOH + KHP ==> NaKP + H2O mols KHP = grams/molar mass = ? mols KHP = mols NaOH (the ratio is 1 mol KHP to 1 mol NaOH in the equation). M NaOH = mols NaOH/L NaOH = ? Note: volume NaOH = 24.65 mL - 1.85 mL = ? mL. Convert to L.
July 5, 2016

chemistry
You have made a buffer by reacting NH3 and HCl. I assume "normal" conditions mean STP. mols HCl = 10/22.4 = approx 0.45 mols NH3 = 20/22.4 = approx 0.89 You need to redo all of these calculations. .......NH3 + HCl ==> NH4Cl I....0.89....0.45.....0 C....-0.45..-0....
July 5, 2016

chemistry
This is a hydrolysis equation. M NH4Cl = mols/L = grams/molar mass/L = approx 0.2 but you need to redo all of these calculations. ......NH4^+ + H2O ==> H3O^+ + NH32 I....0.2...............0.......0 C.....-x...............x.......x E.....0.2-x............x.......x Ka for NH4...
July 5, 2016

chemistry
See your other post.
July 5, 2016

chemistry
You're a better chemist than I if you can do that.
July 5, 2016

chemistry
HCl is a strong acid and the H^+ will be 5.00E-2 for the HCl. HCN is a weak acid. Calculate the H^+ contribution from that(decreased by the HCl as a common ion), then add the two together. Total H^+ = H^+ from HCl + H^+ from HCN. Convert to pH.
July 5, 2016

chemistry
This is done the same way you worked the NH3 gas and HCl gas problem above.
July 5, 2016

AP Chemistry
dG is negative. The reaction is spontaneous. dG = -; rxn spontaneous dG = 0; rxn about 50/50 dG = +; rxn not spontaneous in the direction shown but is spontaneous for the reverse rxn.
July 5, 2016

Chemistry
heat lost by metal + heat gained by ice = 0 [mass metal x sp.h. x (Tfinal-Tinitial)] + [mass ice x heat fusiion)] = 0 25*X*(0-150) + (9g*333.5 J/g) = 0 Solve for X
July 5, 2016

chemistry
A halogen is an element, as in F2, Cl2, Br2, I2. A halide is a salt of the halogen; i.e., a compound of a metal + halide. For example, Cl2, a halogen, combines with Na(a metal) to form NaCl (a halide--more specifically it is a sodium halide. In like manner you could have KCl, ...
July 5, 2016

chemistry
MgSO4 + H2O ==> Mg^2+(aq) + SO4^2-(aq)
July 4, 2016

chemstry
(huh)^2
July 4, 2016

Chemistry
There are two atoms/unit cell in a bcc and a mole of atoms is 6.02E32 atoms. You make the conversion from atoms to mols.
July 3, 2016

chemistry
How many moles do you need? That's mols = M x L = 0.37M x 0.300 L = ? Then mols = grams/molar mass. YOu know mols and molar mass, solve for grams.
July 3, 2016

Chemistry Help Please!
1. Convert 20 ug/mL to g/L. Take 1000 mL (= 1L) 20 ug/mL x 1000 mL = 20,000 ug in that L. How many grams is that. 20,000 ug x (1 g/1E6 ug) = ? grams. mols = grams/molar mass and M = mol/L. 2. mL1 x M1 = mL2 x M2 30 x 0.03 = mL2 x 0.1M Solve for mL2. That's the mL of the ...
July 3, 2016

chemistry
mols PO4^3- ion = grams/molar mass = 9.5/approx 95 = approx 0.1 but you need to confirm all of that. There are 6.02E23 PO4^3- ions in 1 mol; therefore, there are 6.02E22 mols in the 9.5 g. In 1 PO4^3- there are 31 electrons in the P atom and 4*8 = 32 electrons in the 4 O atoms...
July 3, 2016

Chemistry
mols Al2(SO4)3 = grams/molar mass = ? Then M = mols/L solution. Then N = 6M
July 2, 2016

