Sunday
September 25, 2016

Posts by DrBob222

Total # Posts: 53,132

Chemistry
I agree with Bob P but your answer, with that many significant figures, could be counted wrong. b. is right. Same comment about s.f.
September 15, 2016

Chemistry G.12
I agree with you for a. It TAKES energy to break the crystal lattice. Heat is given off when hydrates are formed. b. I also agree with hydration energy for b. If more energy is given off in forming a hydrate that should increase the solubility.
September 15, 2016

Chemistry
Since the density is 1.00 g/mL, that makes the mass of solution the same as the volume of the solution. My old standby is to know that 1 ppm = 1 mg/L. 13.7 g pesticide = 13.7 x 1000/250 = approx 55 mg/L = approx 55 ppm. That is the same as approx 55,000 ppb.
September 15, 2016

CHEMISTRY
MnO4^- + 8H^+ +5e = Mn^2+ + 4H2O 2CHCl3 + 4H2O==> 3Cl2 + 2CO2 + 10 H^+ + 10e Multiply equation 1 by 10; equation 2 by 1 and add,
September 15, 2016

Chemistry
See your other post.
September 15, 2016

ap chemistry
It helps us help you if you pick a name, as writeacher suggests, and stick with it. B is not true. All of the others are ok
September 15, 2016

ap chemistry
K = (products)/(reactants) Let's just say P = 1 and R = 1, then K = 1/1 = 1 and Q = K Now let's change the P and R to say P = 2, then Q = 2/1 so Q>K and P is higher; R is smaller. If P<1, then Q<K and R is higher; P is smaller. Pick the right answer from this...
September 15, 2016

chemistry -3.2.4
I answered this for you yesterday.
September 15, 2016

chemistry - 3.1.6
......2HI ==> H2 + I2 I.....1.60.....0....0 C.....-2x......x....x E....1.60-2x...x....x Substitutethe E line into the Keq expression and solve for x.
September 15, 2016

Chemistry
Is that 0.2512 M stock? I will assume it is. mols NaOH = M x L = ? mols HCl = mols NaOH (since 1 mol HCl = 1 mol NaOH in the balanced equation). M HCL stock = mols/L. You know M and you know mols, solve for L and change to mL if desired.
September 15, 2016

chemistry - 4.1.4
No. (H^+)(OH^-) = Kw = 1E-14. You know OH, solve for H.
September 15, 2016

chemistry
NaOH is a strong base.
September 15, 2016

chemistry
A is not right. K = ([products)/(reactants)
September 15, 2016

Chem
6.5g/3.0 mL = ?
September 14, 2016

Chem
CH3COONa.3H2O ==> CH3COO^-(aq) + Na^+(aq) + 3H2O
September 14, 2016

chemistry
You include but don't "ADD" i. For KNO3 i = 2 delta T = i*Kf*m or delta T = i*Kb*m
September 13, 2016

Chemistry
I don't get "converted to solid enthalpy"
September 13, 2016

Chemistry
So why not tell us what you did? That way we could help. This way you just want the answer.
September 13, 2016

Chemistry
mols C = 12/12 = ? mols Mg = 12/24.3 = ? 1 mol of anything contains 6.02E23 atoms.
September 13, 2016

chemistry
You can look this up on Google.
September 13, 2016

chem
w = wavelength 1/w = 1.0973E7(1/1 - 1/n^2). Convert w to meters and solve for n. That gives you n to which the electron moves from the ground state.I get n = 7 Then 1/w = 1.0973E7(1/n^2 - 1/7^2). Convert 2165 nm to m and solve for n. That looks like about 4 to me.
September 13, 2016

chemistry
I think this is a nonsense question although I suspect you have typed it as it was presented to you. I think the author of this problem probably expects you to answer that you expect more solid than the ion (based on the small number for Ksp); however, the amount of solid AgCl...
September 12, 2016

chemistry 102
You don't have enough information. I don't know what you did in the experiment.
September 12, 2016

chemistry
Not enough information to answer. You need to explain what you did.
September 12, 2016

