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April 16, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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chemistry
[(g solute)/(g solution)]*100 = % g solute = x g solution = 24 % = 13.5 Substitute and solve for x
Thursday, March 27, 2014 at 6:12pm

analytical chemistry
Use the Henderson-Hasselbalch equation.
Thursday, March 27, 2014 at 6:10pm

chemistry
Cu(NO3)2(s) + H2O ==> Cu^2+(aq) + NO3^-(aq)
Thursday, March 27, 2014 at 6:08pm

Chemistry
Look at your cellulose balance above and see how I did that step by step. 2Fe + O2 ==> 2FeO I don't understand why you have trouble with that. 4Fe + 3O2 ==> 2Fe2O3 This one can be a little trickier but here is how I do it. Fe + O2 ==> Fe2O3 I start a little ...
Thursday, March 27, 2014 at 6:07pm

Chemistry
In the end for the carbon 3 C --> CO + C + CaCO3 so in the end we need 3 C atoms for every molecule of CaCO3 C = 12 g Ca = 40 g 3O = 3*16 = 48 g so CaCO3 = 100 g/mol so we get 7.90 mols of CaCO3 for that we need 3*7.9 = 23.7 mols of C 23.7 * 12 = 284.4 grams of Carbon
Thursday, March 27, 2014 at 6:06pm

Chemistry
10.00 mL of an unknown base solution is titrated with .100 M HCl solution. The pH versus the volume of NaOH added is shown below. There is a graoh where there are two dotted lines signifying a pH: the highest at pH 6.31 and the lower at pH 3.92. What is the pOH pf the solution...
Thursday, March 27, 2014 at 5:58pm

chemistry
C6H10O5 + O2 ==> CO2 + H2O Here is what I do. Balance C since you know you must have 6C on the right. C6H10O5 + O2 ==> 6CO2 + H2O Next look at H. There are 10 on the left so we need 10 on the right. C6H10O5 + O2 ==> 6CO2 + 5H2O Now we know for sure, since the 6 and 5 ...
Thursday, March 27, 2014 at 5:54pm

Chemistry
Ecell = Eocell + (0.0592/#e)log(Pb^2+)/(Pb^2+) Ecell = 0.1776 Eocell= I don't have my text handy but I think this is -0.126. You should verify that. #e = 2 For the log term, the top number there is 1M and the lower number is x. You solve for x
Thursday, March 27, 2014 at 5:46pm

Chemistry
How many grams of C would be necessary to produce 790. grams of CaCO3 by the sequence of reactions shown below? Step 1: CaO + 3C → CaC2 + CO Step 2: CaC2 + N2 → CaCN2 + C Step 3: CaCN2 + 3H2O → CaCO3 + 2NH3
Thursday, March 27, 2014 at 5:27pm

CHEMISTRY
H2S ==> SO2 mols H2S = 20.0g/molar mass = approx 0.6 but you need to do it more accurately. There is 1 mol S in H2S and 1 mol S in SO2; therefore, you should be able to produce 0.6 mols SO2. Then g = mols x molar mass. Remember to do the math yourself because 0.6 is an ...
Thursday, March 27, 2014 at 5:22pm

Chemistry Help Please!!!
Cu^2+ + 4NH3 ==> Cu(NH3)4^2+ blue. May be pale blue in very dilute solutions but more often is a deep blue color. Ni^2+ behaves similarly but not the same color.
Thursday, March 27, 2014 at 5:18pm

Chemistry
After mixing but before reacting the concns are (Ag^+) = 0.0023/2 = 0.00115M (CN^-) = 0.21/2 = 0.105M I've divided by 2 since equal volumes of each have been added which means both dilute each other by a factor of 2. Then we do an ICE chart. ..........Ag^+ + 2CN^- --> ...
Thursday, March 27, 2014 at 5:15pm