Chemistry
I wonder if you mean 0.0200 m or 0.002 M? Do you know there is a difference? I will assume you mean M. ..CH3NH2 + HOH --> CH3NH3^+ + OH^- I..0.02.............0..........0 C...-x..............x..........x E..0.02-x...........x..........x Kb = (CH3NH3^+)(OH^-)/(CH3NH2) ...
July 2, 2016

chemistry
It might be best for whom? to give you the answer. We're trying to help you understand the problem. We aren't too interested in giving you the answer. You have a strong acid (HCl) and a very weak acid (HCN). Usually the strong acid predominates and the pH is determined...
July 2, 2016

chemistry
HCl + NH3 ==> NH4Cl mmols HCl = 5 mmols NH3 = 5 So you have a solution of 5 mmols NH4Cl iin 75 mL and M = mmols/mL = 5/75 = 0.0667. The pH of the salt is determined by the hydrolysis of the NH4^+ .....NH4^+ + H2O ==> H3O^+ + NH3 I...0.0667............0.......0 C....-x...
July 2, 2016

chemistry
Moles are what reacts in chemistry. mols = molarity x liters. I prefer to work in millimols so mmols HCl = mL x M = ? The problems tells you M HCl is 0.3 and the mL = 300 so 300 x 0.3 = 90 mmols. Yes, you can use an ICE table and I used an abbreviated one but here is the full ...
July 2, 2016

chemistry
pH = -log (H^+) = -log(HCl) .......HCl + NaOH ==> NaCl + H2O millimols HCl = mL x M = approx 90 mmols NaOH = 50 Excess HCl = 90-50= 40 total volume = 400 mL M = mmols/mL = 40/400 = 0.1 pH = -log(H^+) = ?
July 2, 2016

chemistry
CH3COOH = HAc. Calculate M of the solutions. millimols of each. mmols = mL x M = 100 mL x 10^-3 = 0.1 mmols = 50 x 10^-2 = 0.5 Total = 0.6 M = mmols/mL = 0.6/150 mL = approx 0.004 .....Ac^- + HOH --> HAc + OH^- I...0.004............0.....0 C....-x..............x.....x E..0....
July 2, 2016

Physics/Chem
volume Al or Cu cube = 24 x 24 x 24 = ?cc. mass Al = volume x density = ? mass Cu = volume x density = ? Look up specific heat Al Look up specific heat Cu Energy removed from Al + energy added to Cu = 0 [mass Al x specific heat Al x (Tfinal-Tinitial)] + [mass Cu x specific ...
July 1, 2016

Physics/Chem
This is worked almost the same as the Al/Cu problem above. heat lost by ceramic on cooling is q = mass ceramic x specific heat ceramic x (Tfinal-Tinitial) Then look up heat vaporization liquid nitrogen. joules lost by ceramic = mass N2 x heat vaporization liquid N2. Solve for ...
July 1, 2016

chemistry
I think B<Be<F<K<Rb Look at www.webelements
July 1, 2016

Chemistry
Ni3(PO4)2is insoluble in water solution.
July 1, 2016

Chemistry
Nope. Note correct. The atoms don't balance (4Ce on right and 3 on left as well as 1 S on left and 2 on right) and charges don't balance (10+ on left and 12+ on right). 2Ce^4+ + S^2- ==> 2Ce^3+ + S
July 1, 2016

chemistry
rate 1 = H2 = 60/10 = ? rate 2 = G = 60/37.4 = ? (rate1/rate2) = sqrt(MMG/MMH2) where MMG is molar mass G and MMH2 = molar mass H2. You know molar mass H2. The only unknown is MMG.
June 30, 2016

Chemistry
right. Go the head of the class.
June 30, 2016

Chemistry
http://www.jiskha.com/display.cgi?id=1467126046
June 30, 2016

Chemistry
no way. What are you trying to do? Do you have a density problem?
June 30, 2016

Chemistry
looks good to me.
June 30, 2016

chemistry
You have written the complete ionic equation. To turn this into the net ionic equation just do this. Cancel the ions that appear on both sides. What's left is the net ionic equation. 2Na^+ are on both sides. Cancel. 2NO3^- are on both sides. Cancel. Zn^2+(aq) + 2OH^-(aq...
June 29, 2016

Chemistry
Call ascorbic acid H2A to save typing. First determine the molarity of the NaOH from pH = 14.436. pH = 14.436 so pOH = -0.436. Use pOH = -log(OH^-) and I get OH^- = 2.7 but you need to get a more accurate number and redo the rest of the problem since my work is just an ...
June 29, 2016

chemistry
Use a liquid indicator or feel it. Bases are slippery to the touch.
June 29, 2016

