Tuesday
September 1, 2015

Posts by DrBob222


Total # Posts: 49,862

Chemistry
Assuming you meant 0.2 M and not 0.2 m, then HNO3 + OH^- ==> NO3^- + H2O mols HNO3 = M x L = 0.02 x 0.2 = 0.004 mols OH- = the same since 1 mol HNO3 reacts with 1 mol OH-. Then M OH- = mols OH-/L OH- = 0.004/0.04 = 0.1 M. Now let's be careful here. That 0.1M is the (OH...
May 28, 2015

chemistry
Use (P1V1/T1) = (P2V2/T2) For P1 use 750-14 = ? V1 = 50 cc T1 = 273+17 = ? P2 and T2 ae STP V2 = solve for this in cc.
May 28, 2015

Chemistry
PV = nRT and solve for n = number of mols. Then n = grams/molar mass. You know molar mass and n, solve for grams.
May 28, 2015

Chemistry
Is that 60 g? q = mass NH3 x heat vaporization NH3
May 28, 2015

chemistry
I don't understand the question. Do you mean 0.3 cc LiOH neutralizes 0.2 M H2SO4. How much H2SO4 was neutralized?
May 28, 2015

Chemistry
PV = nRT Remember T must be in kelvin. n = grams/molar mass He = 27800g/molar mass He.
May 27, 2015

Chemistry
See your post above. Same PV = nRT
May 27, 2015

Chemistry
M x L x molar mass = grams.
May 27, 2015

Chemistry
mols Na2CO3 = M x L = ? mols Na^+ = twice that since there are two Na ions in 1 molecule of Na2CO3. mols NaHCO3 = M x L = ? Total Na = mols Na from Na2CO3 + mols Na from NaHCO3. M Na = mols Na/total volume in L
May 27, 2015

Chemistry
CH3COOH + NaOH --> CH3COONa + H2O millimols CH3COOH = 50 x 0.150 = ? millimols NaOH = 49 x 0.150 = ? mmols CH3COOH left = the difference. M CH3COOH = mmols/total mL = ? Then convert to pH.
May 27, 2015

chemistry
What is ,300m7^3?
May 27, 2015

Chemistry
2.5L is right for a. I don't agree with 3.00 L for b. What you want is ?Lair x 0.2 oxygen = 2.5 L oxygen. ?Lair = 2.5 Loxygen/0.2 oxygen = ? which I think is 12.5 L air. Check it. 12.5 L air x 0.2 oxygen = 2.5 L oxygen. Do c the same way.
May 27, 2015

chemistry- titration
I don't understand what you've done but the HH equation should be pH = pKa + log (base)/(acid). After you know the Ka value, assuming it is monoprotic, then mLacid x Macid = mLbase x Mbase
May 27, 2015

chemistry
First you need to correct the typos and make sue you have the correct numbers. They can't be right because they don't add to 100%
May 27, 2015

chemistry
I don't see a question. If you want an answer you should explain what you hav written.
May 27, 2015

Chemistry
dG = -nFEo
May 27, 2015

chemistry
First step. Cu2S ==> 2CuO Cu changes from total of +2 on the left to total of +4 on the right. S changes from +6 in SO4^2- to +4 in SO2. Now you balance the two half reactions.
May 27, 2015

science
1. (1/16)*6.02E23 = ? 2. (1/32)*6.o2E23*(2 atoms O/molecule O2) = ? 3. (1/48)*6.02E23*(3 atoms o/molecule O3) = ?
May 27, 2015

college chemistry
q1 = heat needed to change phase of ice from solid to liquid(i.e., to melt ice)? q1 = mass ice x heat fusioin q2 = heat needed to raise T of liquid water from zero C to 100 C. q2 = mass H2O x specific heat H2O x (Tfinal-Tinitial) q3 = heat needed to change phase of liquid ...
May 26, 2015

Chemistry
Without Figure 13.7 how am I supposed to help you? In the absence of Figure 13.7, you can use the Clausius Clapeyron equation of ln(P2/P1) = (dHvap/R)(1/T1 - 1/T2) P2 is 330 P1 is 760 dHvap is whatever in jouls/mol R is 8.314 T1 is 100C (remember that's 373 K) T2 is ? and ...
May 26, 2015