Chemistry
Silver ion reacts with excess CN− to form a colorless complex ion, Ag(CN)−2, which has a formation constant Kf=3.0×1020. Calculate the concentration of Ag+ in a solution prepared by mixing equal volumes of 2.3×10−3M AgNO3 and 0.21M NaCN.
Thursday, March 27, 2014 at 4:47pm

chemistry
PV = nRT where R = 0.0821 atm.L / K.mol NH2CONH2 = (14.01)(2)+(1.01)(4)+(12.01)+(16) = 60.07 n = 500 g/60.07 g = 8.32362244049 = 8.3236 mol of NH2CONH2 = 16.6472 mol of NH3 (1.5)V = (16.6472)(0.0821 atm L / K mol)(298.15 K) (1.5)V = 407.492076028 V = 271.661384019 271.66 L of ...
Thursday, March 27, 2014 at 4:17pm

Chemistry Help Please!!!
What initially forms as pale blue and pale green precipitates when NH3(aq) is added to [Cu(H2O)6]^2+ and [Ni(H2O)6]^2+ solutions, respectively?
Thursday, March 27, 2014 at 4:01pm

CHEMISTRY
HOW MANYMOLES OF SULFUR DIOXIDE CAN BE PRODUCED FROM 20.0G OF HYDROGEN SULFIDE?
Thursday, March 27, 2014 at 2:46pm

Chemistry
But I thought that the enthalpy of a reaction was dependant on the ratio of moles in the products vs moles in the reactants, not the limiting reagent..
Thursday, March 27, 2014 at 1:03pm

general chemistry
Mg(s) + ZnSO4(aq) ==> MgSO4(aq) + Zn(s) 1. How do you know Mg will displace Zn? Look at the activity series. A metal will displace any ion below it. Mg is above Zn; therefore, it will displace Zn^+2. Here is a chart.
Thursday, March 27, 2014 at 12:32pm

Chemistry
The measured potential of the following cell was 0.1776 volts: Pb|Pb2+(??M)||Pb2+(1.0M)|Pb Calculate the electrode potential of the unknown half-cell(anode). Not sure how to approach this, considering the molarity is unknown. There isn't a lot of space on the page for the ...
Thursday, March 27, 2014 at 12:26pm

chemistry
I do not understand how to right a balanced equation for the combustion of cellulose in oxygen to produce carbon dioxide and water vapor. I know that cellulose is C6H10O5 but I don't understand how to balance. Thanking you in advance for your help.
Thursday, March 27, 2014 at 11:51am

Chemistry
I am having a hard time figuring out how to write a balanced equation for the reaction of iron and oxygen to produce iron(II) oxide. I also need a balanced equation for the reaction of iron and oxygen to produce iron (III) oxide. I would appreciate any and all help. Thanking ...
Thursday, March 27, 2014 at 11:46am

chemistry
write a reaction that show solid copper (II) nitrate dissociating.
Thursday, March 27, 2014 at 9:32am

Chemistry
a balloon has a volume of 2.0 L at room temperature (27 degrees celsius). at what temperature would the balloon have a volume of 2.0L?
Thursday, March 27, 2014 at 7:55am

analytical chemistry
What volume (in liters) of 0.96 M KOH solution should be added to a 0.130 L solution containing 10.2 g of glutamic acid hydrochloride (Glu, FW=183.59; pKa1=2.23, pKa2 =4.42, pKa3=9.95) to get to pH 9.90?
Thursday, March 27, 2014 at 4:47am

chemistry
calculate the grams of solute neede to prepare 24 grams of a 13.5% by mass scurose (c12h22o11) solution
Thursday, March 27, 2014 at 2:39am

Chemistry
I would really like to understand how to do these problems, because my exam is coming up in a few weeks. I still cannot comprehend how you can tell if a system is is positive or negative according to reaction. For #1, I presume it is E if it is spontaneous at all temperatures...
Thursday, March 27, 2014 at 1:58am

Chemistry
How would you exactly start the first problem? My thermodynamic skills is a bit rusty. I am assuming I have to use ΔH°f under the given reaction..? But then..we barely covered ΔG° in class. Am I to use this equation, ΔG° = ΔH° - T ΔS&...
Thursday, March 27, 2014 at 1:31am

Chemistry
IT doesn't tell me anything. WHAT is incorrect? What number did you get? If you used my numbers I'm not surprised it (the answer you obtained) is incorrect. Did you read where I said it was approximate? Did you work it out from the beginning. Probably not.
Wednesday, March 26, 2014 at 11:55pm