chemistry
Finding Ka values for these salts is difficult. Intuitively I would think AlCl3 would be more acidic; however, I found Ka for FeCl3 = 2E-3 and for AlCl3 = 1.2E-5. From that information FeCl3 is the stronger. I could find no information about BeCl2 or NiCl3. Sorry I can't ...
September 12, 2016

chemistry
You started with 25g solution and recovered 4g of salt. So the solubility is 4g per 25g. That would be 4 x 100/25 = solubility in 100 g.
September 12, 2016

chemistry
what table?
September 12, 2016

chemistry
I see a lot of posts here. No indication of what you think the answer is. This is a homework help site and not a homework do site. If you have something you don't understand I shall be glad to help you through it if you explain in detail what you're having trouble with...
September 12, 2016

Chhem
the temperature of the salt water
September 11, 2016

Chemistry
1.5 + 12.0 = ?
September 11, 2016

Biochemistry
You should use k1. You are starting with NaHCO3, not Na2CO3. And (base) + (acid) = 0.5M For buffers you want to use a pKa within +/- 1 of the desired pH.
September 11, 2016

Chemistry
2Na + H2SO4 ==> Na2SO4 + H2 single displacement I'll leave the other one for you. products are Mg3(PO4)2 + H2O It is a double displacement reaction.
September 11, 2016

Chem
Ag^+(aq) + Cl^-(aq) ==> AgCl(s)
September 11, 2016

chemistry
Step 1. Write and balance the equation. Ba(OH)2 + 2HCl ==> BaCl2 + 2H2O Step 2. mols Ba(OH)2 = M x L = ? That's approx 0.0046 but you need an accurate answer. Step 3. Using the coefficients in the balanced equation, convert mols Ba(OH)2 to mols HCl. That's approx 0....
September 11, 2016

Chem
This is a double displacement (or double replacement) reaction. The Mg combines with the Cl to make MgCl2; the OH combines with the H to make H2O.
September 11, 2016

chemistry
The best answer here is A but that isn't always correct.
September 11, 2016

chemistry
Generally A but that isn't always correct.
September 11, 2016

chemistry
Technically this question can't be answered without knowing that the salts have the same ratio of cations to anions.
September 11, 2016

chemistry
Write the ionization expression for HAc. HAc ==> H^+ + AC^- now K = (H^+)(Ac^-)/(HAc) Now if NaAc is added, that increases the Ac^- (the common ion effect), that shifts the equilibrium to the left. What happens to the H^+ and how does that affect the pH. By the way, this is...
September 11, 2016

chemistry
I can write a Keq for all of them.
September 11, 2016

chemistry
A. This is the definition of equilibrium.
September 11, 2016

chemistry
A definition. We will be glad to critique your thoughts. Looking them up will help you remember; having us do them for you will not.
September 11, 2016

chemistry
C'mon. What is your problem with this? It a definition for K. You need to know the definition and you can do these yourself. Also, you need to use arrows. ==> or --> or >>>.
September 11, 2016

chemistry
K = (H2O)^2/(H2)^2(O2) In increase in P means the reaction will shift to the side with fewer mols. So increase in P shifts to the right; therefore, a decrease must shift to the left. There are two answers for left (A and D). Can you figures with Q is larger or smaller.
September 11, 2016

chemistry
Keq = (Fe^2+aq)(Cl^-aq)^2/(FeCl2). Some may argue that the denominator of FeCl2 should not appear; however, by definition it is 1 and like to put it in.
September 11, 2016

Chemistry
0.326 g = mass FeCl2.xH2O -0.254 g = mass FeCl2 -------------- 0.072 g = mass xH2O mols FeCl2 = grams/molar mass = ? mols H2O = grams/molar mass = ? Now find the ratio of 1 mol FeCl2 to H2O and round to a whole number. That whole number will be x. The easy way to do that is ...
September 11, 2016

Chemistry
delta T = Kf*molality You know delta T and Kf, solve for m. molality = mols/kg solvent. You know m and kg solvent, solve for mols. Then mols = grams/molar mass You know mols and grams, solve for molar mass.
September 11, 2016