Chemistry
From your previous post. q1 to melt ice + q2 to heat melted ice to final T + q3 to cool 90 C water to final T = 0 q1 to melt ice is that mass ice x heat fusion. (That change the phase) q2 to raise T of melted ice is that mass H2O x specific heat H2O x (Tfinal-Tinitial). (That ...
May 26, 2015

Chemistry
Look at your ice to steam problem above. This is the same concept. After you have one of these worked you should be able to follow the template and work the others. In these problems there are two formulas. 1. When changing T WITHIN A PHASE (i.e., one T in ice to another T in ...
May 26, 2015

Chemistry
I showed you how to do this yesterday. Why are you posting again?
May 26, 2015

Chemistry
C2H4 + 3O2 ==> 2CO2 + 2H2O 10.0 what? Change 10? to mols if it isn't already in mols. dH = 1410 kJ/mol x (# mols) = ?
May 26, 2015

CHEMISTRY
Use the Henderson-Hasselbalch equation. KH2PO4 is the acid and K2HPO4 is the base.
May 26, 2015

chemistry
Do you know the solubility of I2? Do you have an equilibrium constant. A distribution constant? Any other information available. I just don't have thousands (millions?) of solubility data memorized. No one does.
May 26, 2015

Chemistry
a. 134 g MgSO4.7H2O x (7*molar mass H2O/molar mass MgSO4.7H2O) b. 134 g MgSO4.7H2O x (molar mass MgSO4/molar mass MgSO4.7H2O) = ?
May 26, 2015

chemistry
a. q = mass Al x specific heat Al x (Tfinal-Tinitial) b. Look at your specific heat problem just before this as a hint (if you need a hint).
May 26, 2015

chemistry
heat lost by metal + heat gained by water = 0 [mass metal x specific heat metal x (Tfinal-Tinitial)] + [mass H2O x specific heat H2O x (Tfinal-Tinitial)] = 0 Substitute and solve for the only unknown in the set up.
May 26, 2015

chemistry
q1 = heat needed to raise T of ice from -22 to zero C. q1 = mass ice x specific heat ice x (Tfinal-Tinitial) q2 = heat needed to change solid ice at zero C to liquid H2O at zero C. q2 = mass ice x heat fusion q3 = heat needed to raise T of liquid water from zero C to 22.0 C. ...
May 26, 2015

chemistry
Three hints. 1. You need to find the caps key and use it. 2. You need to use proper sentence structure so we know when one sentence ends and the next one starts. 3. You need to rewrite this question and rephrase it so it makes sense. As is it makes no sense whatsoever.
May 26, 2015

Chemistry
Look up the Ka for HF and compare it with the Ka for acetic acid. Use 0.1M for the two solution and calculate the (H^+) and the pH. You will see the difference.
May 26, 2015

Chemistry
q = mass solution x specific heat solution x (Tfinal-Tinitial) mass solution = 75 + 75 = 150 mL and that is 150 g since density is 1.00 g/mL. You have the specific heat and Tfinal andTinitial. Calculate q. Then delta E = q + w You have q from above. I believe w is zero. It is ...
May 26, 2015

Chemistry
Convert 6.6g NaOCl to mols. mols = grams/molar mass. Then M = mols/L solution
May 25, 2015

chemistry
The is a limiting reagent (LR) problem and you know that because amounts are given for BOTH reactants. 1. Write and balance the reaction. The products are CO2 and H2O. 2. Convert grams C6H6 (use caps) to mols. mols = grams/molar mass 3. Do the same and convert g O2 to mols. 4...
May 25, 2015

Chemistry check my answers
1. Synthesis is right. You should note the color of the oxide produced. A red or yellow color denotes the formaton of Cu2O. A black color is CuO. Generally if Cu is heated in air it forms both. 4. There is nothing wrong with what you wrote; however, I wanted you to know that ...
May 25, 2015

Chemistry check
No
May 25, 2015

Chemistry
1. Convert 73.1 g CsXeF7 to mols. mols = grams/molar mass = ? 2. Using the coefficients in the balanced equation, convert mols CsXeF7 to mols CsF. 3. Now convert mols CsF to grams. g = mols x molar mass.
May 25, 2015

ap chemistry
Ecell = Eocell - (0.05916/n)*log Q You have Ecell and Eocell. n is 2 and Q = (Fe^2+)^3/(Fe^3+)^2 Substitute and solve for (Fe^2+). 0.047M is the correct answer.
May 25, 2015

