Saturday
February 6, 2016

Posts by DrBob222

Total # Posts: 51,313

chemistry
M HI = mols/L = ? M H2 = mols/L = ? M I2 = mols/L = ? Then substitute the M of each into the Keq expression and solve for K.
September 14, 2015

Chemistry
q = mols H2O x heat fusion (in kJ/mol) = ?
September 14, 2015

chemistry
Use the Arrhenius equation. I would use the time to determine a rate constant for each. 1 egg in 4.7 min = 1/4.7 = ? and 1/4.4 = ? Substitute these for k1 and k2, use T1 and T2 and solve for Ea. Post your work if you get stuck.
September 14, 2015

Chemistry
q = mass Al x specific heat Al x (Tfinal-Tinitial)
September 14, 2015

chemistry
See your post above.
September 14, 2015

chemistry
The unit in the problem for k is sec-1 which means this is a first order reaction. ln(No/N) = kt No = 1.52 M N = ? k = given t = 5 min Solve for N. For part b, You know No and N, fraction remaining is N/No. Subtract from 1.0 to find fraction decomposed. Post your work if you ...
September 13, 2015

Chemistry
I assume this is for the H atom. E = hc/wavelength You have h,c,wavelength, solve for E. E = 2.180E-18(1/1^2 - 1/x^2) Solve for x. Post your work if you get stuck. This site will tell you the answer to check what you find. https://en.wikipedia.org/wiki/Hydrogen_spectral_series...
September 13, 2015

chemistry
Use the Arrhenius equation and solve for the k needed. If you need further assistance, please explain what you don't understand about this.
September 13, 2015

Chemistry
I don't understand your problem. This is just a case of substituting the numbers into the Keq expression and calculating K.
September 13, 2015

Chemistry
See you other post.
September 13, 2015

Chemistry
Some thing is omitted in this problem.
September 13, 2015

chemistry
What about it?
September 13, 2015

Chemistry
It's neither of your proposals. It's mols ethanol = 2.2/46.08 = ? Then mols C = 2*mols ethanol.
September 13, 2015

Chemistry
As of 2000 the most acid rain falling in the U. S. has a pH of about 4.3. https://www.google.com/search?q=pH+acid+rain&ie=utf-8&oe=utf-8
September 13, 2015

Chemistry (Check)
#1. The answer is correct at 3 but your electron configuration is not right. You have 10 electrons and N has only 7. #2. not correct. #3. 2 electrons is right but what's with the electron configuration? I see no need for that and certainly no use for it.
September 13, 2015

Chemistry (Check)
A poorly written question. -3 is correctly identified; however, since that is not correct we don't know what else might be wrong since the first quantum number is wrong. But the question implies, at least, that there are others errors. #2 is ok but you need to say m(l) = 1...
September 13, 2015

Chemistry (Check)
I think you are on the right track but I don't think you've answered the question. For #1, Be is H 2s2 but the alkaline earth metals are not that but Ne 2s2 or Ar 2s2 etc. I think the questions is asking for the GROUP so I would answer group IIA See my notes on #1. For...
September 13, 2015

Chemistry
I can't tell what you're doing but note that the Rydberg constant for H is NOT the number you have listed.
September 13, 2015

Chemistry
Here is how you do the B. Find a set where the only change is to B. That is set 1 and set 2. A is the same concentration, B is different, C is same. So rate = k(A)^x*(B)^y*(C)^z Since A and C are the same we can eliminate those (and k is the same so that is eliminated also). ...
September 13, 2015

Chemistry (Check)
A and B are not right. By highest wavelength do you mean the longest? The longest wavelength is 121.6 nm and the shortest is 91.2 nm The shortest wavelength is the highest energy since E = hc/wavelength C1 is ok. I don't know what C2 means.
September 13, 2015