Chemistry
Run a % Cl test, convert to NaCl and compare the mass of the sample with that found in the test.
June 29, 2016

University of Liberia Chemistry 102
You can't plate CuSO4. You can plat Cu metal.
June 29, 2016

Chem
You can look these conversion factors up in tables or on Google. There are 3.785 L/gallon and 1.609 km/mile. So 10.6 km/L x (3.785 L/gallon) x (1 mile/km) = ? Note that you makes these conversions so the unit you have gets canceled and leaves the units you want to keep. You ...
June 28, 2016

Chem
I'm trying to help. That doesn't help me help you. If you tell me where you have trouble I will know where to start.
June 28, 2016

Chem
This looks like a lot of arithmetic. What is it you don't understand?
June 28, 2016

chemistry
% w/w = (g solute/gm soln)*100 = ? (5g/x)*100 = 16.2 x = (500/16.2) = approx 30.9 g solution. g urea + g H2O = 30.9 total. Calculate g H2O to add.
June 28, 2016

Chemistry
So x is 2.
June 28, 2016

Chemistry
http://www.jiskha.com/display.cgi?id=1467098349
June 28, 2016

Biochemistry
You need to know what "this formic acid-sodium formate solution" is.
June 27, 2016

Chemistry
To prepare 10 L of WHAT?
June 27, 2016

chemistry
CH3COOH - acetic acid = HAc CH3COONa = sodium acetate = NaAc BEFORE: you have a 200 mL of 0.1M HAc. The pH is determined by the ionization of the HAc. .........HAc ==> H^+ + Ac^- I........0.1.....0......0 C.......-x.......x......x E.......0.1-x....x......x Substitute the E ...
June 27, 2016

chemistry
OK. So we go with the 0.01 in the initial ICE chart as correct. You have 100 mL of 0.082 M. You want 2 mL of 10 mM (0.01 M) The dilution formula is mL1 x M1 = mL2 x M2 mL x 0.082 = 2 mL x 0.01M mL of 0.082M needed= 2*0.01/0.082 = 0.244 mL.
June 27, 2016

chemistry
I'm confused, too. You show 1M, 100 mL but you then have L x M = (0.1L x 0.1M). So do you mean 100 mL of 1 M or 100 mL of 0.1M? Near the end you have 0.0082 mols/0.1L and that is 0.082 and not 0.82.
June 27, 2016

Organic Chemistry
% aspirin = (0.082/5.00)*100 = ? %caffeine = )0.21/5.00)*100 = ?d etc for acetanilide. For #2, convert grams given in the problem to mols. mol = grams/molar mass = ? Then mol% aspirin = (mols aspirin/0.600)*100 = ? etc. for the others.
June 27, 2016

chemistry
We can't write Lewis dot structures on this forum. Google Lewis dot structure of each of these and you can see how they look.
June 27, 2016

Chemistry
If what you have is a pure compound and not a mixture, yes.
June 27, 2016

Chemistry
20 gm of what?
June 27, 2016

Chemistry
That's why you've been stuck on this question for hours. There isn't enough information. You MUST know how much Na2SO4 there is. This is just like asking "You're driving your car to the supermarket that's down the road 5 miles. How long will it take ...
June 26, 2016

Chemistry
Na2SO4 + BaCl2 ==> BaSO4 + 2NaCl So how much Na2SO4 do you have?
June 26, 2016

chemistry
The s orbital is not degenerate. The p orbital is with pz, px, py orbitals. The d orbital is with 5 orbitals. You can google and get the shapes of the five.
June 26, 2016

Chemistry
If you knew the answer why did you post the question?
June 26, 2016

chemistry
You are correct that both ii and iii are incorrect and for the reason you cite. i is correct. If n = 4, l can be 0,1,2,or 3; ml can be -3.-2,-1,0,1,2,3; ms can be +/- 1/2. Note: for iii, I think you meant to write "l can be 0,1,2,3 or 4." t-4 doesn't make sense ...
June 26, 2016

chemistry
It's a statement about the Heisenberg Uncertainty Principle. That says that if you can know exactly where the electron is sitting, you can not know its velocity. The reverse is true, also. If you know how fast it is traveling, you can not at any instant exactly where it is...
June 26, 2016

chemestry
A quadratic is not required and you can let 0.0667-x = 0.0667.
June 26, 2016

chemestry
First, please spell chemistry right. I'm annoyed. Second, this is a buffer problem for the first addition. They throw you a curve with the second addition because it is NOT a second buffer problem. Here is the scoop. Call acetic acid, CH3COOH, as HAc. millimols HAc = mL x ...
June 26, 2016