Chemistry
It is incorrect
Wednesday, March 26, 2014 at 11:43pm

Chemistry
Au, Pt, Sn, Ag in that order. q = mass x specific heat x delta T Solve for specific heat or sp.h. sp. h. = q/m*delta T So for the same m and delta T, small sp.h. requires small q; large sp.h. require large q. But you could think of an example and get the same result. If I heat...
Wednesday, March 26, 2014 at 11:41pm

Chemistry
The factor to which you refer is i, the van't Hoff factor. It is 4 for AlCl3.
Wednesday, March 26, 2014 at 11:29pm

Chemistry
Why not post one of them and let us find the error. This way we're running in circles.
Wednesday, March 26, 2014 at 11:25pm

Chemistry
I don't think so. Post your work and I'll find the error. And you need to define x.
Wednesday, March 26, 2014 at 11:23pm

chemistry
Do you have a question?
Wednesday, March 26, 2014 at 11:20pm

Chemistry
I worked this for you about 4-5 hours ago.
Wednesday, March 26, 2014 at 11:20pm

Chemistry
See your post on AB3
Wednesday, March 26, 2014 at 11:19pm

Chemistry
2.30 g/L = 2.30/333 mols/L = approx 0.007 M but this is an estimate. ..........AB3 ==> A^3+ + 3B^- I........solid.......0......0 C........solid...0.007...3*0.007 E........solid...0.007....0.021 Ksp = (A^3+)(B^-)^3 Ksp = (0.007)(0.021)^3 = ? Check my work.
Wednesday, March 26, 2014 at 11:18pm

Chemistry
Well, its definitely too late to help you, but I'll post this for the benefit of others. None of the listed atoms are definitely present, as there is no way to tell from the limited information. Likewise, we know from the chart of the seperation of cations that Ba2+ and ...
Wednesday, March 26, 2014 at 10:54pm

Chemistry
generic salt, AB3, has a molar mass of 333 g/mol and a solubility of 2.30 g/L at 25 °C. What is the Ksp of this salt at 25 °C?
Wednesday, March 26, 2014 at 10:53pm

Chemistry
A generic salt, AB, has a molar mass of 159 g/mol and a solubility of 3.20 g/L at 25 °C. What is the Ksp of this salt at 25 °C?
Wednesday, March 26, 2014 at 10:38pm

Chemistry
a 4.000grams sample of aluminum metal is added to a solution containing 5.000grams of dissolved iron chloride. the reaction results in the formation of aluminum chloride and metallic iron. when the reaction is complete, unreacted aluminum remains, and this unreacted aluminum ...
Wednesday, March 26, 2014 at 10:13pm

chemistry
A solution is made with 2.0 g of substance that cause the temperature of 75.0 g of water to decrease from 23.1 C to 18.7 C. The specific heat of water is 4.18 J/g C.
Wednesday, March 26, 2014 at 9:56pm

Chemistry
he Ksp of mercury(II) hydroxide, Hg(OH)2, is 3.60 × 10-26. Calculate the solubility of this compound in g/L. I came up with x=2.8*10^-13
Wednesday, March 26, 2014 at 9:44pm

Chemistry
I am very confused. I tried several practice problems and am not getting them correct.
Wednesday, March 26, 2014 at 9:29pm

Chemistry
Hmmmm. saline should have a density greater than 1g/cc, here it is less :(50.433/60)
Wednesday, March 26, 2014 at 9:26pm

Chemistry
formula is correct, the issue is molality. 1.05/molmassK*.025 so, molmassK=1.05Kf/(.025*3.53)
Wednesday, March 26, 2014 at 9:24pm

Chemistry
Molarity=moles/volume=mass/(volume* molmass) mass=molarity*molmass*volume
Wednesday, March 26, 2014 at 9:21pm

chemistry
what is the balanced chemical equation and how do you find the percent yield of iron in the experiment?
Wednesday, March 26, 2014 at 9:18pm

Chemistry
What is the mass if solute dissolved in the indicated volume of each of the following solutions? (b) 4.25 L of 0.450 M KIO4g (c) 60.0 mL of 0.310 M ZnSO4g (d) 60.0 mL of 0.310 M Ni(NO3)2g
Wednesday, March 26, 2014 at 8:54pm