Chemistry
Yes, delta T is 0.69. Then new freezing point is 79.4-0.69 = ? If your prof watches significant figures be careful with the final answer.
September 13, 2015

chemistory
Are you sure of the parts of the equation. I suspect you mean MnO4^- instead of Mn4^- and C2O4^2- instead of what you have and CO2 instead of CO3^2-; i.e., I think you want MnO4^- + C2O4^2- ==> MnO2 + CO2 and this is in basic solution.
September 13, 2015

chemistry
volume = length x width x height = ? cc Then density = mass/volume = ?
September 12, 2015

science
I don't buy III being correct.
September 12, 2015

science
Check the last two.
September 12, 2015

riddle
I would say none. The other 19 flew away.
September 12, 2015

Chemistry Lab
You don't provide enough information for me to know if you have both equations or just one reacting. If the first one only, it is (0.75/55.85) x (1 mol Cu^2+/1 mol Fe) = ?; then M CuSO4 = mols CuSO4/L CuSO4. You know mols and M, solve for L. If the second one only, it is (...
September 12, 2015

Chemistry
Yes and I'm pleased that you caught that (those) typos. 100 L is 100E3 mL and 100E3 mL x 1.00 g/mL = 1E5 g.
September 11, 2015

Chemistry
If you assume the density of water is 1.00 g/mL, then 1000 L H2O will have a mass of 1000 grams. Then q = mass H2O x specific heat H2O x (Tfinal-Tinitial)
September 11, 2015

chemistry
3A. The fuel is the candle wax. The rest of the answer is ok. 4 is ok. 5. I can't be sure what you did but from your answer I have assumed you measured a liquid with a pipet, dispensed into a container, WEIGHED the liquid from the pipet and calculated the density from that...
September 11, 2015

chemistry
q = mass H2O x specific heat H2O x (Tfinal-Tinitial)
September 11, 2015

Chemistry
I gave you a link earlier. What trouble are you having?
September 11, 2015

chemistry
You don't provide enough information for us to be helpful.
September 11, 2015

Chemistry
You might compare the H-Cl bond with the H-HSO4 bond (or H/HSO4 + H/SO4). For the net ionic equation that looks like the difference.
September 10, 2015

chem intro
rate = d(A)/dT rate = (1/3)*d(B)/dT
September 10, 2015

Chemistry URGENT!
I would do it this way. 0.5 g produces 9.72 kJ so how much will you get from 2*26.98? 9.72 kJ x (2*26.98)/0.5) = ?
September 10, 2015

Chemistry VERY URGENT PLEASE
It depends upon exactly hot it gets; i.e., how much it is heated but these problems usually mean you are driving off the water and not decomposing the water. MgSO4.7H2O + heat ==> MgSO4 + 7H2O
September 10, 2015

Chem
Read significant figures and rounding here. http://www.chemteam.info/SigFigs/SigFigs.html
September 10, 2015

Chemistry
Heterogeneous just means that the mixture can be separated into different materials physically. Oil and water is heterogeneous. granits also. Salt dissolves completely in water; it is a solution. You can dip a spoon into oil and water and come up with different amount of oil ...
September 10, 2015

Chemistry
1 m = 10^9 nm 0.00267 m x (10^9 nm/m) = ? Note that I arranged the factor so that m cancels and leaves nm for the units of the answer.
September 10, 2015

Chemical Science
baking soda is NaHCO3. Na2CO3 NaOH KOH Ba(OH)2 Ca(OH)2 LiOH RbOH Mg(OH)2 Sr(OH)2 Surely that is enough.
September 10, 2015

chem
mass = volume x density volume Hg = mass/density = 500/13.55 = ? 100-volume Hg = ? mL H2O to be added.
September 10, 2015

chemistry
1 is -1/2 2 is +1/4
September 10, 2015

AP Chemistry
M AgNO3 = grams AgNO3/L solution = ? M AgNO3 = grams AgNO3/0.042 = ? Therefore, to find M AgNO3 we must find grams AgNO3. We have the volume in L already. The Ag2CrO4 gives us a way to find the mass AgNO3 we started with. 2AgNO3 + Na2CrO4 ==> Ag2CrO4 + 2NanO3 mols Ag2CrO4...
September 10, 2015