Chemistry
All you gave was a number. I can't tell you what you're doing wrong since you didn't show your work. The right answer is in the ball park of 560 g
September 11, 2016

chemistry
mols CaCl2 = grams/molar mass. mols Cl^- = twice that since there are 2 mols Cl^- for every mols CaCl2. Then there are 6.02E23 Cl^- for every mol Cl^-.
September 11, 2016

chemistry
Here is a "balanced" equation. 2C2H2 + 5O2 ==> 4CO2 + 2H2O
September 11, 2016

Chemistry
I2 is diatomic. Zn + I2 ==> ZnI2 Use 1 mol I2 = 1 mol ZnI2. If you wanted mols I ATOMS, then 1 mol ZnI2 = 2 mol I atoms.
September 11, 2016

Science
Without knowing the initial procedure or the updated procedure, no one can help you.
September 10, 2016

Chemistry
Zn + 2HCl ==> H2 + ZnCl2 mols Zn = grams Zn/atomic mass Zn = ? Using the coefficients in the balanced equation, convert mols Zn to mols HCl. That will be mols Zn x 2 = mols HCl. Then M = mols/L. You know M of HCl, mols HCl, solve for L HCl and convert to mL
September 10, 2016

Physical Chemistry
a. [mass Au x specific heat Au x (Tfinal-Tinitial)] + [mass Ag x specific heat Ag x (Tfinal-Tintitial)] = 0 Substitute and solve for Tfinal. b. q = [mass Au x specific heat Au x (Tfinal-Tinitial)] OR q = ([mass Ag x specific heat Ag x (Tfinal-Tinitial)] q is the same for each ...
September 10, 2016

chemistry
I think you are right that OMe is a ortho/para directing group. I think the CO2R is an ester and esters are meta directing.
September 10, 2016

Chemistry
M = mols/L M = 1.5 mols/1.5 L = 1.0 M
September 10, 2016

Chemistry (equilibrium)
Since the dH reaction is +312 kJ, that means the reaction is endothermic so I would write it as C2H6 + heat = C2H2 + 2H2 So if T is decreased, rxn shift to the left. (Rxn uses heat to go to the right; take heat away it moves to the left). Add He at constant volume. If volume ...
September 10, 2016

chemistry help
Emma, you didn't like my answer? http://www.jiskha.com/display.cgi?id=1473523976
September 10, 2016

Chemistry
If it exists I would name it nitrogen trioxide.
September 10, 2016

chemistry
I don't think there is an answer. A is true most of the time but not always. It depends, somewhat, upon how acids and bases are defined. D is a true statement but that isn't neutralization. B and D are true, also, but those aren't neutralization reactions.
September 10, 2016

chemistry
I don't understand how the answer can be D. There is no water in the reaction. What you want to do is to shift the equilibrium to the left (remove the OH^-) and you can do that by adding an acid so I would choose B.
September 10, 2016

chemistry
I would go with B.
September 10, 2016

chemistry
I don't think so. H2 + O2 ==> 2H2O If P increases, it shifts to side with fewer moles of gases. There are 3 mols on the left; two moles on the right so for increase P it shifts to the right. A decrease in P must shift to the left.
September 10, 2016

chemistry
You could save a lot of time by using this: 2H2 + O2 ==> 2H2O. Everyone knows that the number two following H and O are subscripts. We CAN write them as subscripts but no one wants to take the time to do it. 2H2 + O2 ===> 2H2O Here is the rule to follow: An increase in ...
September 10, 2016

chemistry
Equilibrium is reached when the forward reaction rate equals the reverse reaction rate.
September 10, 2016

chemistry
I'm having trouble following the question. Please rephrase, don't omit words, and please no abbreviations; e.g. I have no idea what PP end point is.
September 10, 2016

Biochm I
I agree
September 10, 2016

chemistry
All are right
September 10, 2016

chemistry
EDTA complexes CaCO3. Here is explanation. http://www.austincc.edu/dsackett/CHEM1412/lab/1412exp47.pdf
September 10, 2016