Chemistry
A hospital saline solution is analyzed to confirm its concentration. A 60.0 mL sample with a mass of 50.443 g is evaporated to dryness. (a) If the solid sodium chloride residue has a mass of 0.413 g, find the mass/mass percent concentration of the NaCl solution. % (b) Find the...
Wednesday, March 26, 2014 at 8:53pm

Chemistry
Vitamin K is involved in normal blood clotting. When 1.05 g of vitamin K is dissolved in 25.0 g of camphor, the freezing point of the solution is lowered by 3.53 °C. The freezing point and Kf constant for camphor can be found here. Calculate the molar mass of ...
Wednesday, March 26, 2014 at 8:51pm

Chemistry
Given that the vapor pressure of water is 17.54 Torr at 20 °C, calculate the vapor-pressure lowering of aqueous solutions that are 1.90 m in (a) sucrose, C12H22O11, and (b) aluminum chloride. Assume 100% dissociation for electrolytes. I got .5799 Torr for sucrose, ...
Wednesday, March 26, 2014 at 8:49pm

Chemistry
Which of the following substances could be heated from 20°C to 100°C most quickly? Assume identical heat sources are used on all substances. Specific Heat (J/g degrees C) Gold: 0.1291 Platinum: 0.1326 Silver: 0.2350 Tin: 0.2274 Can you please explain how you figured it...
Wednesday, March 26, 2014 at 7:36pm

Chemistry
ml ranges from -L to +L If L = 0, ml = 0
Wednesday, March 26, 2014 at 7:22pm

Chemistry
The problem with 4 is not the +/- 1/2, you can't have ml of one with ell = 0 m ell values are + ell to -ell. If ell = 0, you may have m ell of zero only. Can't be + one.
Wednesday, March 26, 2014 at 7:21pm

Chemistry
4 is out because with L = 0 you have no choice of ml = 1. wtih L = 0 ml = 0 and spin can be 1/2 or -1/2 ml = 1 is not allowed if L = 0
Wednesday, March 26, 2014 at 7:21pm

Chemistry
but on 4 the spin is Ms= -1/2
Wednesday, March 26, 2014 at 7:16pm

Chemistry
3) is out, spin is =/- 1/2 1) is out, negative L 2) is out , biggest L is n-1 or 2 4) is out, with L=0 you only have +/- 1/2 for spin, no ml - 1 5) looks possible 6) looks possible
Wednesday, March 26, 2014 at 6:59pm

Chemistry
Thank you so much!!!!
Wednesday, March 26, 2014 at 6:59pm

Chemistry
The principal quantum number, n, describes the energy level of a particular orbital as a function of the distance from the center of the nucleus. Additional quantum numbers exist to quantify the other characteristics of the electron. The angular momentum quantum number (ℓ...
Wednesday, March 26, 2014 at 6:35pm

english essay
Ofcourse, I know Science and Chemistry are not issues but I want to know an issue related to this particular subject.I do not If you understood or not.
Wednesday, March 26, 2014 at 6:26pm

english essay
What is the ISSUE? Science, Chemistry, and nature are not ISSUES. Example: Science Issue..Carbon dioxide is pouring into the atmosphere, causing climate change.
Wednesday, March 26, 2014 at 6:12pm

Chemistry
My original answer didn't post. I said that you don't say but obviously the Cu (metal???) must be laced in solution and it PROBABLY formed Cu^2+ in which case the ppt will be CuCr2O7. Try that.
Wednesday, March 26, 2014 at 6:11pm

english essay
* I need help writing research essay. The topic is to write about an issue or problem that you want to change. Well, I am mostly interested in Science, particularly Chemistry and Nature.
Wednesday, March 26, 2014 at 6:09pm

Chemistry
We have a problem here. You have Fe^2+ on the left and Fe^3+ on the right which means Fe has been oxidized. But there is no reduction. You can't have oxidation without reduction. I expect you meant Fe(NO3)3 on the left
Wednesday, March 26, 2014 at 6:08pm