Chemistry
Then why did you repost the same question above and waste my time showing you exactly how to do it?
September 9, 2015

Chemistry2
Yes, #1 is right. To do #2, look at your equation and fill in the blanks but I will use symbols to save space. Cl2 + 2KBr ==> 2KCl + Br2 4.0...13.4.....8.4.....x Remember the Law of conservation of mass; i.e., matter is not created or destroyed. Therefore, since you have 17...
September 9, 2015

science
The jetliner is moving at 600 km/hr. You are moving at 600 km/hr. The pillow and everything else in the cabin is moving at 600 km/hr. The speed relative to the ground is 600 km/hr for the pillow. The speed of the pillow relative to your lap is zero (because both of you are ...
September 9, 2015

chemistry
I use the rule for 0.5 to round to the even number; i.e., I would round to 760 torr. I would round 758.5 to 758.
September 9, 2015

Chemistry- PLEASE HELP
Both of these questions can be answered with a basic knowledge of chemistry. 1. Carbonate or bicarbonate ions fizz when an acid is added (HNO3, HCl, CH3COOH, etc) and fizzing is due to the release of carbon dioxide, CO2. The reaction with HCl is Na2CO3 + 2HCl ==> H2O + CO2...
September 9, 2015

CHEMISTRY
For Pb3O4, Pb is overall a 8/3 for each Pb. You can read about how this happens here. Pb3O4 is a mixture. https://answers.yahoo.com/question/index?qid=20130525034348AA6MFHx
September 9, 2015

CHEMISTRY
1. Indicate the oxidation number of carbon and sulfur in the following compounds. A) CO= +2 C) Na2CO3= +4 E) CH4= -4 G) SO2= +4 I) Na2SO4= +6 K) Na2S303= +2 OK if that is Na2S2O3 M) SCl2= +2 O) SOCl2= +4 2.) Indicate the oxidation number of phosphorous, iodine, nitrogen, ...
September 9, 2015

Chemistry
2*Na + S + 4*O + 10*H2O
September 9, 2015

Chem-HELP
You can go to google and type in define:aliquot and get definitions. 1. A part of it. For example, if you have a beaker containing exactly 50.00 mL and you withdraw 25.00 mL of that, you have withdrawn a 25 mL aliquot. 2. When a solid and liquid are mixed and the solid does ...
September 9, 2015

Chemistry
Hot flames tend to create hot spots and as the solution evaporates it sometimes gets overheated and the liquid becomes superheated. That often creates "bumping" in which the hot spot erupts and that is likely to spatter any solid. If you are doing quantitative work ...
September 9, 2015

@ Damon--Chemistry2
That's a much better answer than the one I gave two/three days ago. I'm still trying to find the limiting reagent.
September 9, 2015

Chem
chloride Cl^- sulfate SO4^2- sodium , Na Na^+ bicarbonate HCO3^- carbonate etc bromide etc fluoride etc
September 9, 2015

Chemistry
There are easier ways to do this but I think this is the best way to go about it. I would change the kg to grams. mols Fe = grams Fe/atomic mass Fe = ? Using the coefficients in the balanced equation, convert mols Fe to mols Fe2O3. That is mols Fe x (1 mol Fe2O3/2 mols Fe...
September 9, 2015

Chemistry
H atoms in H2O = 3.70E25 x (2 H atoms/1 H2O molecule) = ? H atoms in NH3 = 7.10E24 x (3 H atoms/1 NH3 molecule) = ? Total = sum.
September 9, 2015

Chemistry
A. q = mass H2O x specific heat H2O x (Tfinal-Tinitial) B. 1 cal = 4.184 J C. Can you take C from here.
September 9, 2015

Chemistry
See my comment under your first post below. I have no way of knowing what the prof is thinking and it's obviously not clear in the problem. Your two answers are right but you must now whether the prof want electronic geometry or molecular geometry to answer the question ...
September 9, 2015