Chemistry
mL1 x M1 = mL2 x M2
May 25, 2015

science
The half life of insulin is prolonged due to less degradation. http://clinical.diabetesjournals.org/content/25/3/90.full
May 25, 2015

chemistry
How many mols NO3^- do you want. That's M x L = mols = 0.25 x 0.5L = 0.125 How many mols do you have in the NaNO3? That's mols = grams/molar mass = 5.0/85 = approx 0.06 but you need a more accurate answer that the estimate. How many more mols do you need to be ...
May 25, 2015

chemistry
15 g Ca(OH)2 = ? mols. That's 15/molar mass Ca(OH)2 = 15/74 = estimated 0.2 You used how many mols for the neutralization? That's 0.2 x (300/500) = estimated 0.12 mol Ca(OH)2. The equation is Ca(OH)2 + 2HCl ==> CaCl2 + 2H2O If you neutralize 0.12 mols Ca(OH)2 it ...
May 25, 2015

chemistry
How about this? volume of Hg is mass/density or in dimensional analysis it is 20g x (1 cc/13.6 g) (g cancels and leaves cc which is volume) of Hg. . Now we want to convert to grams alcohol. 20 g x (1 cc/13.6 g) x (0.9 g/cc) = ? cc on top cancels with cc on bottom. g on top ...
May 25, 2015

Chemistry
Substitute into the HH equation. HF is the acid; NaF is the base.
May 25, 2015

Chemistry
That's right. Think what temperature H2O condenses from gas to liquid (or freezes to a solid) vs temperature CO2 condenses from gas to solid.
May 25, 2015

chemisrty
I don't know where you have it but the sum of the partial pressure of each is the total pressure. 1.5 + 1.6 + 1.3 = ? atm. You have a tough time getting 1.3 atm H2O vapor unless the container is sealed since the vapor pressure at boiling point is 1 atm.
May 24, 2015

Chemistry
How can we help you with this assignment short of writing out a textbook procedure for you? I'll be glad to answer any questions or critique what you write.
May 24, 2015

Chemistry
2KOH + H2SO4 ==> K2SO4 + 2H2O mols KOH = M x L = ? mols H2SO4 = 1/2 that looking at the coefficients in the balanced equation. Then M H2SO4 = mols H2SO4/L H2SO4. You know mols and M, solve for L.
May 24, 2015

CHEM
q = mass H2O x specific heat H2O x (Tfinal-Tinitial) You know q, mass H2O, specific heat and Tfinal. Solve for Tinitial.
May 24, 2015

chemistry
You must know how to do parts of this. What about the problem do you not understand? a. m = mols/kg solvent. You have volume and density. That's how you determine kg solvent. b. XNaCl = n/total mols XH2O - n/total mols c. % NaCl w/w = grams NaCl/100 g solution. d. Take the...
May 24, 2015

chemistry
See your other post.
May 24, 2015

ap chem
96,485 Coulombs can plate out approx 209/3 grams Bi. You need a better answer than that estimate. How many coulombs do you have? That's C = amperes x seconds = approx 5.60 x 23.8 x 60 s/min = ? 209/3 x ?coulombs/96,485 = g plated out.
May 22, 2015

AP Chem ---
k = 0.693/t1/2 Solve for k and substitute into the below. ln(No/N) = kt No = 100 N = 25 k from above Solve for t in days.
May 22, 2015

AP Chem ---
See your post above.
May 22, 2015

AP Chem ---
zXw ==> 11Na24 + 2He4 z = 11 + 2 = ? (13 and that is Al) w = 24 + 4 = ? So the equation is 13Al28 ==> 11Na24 + 2He4
May 22, 2015

Chemistry
24Cr51 ==> 25Mn51 + -1eo So that must be a beta decay.
May 22, 2015

Chemistry
Pb is +2 on the left and +2 on the right O is zero on the left and -2 on the right. S is -2 on the left and +4 on the right.
May 22, 2015

Chemistry
Oxidation is the loss of electrons. Cu is +2 on the left and zero on the right. H2 is zero on the left and +1 on the right.
May 22, 2015

is the ph= o for the H+
10^-0.249 = 0.56 so from these numbers the pH = 0.56.
May 21, 2015

is the ph= o for the H+
If you will show your work I can check it.
May 21, 2015

CHEMISTRY ( I NEED HELP AGAIN QUICK )
The first question is a limiting reagent problem. You work it the same way as the previous LR problem. The second one is not a LR problem but a simple stoichiometry problem. So instead of converting two reactants to mols of product and choosing which one to use you have only ...
May 21, 2015

chem 100
a. .........PbI2 ==> Pb^2+ + 2I^- I........solid.....0.......0 C.........-x.......x.......2x E........solid.....x.......2x Sustitute the E line into Ksp expression and solve for x = (Pb^2+) b. You need Kc for the reaction and you can get that from the sum of the two ...
May 21, 2015