Chemistry
You look at the graph and pick the midpoint (the inflection in the graph). At that point, (HA) = (A^-) and pH = pKa.
September 9, 2016

Chemistry urgent please
Sorry, I know nothing about the Japanese pharmacopeia.
September 9, 2016

Chemistry urgent please
If this is a qual test you need have enough dil HNO3 to make the solution slightly acid. Add dil HNO3 to the solution dropwise until it is acid to litmus paper. The actual amount you need to add will be determined by the amount of NaOH present in the test.
September 9, 2016

Chemistry
P*molar mass = density x RT
September 9, 2016

Science
Are these three question? What do you want? Are these multiple choice?
September 9, 2016

Chemistry(please check my answer)
right
September 9, 2016

chemistry
CH4 + 2O2 ==> CO2 + 2H2O mols CH4 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols CH4 to mols CO2, then again convert mols CH4 to mols H2O. Then convert mols CO2 and mols H2O to grams of each. g CO2 = mols CO2 x molar mass CO2 g H2O = ...
September 9, 2016

chem help!
Reactions with dG negative are spontaneous.
September 9, 2016

chem help!
dG = -RTlnK If dG is - then K is + and a +K means products are greater than reactants. Products are in the numerator; reactants in the denominator.
September 9, 2016

Chemistry
No details. Can't answer.
September 9, 2016

Chemistry
Note the correct spelling of Celsius. Probably something is missing. With no volume CO listed you can't give a volume of O2 required. However, with no volume CO listed, you could answer that the required amount of O2 required is 1/2 the volume of CO used.
September 9, 2016

chemistry
I read all of these posts. Almost all are solved with the Henderson-Hasselbalch equation, or some variation of the HH equation. I think all of them are buffer problems. I suggest you pick one of them; e.g. the carbonate/bicarbonate problem, show what you have done or what you ...
September 9, 2016

chem
pH> = basic pH<7 = acid pH=7 = neutral
September 8, 2016

chem
I don't like any of the answers but if I had to pick one I would chose A.
September 8, 2016

chem
I don't agree with you. C and D are smaller numbes than A or B
September 8, 2016

chem
http://www.chem.purdue.edu/gchelp/howtosolveit/Kinetics/IntegratedRateLaws.html
September 8, 2016

chem
http://bouman.chem.georgetown.edu/S02/lect4/lect4.htm
September 8, 2016

chem
https://en.wikipedia.org/wiki/Four-stroke_engine
September 8, 2016

Chemistry
https://en.wikipedia.org/wiki/Oncotic_pressure
September 8, 2016

chemistry
rate = k(NO)(O3) rate = 1.5E7(NO)(O3)
September 8, 2016

chemistry
See your other post. Please use the same screen name.
September 8, 2016

chemistry
I believe you need to read and correct the question. Also let me point out that nacl and h2so4 don't mean anything to me. Find the caps key and use it.
September 8, 2016

Chemistry
Frankly I don't understand your question. You're right. Both Cu(OH)2 and BaSO4 are solids and you have labeled them correctly. According to the solubility rules, a reaction proceeds when ONE of the products is a solid. This doesn't change when BOTH products are ...
September 8, 2016

Chemistry
double post.
September 8, 2016

AP Chemistry
3F2 + Cl2 ==> 2ClF3 mols F2 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols F2 to mols ClF3. That will be mols F2 x (2/3) = ? Then convert mols ClF3 to grams. g = mols x molar mass = ? This is the theoretical yield (TY). You know from ...
September 7, 2016

Chemistry
yes
September 7, 2016

Chemistry
I'm having trouble with understanding this problem because Ag2CO3 is more soluble than AgI
September 7, 2016

Chemistry
Too little CO2 means too little NaHCO3.
September 7, 2016

Chemistry
It should be obvious that if some CO2 leaks out the amount of CO2 measured will be less so it will be understated. What is it about this problem you don't understand.
September 7, 2016

Chemistry
I'm sorry but my crystal isn't working tonight. If you told me what you did and what you observed I could help.
September 7, 2016

Chemistry
mols = grams/molar mass = ?
September 7, 2016

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