Chemistry
Yes and No. The answer is 1 and that is C2H4. The so-called "double bond" in NO3^- and SO2 are not real double bonds although we draw double bonds with the Lewis dot structure. Remember that there are resonance forms so these double bonds are only figments of our ...
September 9, 2015

Chemistry
HClO3 is by far the strongest acid of those listed. You could look up the Ka values and eliminate some of them. Just knowing a little chemistry eliminates 1,2,4,and 6.
September 9, 2015

Chemistry
I didn't check your work but I came out with the same value at the end.
September 9, 2015

Chemistry
I didn't check the math but the procedure is correct and I see you converted all of the C to K first. That's good.
September 9, 2015

Chemistry
Carl, what's with all the names? Jim, Carl, George, Blaine et al. You confuse us when you do this and it makes it much harder to help you.
September 9, 2015

chemistry
Add chloride ion to ppt AgCl.
September 9, 2015

chemistry
mass = volume x density You know mass and density, solve for volume.
September 9, 2015

chemistry
mols biphenyl = grams/molar mass = ? molality biphenyl = mols/kg solvent delta T = Kf*m. Solve for delta T. Then subtract delta T from 6.5 to find the new freezing point.
September 9, 2015

CHEMISTRY
I prefer to write that as copper(II) nitrate. That can most easily be produced with copper metal and nitric acid. Your classmate is El Wrongo!. I can take AgNO3 and react it with KCl to produce AgCl and KNO3. I can separate those compounds and react either or both with ...
September 8, 2015

chemistry
13.2 gal x (3.78 L/gal) = ?L ?L x (1000 mL/1 L) = ? grams = volume x density. You know volume in mL and density in g/mL so you can calculate grams.
September 8, 2015

Chemistry 142
Change 10 km to miles. Change 42 minutes and 23 seconds to seconds and divide by 60 to change to minutes and divide by another 60 to change to hours. Then distance in miles/time in hours = ?
September 8, 2015

Chemistry
This is not a chemical property since you have iron to start and iron at the end. See here for the other two. https://en.wikipedia.org/wiki/Intensive_and_extensive_properties
September 8, 2015

Chemistry
Type of reaction means a. decomposition b. single replacement c. double replacement d. redox etc.
September 8, 2015

Chem
Balanced molecular equation. 2AuCl3(aq) + 3Mg(s) ==> 3MgCl2(aq) + 2Au(s) To convert to ionic. 1. gases remain as molecules 2. solids remain as molecules 3. strong electrolytes are displayed as ions. 4. weak electrolytes remain as molecules. From above, AuCl3 will be split. ...
September 8, 2015

Chem
Look at the Mg/AuCl3 post above.
September 8, 2015

Chem
CuCl2(aq) + K2CO3(aq) ==> 2KCl(aq) + CuCO3(s) Cu^2+(aq) + CO3^2-(aq) ==> CuCO3(s)
September 8, 2015

Chemistry
All are correct. Good work. Your system is working very well. Here is my system. kilo hecto deka unit of gram, liter, meter deci centi milli 1000 g to kg. I put my pencil on g and count up to kg. That is 3 so I move the decimal 3 places to the left (since I'm going UP) so ...
September 8, 2015

Science, chem
I don't know about this being a method; it is a procedure for doing the job. How many mols do you want? That's M x L = ? Then mols = grams CuSO4*5H2O/molar mass CuSO4*5H2O = ?. Place that many grams CuSO4*5H2O in a 100 mL volumetric flask, add some water, swirl until ...
September 8, 2015

Chemistry
pH = pK2 + log(base)/(acid) 7.4 = pK2 + log (base)/(acid) Solve for (base)/(acid) = ?. That is equation 1. Then base + acid = 500 x 0.3 is equation 2. Solve those two equations simultaneously for base and acid (in millimoles since 500 x 0.3 gives millimols). That gives you ...
September 8, 2015

Chemistry
Yes, Al is amphoteric and will dissolve in acids and bases.
September 8, 2015