Chem 100
http://www.chemistry.wustl.edu/~edudev/LabTutorials/naming_coord_comp.html
May 21, 2015

Chemistry (I NEED HELP REAL QUICK)
This is a limiting reagent (LR) problem and you know that because amounts for BOTH reactants are given. I work these the long way. BaCl2 + MgSO4 ==> MgCl2 + BaSO4 mols BaCl2 = M x L = ? mols MgSO4 = M x L = ? Use the coefficients in the balanced equation to convert mols ...
May 21, 2015

chem
You don't have a workable equation.
May 21, 2015

Chemistry
NF3 is trigonal pyramidal; therefore, it is not symmetrical in three dimensions. NF4^+ is tetrahedral and is not polar because the N-F polar bonds balance each other. That is not true for NF3.
May 21, 2015

science
I would choose a,b,d with a note that heat energy is the only end product of the transfer. The others are USING electrical energy to make the transfer from an electromagnetic wave in space that contains the video and audio signals into light and sound.
May 21, 2015

science
I don't think much of this question. It's worse than the one above it. The answer is it depends upon where you place it. If you place it on the stove top burner it is mostly conduction. If you place it in the oven it is mostly convection but with some radiation.
May 21, 2015

Chemistry
It takes 96,485 coulombs to deposit 65.4g/2 = estimated 33 g Zn You want 81.5 g so that will require how many coulombs? That's 96,485 x (81.5/33) = ? C. Then C = amperes x seconds. You know C and amperes, solve for seconds. Remember that 33 g is an estimate so you need to ...
May 21, 2015

Chemistry
The Al is not right. Al atoms balance. H atoms balance O atoms balance. Charge does not balance. You have 6- on the left and zero on the right. You can fix that by placing the 3e on the right. The CrO4^2- half reaction is balanced. The total equation is not balanced. Al is ok ...
May 21, 2015

Chemistry
H2 gas is released. You can test it by collected some of the gas in a test tube (it is lighter than air so it floats UP) and hold a lighted match at the mouth of the test tube. A slight explosion shows the presence of H2 gas. Zn + 2HCl ==> H2 + ZnCl2.
May 20, 2015

college chemistry
You have some number = (H^+)^14 You can do it two ways. The easier way I think is to key in the number, punch the x^y button on your calculator, and key in 0.07142 (that's 1/14), then hit the enter or = button depending upon how you get the answer out of the calculator. ...
May 20, 2015

college chemistry
You fill in all of those numbers. (H^+) is the only unknown in the entire equation (I know I said calculate Q but of course you can't do that). After you've solve for H^+ you convert to pH. The easy way to do that is to start out with Ecell = EoCell - 0.05916/n)*log Q ...
May 20, 2015

college chemistry
Ecell = EoCell - 0.05916/n)*log Q Ecell is given. Calculate Eocell the usual way n = 6 Q = (Al^3+)^2(Cr^3+)^2/(Cr2O7^2-)(H^+)^14 and you plug in the concentrations given in the problem to find Q.
May 20, 2015

college chemistry
You need to look up the reduction potentials and explain what you don't understand. Do you know what an oxidizing agent is? reducing agent?
May 20, 2015

ap chemistry
Refer to the problem just below that I worked for you (the Cu one).
May 20, 2015

college chemistry
Look up the reduction potentials. The most positive reactions is #1.
May 20, 2015

college chemistry
Coulombs = amperes x seconds = ? Let's estimate that at 3000 C. We know 63.54/2 = estimated 32 grams Cu will be deposited by 96,485 C. Therefore you will have deposited 32 x 3000/96,485 = ?
May 20, 2015

college chemistry
I don't know what you're asking. For b, you want to know anode and cathode for which reaction? The spontaneous or non-spontaneous cell. For the cell given, look up each half reaction and calculate the Ecell. If it is +, the reaction proceeds as written and the anode is...
May 20, 2015