Chemistry
Look up the delta Hof values for each, then dHrxn = (n*dHf products) - (n*dHf reactants). This dHrxn will be for 34 g NH3. For 2.5 g it will be dHrxn x (2/34) = ?
June 26, 2016

chemestry
I ASSUME this is a beginning class and they expect you to view H2SO4 as a dibasic acid; i.e., 0.05M x 2 = 0.1M in (H^+). Actually, that isn't right as (H^+) really is closer to o.059M and not 0.1. But we will go with the assumption. Let's call formic acid as HFm to ...
June 25, 2016

CHEMISTRY
If you understand the post below you will know how to do this. I'll check your answers.
June 24, 2016

CHEMISTRY
But you know those answers are wrong. You should follow my rules above to get the correct answers.
June 24, 2016

CHEMISTRY
Here is how you do a couple of them. Then you try the others. Sr and NO3^-1 Sr is a +2 charge. There is no Sr with a +3 charge. Sr(NO3)2. You can see Sr is +2 and 2 NO3^- is -2 so the +2 neutralizes the -2. All compounds will be zero charge and that's how you know what ...
June 24, 2016

Chemistry
Those don't react but if they did it would be this. 2FePO4 + 3Na2SO4 ==> 2Na3PO4 + Fe2(SO4)3 mols FePO4 = grams/molar mass = ? Then using the coefficients in the balanced equation, convert mols FePO4 to mols Fe2(SO4)3. That's mols FePO4 x (1 mol Fe2(SO4)3/2 mols ...
June 24, 2016

CHEMISTRY
I'm sure you mean [NO3]^-, [SO4]^2- etc. Then In(NO3)3, In2(SO4)3, etc. If we could write subscripts very well on this forum the nitrate would be [NO3]-
June 24, 2016

CHEMISTRY
See your other post.
June 24, 2016

Science-chemistry
If %A = 22.22%, then %B = 77.78. Take 100 g sample to give you 22.22 g A 77.78 g B. Convert to mols. 22.22/40 = 0.5555 mols A. 77.78/atomic mass B = ? mols B. You know the ratio is A2B5; re-write this way letting X stand for atomic mass of B. 22.22/40 = 0.5555 x some # = 2 77....
June 24, 2016

chemistry
How many mols do you need? That's M x L = ? mols NaOH. Then grams = mols NaOH x molar mass NaOH
June 23, 2016

chemistry
........BaCrO4 ==> Ba^2+ + CrO4^2- I.......solid.......0.......0 C.......solid.......x.......x E.......solid.......x.......x Substitute the E line into Ksp expression and solve for x = solubility
June 23, 2016

another approach---Chemistry
Calculate % each element. %X = (0.36/0.56)*100 = 64.3% %O = (0.2/0.56)*100 = 35.7% Take 100 g sample to give 64.3 g X 35.7 g O Convert to mols. 64.3/at mass X = ?mols X. 35.7/16 = 2.23 mols O. We know this is in the ratio of 2:3 so, letting X = atomic mass X 64.3/X = ?......*...
June 23, 2016

Chemistry
Use PV = nRT and solve for n. Look up the vapor pressure of H2O at 20 C. It is approximately 20 torr BUT that's just a guess (although a very close guess). Ptotal = pH2O + pAr You know ptotal and pH2O, solve for pAr and use that for P in PV = nRT. Substitute the other ...
June 22, 2016

Chemistry
1 carat = 0.2 g; therefore, 15 carats = 3 g. Then mol = grams/molar mass = ? That gives you mols in the mineral. Since there are 3 mols of Si in 1 mole of the mineral, mols Si will be 3x mols in the mineral.
June 22, 2016

  1. Pages:
  2. <<Prev
  3. 1
  4. 2
  5. 3
  6. 4
  7. 5
  8. 6
  9. 7
  10. 8
  11. 9
  12. 10
  13. 11
  14. 12
  15. 13
  16. 14
  17. 15
  18. Next>>