Chemistry
See your other post.
Wednesday, March 26, 2014 at 6:03pm

Chemistry
"Determine the volume of a 0.925M K2Cr2O7 solution required to completely react with 5.28g of Cu." My attempted method for solving was to convert the 5.28g of Cu to moles, find moles of K2Cr2O7 using the mole to mole ratio, and then use M=mol/L to solve for volume. ...
Wednesday, March 26, 2014 at 4:54pm

Chemistry
"Determine the volume of a 0.925M K2Cr2O7 solution required to completely react with 5.28g of Cu." My attempted method for solving was to convert the 5.28g of Cu to moles, find moles of K2Cr2O7 using the mole to mole ratio, and then use M=mol/L to solve for volume. ...
Wednesday, March 26, 2014 at 4:54pm

chemistry
You can use the known value of osmotic pressure (0.305 atm) to solve the equation pi=i(MRT) where (i) is Van 't Hoff factor (1 since insulin is not ionic) R is the constant 0.0821 L atm / K mol, and T is temperature in Kelvin. So solving you get: 0.305=1(0.08206)(298) 0....
Wednesday, March 26, 2014 at 4:36pm

Chemistry
Complete ionic equation and net ionic equation for 2 K3PO4 + 3 Fe(NO3)2 --> 6 KNO3 + Fe3(PO4)2
Wednesday, March 26, 2014 at 4:09pm

Chemistry
I'm guessing but you need to decipher your post. Does CIE and NIE stand for complete and net ionic equation?
Wednesday, March 26, 2014 at 3:35pm

chemistry
Just to be sure we're on the same page my post could be misinterpreted. You are SUPPOSED to convert kJ/mol to J/mol. Using kJ/mol won't work.
Wednesday, March 26, 2014 at 3:34pm

Chemistry
I expect LR stands for limiting reagent. Your calculation of 560 J for q is correct. You added 100 x 0.1M = 10 millimols (0.01 mols) to 0.01 mols So your answer is 560 J/0.01 mol = 56000 J/mol or 56 kJ/mol
Wednesday, March 26, 2014 at 3:30pm

chemistry
Second try. My first one was deleted. 32.9150g = mass dish + Fe -30.7310g = mass empty dish ------------- +2.1840g = mass Fe %Fe = (mass Fe/mass Fe sample) = 2.1840/5.000)*100 = ? = approx 43.68% Note: I feel compelled to point out that this is a lousy procedure BECAUSE when ...
Wednesday, March 26, 2014 at 3:23pm

Chemistry
You need to decipher this post for us.
Wednesday, March 26, 2014 at 2:52pm

Chemistry
H2C2O4 + 2NaOH ==> Na2C2O4 + 2H2O mols H2C2O4 = grams/molar mass Using the coefficients in the balanced equation, convert mols H2C2O4 to mols NaOH. Then mols NaOH = M x L. You know mols and M, solve for L and convert to mL.
Wednesday, March 26, 2014 at 2:51pm

Chemistry
Let's call benzoic acid HBz and the benzoate ion then is Bz^- With HNO3, the added acid (HNO3) reacts with the base, Bz^-. Bz^- + H^+ ==> HBz With KOH, the added base (KOH) reacts with the acid, HBz. HBz + OH^- ==> Bz^- + H2O
Wednesday, March 26, 2014 at 2:46pm

Chemistry
CIE and NIE for 2 K3PO4 + 3 Fe(NO3)2 --> 6 KNO3 + Fe3(PO4)2
Wednesday, March 26, 2014 at 2:43pm

chemistry
Use the Henderson-Hasselbalch equation
Wednesday, March 26, 2014 at 2:43pm

chemistry
Fe + 2HCl ==> FeCl2 + H2 1 mol Fe = 1 mol FeCl2; therefore, 10 mol Fe = 10 mols FeCl2.
Wednesday, March 26, 2014 at 2:42pm

chemistry
a piece of metallic iron (10 moles) was dissolved in concentrated hydrochloric acid. the reaction formed iron (II) chloride and hydrogen gas. how many moles of iron (II) chloride were formed?
Wednesday, March 26, 2014 at 1:50pm

chemistry
URGENT!!! How many grams of sodium benzoate (NaC6H5CO2) must be added to 500 mL of 0.15 M benzoic acid (HC6H5CO2) to make a buffer solution with pH of 5.0? Assume no volume change upon sodium benzoate dissolution. Ka = 6.46 x 10-5 How would I go about this question?
Wednesday, March 26, 2014 at 1:29pm