Chemistry
Write and balance the three steps as equations. Convert 118 kg isobutylbenzene to mols. mols = grams/molar mass = ? Use the coefficients in the balanced equation to convert mols isobutylbenzene to mols ibuprofen. Multiply by 0.24, then convert mols of product to grams. g = ...
May 20, 2015

Chemistry
Rf value = (distance by unknown/distance by solvent) Substitute and solve for distance by the 0.81 material and the 0.21 material, then subtract one from the other to find the distance between them.
May 20, 2015

chemistry
What kind of a course is this? What are your information sources? text, notes, internet, other? I'm asking these questions because I don't understand why these answers don't stand out in your resource material.
May 20, 2015

Chemistry
0 = qcal + qcombustion 0 = Ccal*(delta T) + qcombustion 0 = 7854*delta T + qcomb Solve for qcomb Then q/mol = (qabove/1.76)*molar mass quinone
May 20, 2015

chemistry
Another. You didn't tell us how much metal(III) chloride OR how much HgI2 was formed. We beed one of them.
May 20, 2015

chemistry
The lower case i is not correct. It should be, for example, mercury(II) chloride. What does metal(iii) mean? Is that an M^3+ ion. And where does the I of HgI2 come from? I think your post needs editing and re-posting.
May 20, 2015

cell notation
What you have is ok under most circumstances. The molarity of the Zn ion and H ion usually are shown. Usually we write (g) after H2. Finally, usually we add a comma and Pt since H2 gas is non-conductive. If these were 1 M concentrations I would do it this way. Zn|Zn^2+(1M)||H...
May 20, 2015

physical science
Because the column of air is not as high (nor as dense) which means it has less weight.
May 20, 2015

Chemistry
delta T = i*Kf*m We need i, Kf, m. i = 2 for NaCl Kf we know for water is 1.86 c/m 1.25 kg ice eventually becomes 1.25 kg water. So we need m. m = mols/kg solvent. We have kg solvent so we need mols. mols NaCl = grams/molar mass. You know grams and molar mass, solve for mols ...
May 20, 2015

Chem
For #1. 0.01 M HCl. So H^+ = 0.01 M and since (H^+)(OH^-) = 1E-14, then (OH^-) = 1E-14/0.01 = 1E-12 M For #2. (NaOH) = 0.001 M so (OH^-) = 0.001 M Then (H^+)(OH^-) = 1E-14 and (H^+) = 1E-14/0.001 = 1E-11 M I'm confused by your question. If you know (H^+) OR (OH^-) you ...
May 20, 2015

Chem
(H^+) from HCl = (HCl) since HCl is 100% ionized. Then (H^+)(OH^-) = Kw = 1E-14 That allows you to calculate OH^-, the pH = -log(H^+). For NaOH, it is 100% ionized; therefore, OH^- = (NaOH). Then solve for H^+ and pH. Ba(OH)2 is a strong electrolyte; therefore, [Ba(OH)2] = 0....
May 20, 2015

Chemistry
Answered in your previous post. I would correct you on the carbon dioxide. That carbon(2) oxide technically means carbon(II) oxide and that means carbon with a valence of 2; however, CO2 has carbon with a valence of 4. Carbon dioxide should be called carbon dioxide and should ...
May 20, 2015

Chemistry
You CAN form two products. K2CO3 forms first. Continued passage of CO2 produces KHCO3.
May 20, 2015

Chemistry
See my responses above for CO2 vs CO.
May 20, 2015

Chemistry
You could try this yourself and see what happens but I believe the solution cools which makes it endothermic.
May 20, 2015

Chemistry
The burning candle is extinguished (because there is no oxygen to sustain the flame).
May 20, 2015

CHEMISTRY
1.836 g/mL x 50 mL = ?
May 20, 2015

chemistry
2 m is 2 mols/kg solvent 2 mols NaOH = 2*40 = 80 g NaOH Total mass solution is 1000 + 80 = 1080 g. mass = volume x density. You know the density and mass, solve for volume, then M = mols/L
May 20, 2015

physical science
momentum = mass in kg x speed in m/s. You will need to change 12 mph to m/s. 1 mph = 0.447 m/s.
May 19, 2015

physical science
You must provide much of this informaton from your text/notes/other sources. Convert 5 lbs Au to grams. There are 453.6 g in 1 lb. Look up the melting point of Au, in degrees C and convert that to kelvins. That is done with K = 273 + C. Look up the specific heat Au. Look up ...
May 19, 2015

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