Chemistry
Ko/d = (org layer)/(aq layer) K = 3.5 Let x = wt in aq layer Then 10-x = wt in org layer 3.5 = (10-x)/(100)/(x/60) Solve for x Do that three times for 3 extractions.
September 8, 2015

chemistry
mols H2SO4 = grams/molar mass = ? M = mols/L solution = ?
September 8, 2015

Organic Chemistry
Isn't it less soluble at 40 C?
September 8, 2015

Chemistry
The problem is that you didn't quite follow my instructions. I found the mass of Carbon (4.61/44g)*(1 mol C/1 mol CO2)=.1047 What you have done here is to calculate MOLES C, not grams C. Multiply by 12 to get grams C. I found the mass of Hydrogen (.94/18g)*(2 mol H/1 mol ...
September 8, 2015

Chemistry 2
I assume 50 mL H2O weighs 50 g. q = mass H2O x specific heat H2O x (Tfinal-Tinitial) Then q/gram = q/5 and delta H = (q/5) x (molar mass CaCl2) and convert that to kJ. Remember that if the T increases then the heat from the rxn is exothermic and that makes delta H negataive.
September 8, 2015

science
Add this site to what Ally has written. http://www.chemteam.info/Redox/Redox.html
September 7, 2015

Chemistry
Convert 4.61 g CO2 to g C. 4.61 x (atomic mass C/molar mass CO2) = ? Convert 0.94 g H2O to g H. 0.94 x (2*atomic mass H/molar mass H2O) = ? g O = 2.20- g H - g C = ? Convert grams to mols mols C = grams/atomic mass C mols H = grams/atomic mass H mols O = grams/atomic mass O ...
September 7, 2015

Chemistry
The IO- is hypoiodite ion. Since you named ClO- correctly, I'm surprised you miss missed the IO- because that's the same system. #2 looks ok.
September 7, 2015

Chemistry
Jessica, I don't understand the problem.
September 7, 2015

Chemistry
The dry vs wet means that when you collect a gas over water, the total pressure is what you read on the room manometer and that total pressure is the pressure of the CH4 + the vapor pressure of H2O at that temperature. You can look up the vapor pressure of water at the ...
September 7, 2015

AP Chemistry
Sierra, Allyson, ? We can help you better if you don't change screen names. This is done the same way as the earlier question that I showed you. I'll be glad to answer is questions about the procedure but you need to learn to do these yourself.
September 7, 2015

AP Chemistry
That looks ok to me but you have too many digits in your answer. The 20.7 number limits the number of significant digits to three, therefore, your answered should be rounded to 14.5 g Fe.
September 7, 2015

AP Chemistry
It's just a matter of converting the mass of one material to another. mm stands for molar mass and am stands for atomic mass. You want to convert 20.7 g Fe2O3 to mass Fe initially. How many mols Fe2O3 do you have? mols Fe2O3 = grams Fe2O3/mm Fe2O3 = ?. mols Fe = ? x (2 mol...
September 7, 2015

Chemistry
Group A ions are isoelectronic with their nearest noble gas. C and Si have four electrons in the outside shell thus they have an even tendency to lose four electrons or to gain four electrons. Therefore, they do neither; rather, they share eight electrons with other elements ...
September 7, 2015

Chemistry
inert
September 7, 2015

AP Chemistry
This is a limiting reagent (LR) problem and the way you know that is that amounts are given for BOTH reactants. Yes, balance the equation first. It would have been nice to do so and I could check the result. 1. Balance the equation. 2a. Convert 3/79 g N to mols. mols = grams/...
September 7, 2015

chemistry
M + 2HCl ==> MCl + H2
September 7, 2015

CHEMISTRY URGENT HELP
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7481.html
September 7, 2015

orgolab
1. (307 g/100 mL) x 1 mL = 3.07g so 1 g will completely dissolve. 2. approximately zero but a little less than zero. 3. (115 g/100) x 1 mL = 1.15 so none will come out of solution since it can hold 1.15 and you have only 1.0 g.
September 7, 2015

Chemistry
340 x (185/1000) = ?
September 7, 2015

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