Chemistry
Write the reactions that occur for the benzoic acid/sodium benzoate buffer when you react it with HNO3 and KOH. How would I go about writing it? Thanks.
Wednesday, March 26, 2014 at 1:20pm

Chemistry
How many milliliters of 0.242 M NaOH are required to exactly titrate 18.0 grams of H2C2O4?
Wednesday, March 26, 2014 at 1:06pm

CHemistry
gotta work with moles. How many moles H2SO3 in 36.86g? Since each mole of H2SO3 requires 1 mole of SO2, you need the same number of moles. So, convert back to g of SO2
Wednesday, March 26, 2014 at 12:05pm

CHemistry
SO2(g) + H2O(l)= H2SO(l) What mass of sulfur dioxide is needed to prepare 36.86 g of H2SO3(l)
Wednesday, March 26, 2014 at 11:54am

Chemistry
CIE and NIE for 2 K3PO4 + 3 Fe(NO3)2 = 6 KNO3 + Fe3(PO4)2
Wednesday, March 26, 2014 at 11:50am

chemistry
in an experiment, a 4.000grams sample of aluminum metal is added to a solution containing 5.000grams of dissolved iron chloride. the reaction results in the formation of aluminum chloride and metallic iron. when the reaction is complete, unreacted aluminum remains, and this ...
Wednesday, March 26, 2014 at 11:46am

chemistry
Kf ionic name
Wednesday, March 26, 2014 at 11:22am

Chemistry
Which nucleophile, when reacted with 1-bromopropane (CH3CH2CH2Br), would produce a thiol? OH- SH- I- -OCH3
Wednesday, March 26, 2014 at 11:15am

chemistry
Which nucleophile, when reacted with 1-bromopropane (CH3CH2CH2Br), would produce an ether? I- OH- -OCH3 SH-
Wednesday, March 26, 2014 at 11:14am

Chemistry
So my chem professor had a slide with a question that follows: If you combine 100 ml of 0.10 M HCl and 100 ml of 0.10 M NaOH, and find that the temperature goes up 0.67 degrees K  What is ΔH° for the reac/on: OH(aq)- + H+(aq)->H2O(l)(c H2O= 4.18 J/°C sg, ...
Wednesday, March 26, 2014 at 10:27am

University Chemistry (first year)
Hi I am 10. RP pls. Kimochi
Wednesday, March 26, 2014 at 3:39am

University Chemistry (first year)
Hi I am 10. RP pls.
Wednesday, March 26, 2014 at 3:36am

chemistry
NACL +HNO3 = HCL +NANO3 AGCL + HNO3= NO REACTION With regards from SHABAZ AHMED DAR ( VIVEKANANDA KENDRA VIDYALAYA) BARAGOLAI, ASSAM
Wednesday, March 26, 2014 at 2:39am

chemistry
143.5 g AgCl contains Ag = 108 2.87 g Agcl contains Ag = (108×2.87)/143.5 Answer= 2.16 g Thanks :) with regards from SHABAZ AHMED DAR (VIVEKANANDA KENDRA VIDYALAYA, BARAGOLAI, ASSAM)
Wednesday, March 26, 2014 at 2:26am

chemistry
ah you are right DrBob222. I converted kJ to J.
Wednesday, March 26, 2014 at 2:01am

Chemistry
molecules is not M. I would convert molecules to mol which will be mols/cc and convert that to mols/L which is M.
Wednesday, March 26, 2014 at 1:16am

chemistry
In fact, a rule of thumb in the kinetics business is that reaction rate can be doubled for every 10 degrees T. Since this ratio k2/k1 = about 2.05 I would guess T2 would be close to 365 or something like that.
Wednesday, March 26, 2014 at 12:39am

chemistry
I don't think so. 273 + C = K 273 + C = 17 C = ? not 290?? Second think I notice is that your calculated temperature decreased. k2 is about double k1 so wouldn't you think T would be higher. Did you convert kJ/mol to J/mol? That's a common error.
Wednesday, March 26, 2014 at 12:24am

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