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April 18, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
Chilling reduces the rate of the reaction. Boiling removes the enzyme. Oxygen reacts with both the enzyme and the citric acid but it reacts with citric acid first and will keep the browning away as long as the lemon juice is in excess.
Tuesday, March 18, 2014 at 3:08pm

Chemistry
I think your problem is the wrong formula. I believe that's dG = -2.303RT*log K
Tuesday, March 18, 2014 at 3:01pm

Chemistry
Consider the following hypothetical nuclear breakdown: Fermium-258 (Fm-258) loses three alpha particles and two neutrons. What is the new element that is formed (in terms of chemical symbol, atomic number and atomic mass)? I'm not sure how to express this in equation form...
Tuesday, March 18, 2014 at 3:00pm

Chemistry
A reaction has a standard free-energy change of –10.30 kJ mol–1 (–2.462 kcal mol–1). Calculate the equilibrium constant at 25ºC.? This is what I've done so far.. ∆Gº= -2.3 RT + log (K) -10.31 kJ = -2.3 (.0083145)(298) + log K -10.31 kJ...
Tuesday, March 18, 2014 at 2:52pm

chemistry
20.92 %
Tuesday, March 18, 2014 at 2:32pm

Chemistry
It is commonly known that freshly cut fruits turn a brownish color when exposed to the air for a number of minutes. This is due to the action of the enzyme polyphenoloxidase. It is also well known that the formation of the brown color can be prevented or slowed by chilling the...
Tuesday, March 18, 2014 at 1:38pm

Chemistry
a 2.500 g sample of a pure compound was analysed and found to contain 1.094 g of nitrogen.determine whether the compound is either NH4NO3 or NH4NO2 .show all by calculations.
Tuesday, March 18, 2014 at 1:22pm

Chemistry
1. Calculate the mass of each compound required to make 25mL of the following solutions: (a) 0.10 M Ni(NO3)2 • 6H2O (b) 1.0 M NaClO4 • H2O (c) 0.11 M trien (C6H18N4) 2. Calculate the concentrations of Ni2+ and trien in a solution prepared by mixing equal volumes of ...
Tuesday, March 18, 2014 at 11:14am

Chemistry
Oxygen gas, from the decomposition of KClO3, was collected by water displacement. The pressure and temperature in the lab during the experiment were 451.0 torr and 20.0 C. What was the partial pressure of oxygen?
Tuesday, March 18, 2014 at 11:06am

chemistry
Calculate the pH of a buffer system composed of 0.880 M C5H5N and 0.660 M C5H5NHNO3. The Kb for C5H5N is 1.70 x 10^-9.
Tuesday, March 18, 2014 at 10:41am

Chemistry
A 10.00 gram solid sample consisting of a mixture of sodium chloride and potassium sulfate is dissolved in 100.0 mL of water is combined with another 200.0 mL solution that contains excess aqueous lead(II) nitrate. Upon mixing the two solutions, a solid precipitate forms (it ...
Tuesday, March 18, 2014 at 10:21am

Chemistry
what would be the molality of a solution if 71g of Cl2 were added to 400 mL of acetone (D=0.788 g/mL)
Tuesday, March 18, 2014 at 10:21am

Chemistry
2NaN3(s) -> 2Na(s) + 3N2(g) What mass of sodium azide should be loaded in the device to ensure full inflation of the same air bag if the actual reaction can be expected to proceed to give only 83% yield of nitrogen gas?
Tuesday, March 18, 2014 at 10:20am

chemistry
2C3H6(g) + 2NH3(g) + 3O2(g) -> 2C3H3N(g) + 6H2O(g) A 150.0 liter steel reactor at 25 ºC is filled with the following partial pressures of reactants: 0.500 MPa C3H6, 0.800 MPa ammonia, and 1.500 MPa oxygen gas. If the reaction proceeds to 90% yield, and no side ...
Tuesday, March 18, 2014 at 10:19am

chemistry
2C4H10 + 13O2 -> 10H2O +8CO2
Tuesday, March 18, 2014 at 6:36am

chemistry
Balanced equation of the reaction that occurs when the butane in cigarette lighters burns in the presence of enough oxygen
Tuesday, March 18, 2014 at 6:25am

Chemistry
How would you start these problems? ...I suppose this is a continuation from this post: (replace the numbers with id=1395127807) But, I have yet figured out the ΔH ̊ and ΔS ̊ . But once that is figured out, how would I start problem #1? Also, for problem #2...
Tuesday, March 18, 2014 at 3:40am

Chemistry
Determination of Ksp, ΔG°, ΔH° and ΔS° for Ca(OH)2. *** Need help on problem #3 & #4 *** CALCULATIONS: 1. Calculate the average solubility of calcium hydroxide, Ca(OH)2, at each temperature. 2. Calculate the Ksp for Ca(OH)2 at each temperature. 3. ...
Tuesday, March 18, 2014 at 3:30am

Chemistry
A
Tuesday, March 18, 2014 at 2:56am

Chemistry
It does have an effect because B and C form only from A. If A were added to a gas to get B and C, then it would have no effect, but this is not the case.
Tuesday, March 18, 2014 at 1:39am

chemistry
33.01 g CO2 27.04 g H2O mols CO2 = 33.01/44 = ? = mols C. mols H2O = 27.04/18 = ? and that x 2 = mols H. Now find the ratio of C to H with C being no larger than 1.0
Tuesday, March 18, 2014 at 12:30am

Chemistry Check Please!!!
I think Eox = -0.771 and Ered = +1.36 Then 1.36 + (-0.771) = ? Your answer is right; I don't agree with what you called Eox. The anode is oxidized, yes, and that is an oxidation, yes. But the potential for that electrode is -0.771. The reduction potential is 0.771; the ...
Tuesday, March 18, 2014 at 12:14am

Chemistry Check Please!!!
Using a table of standard electrode potentials (as in Appendix M of your text), calculate the standard cell potential, Eo, for: 2 Fe2+(aq) + Cl2(g) 2 Fe3+(aq) + 2 Cl(aq). Answer: Anode: 2 Fe2+ 2 Fe3+ + 2 e Eox = 0.771 V Cathode: Cl2 + 2 e 2 Cl Ered = +1.36 V Enet = +0.59 V
Monday, March 17, 2014 at 11:39pm

chemistry
Combustion analysis of a hydrocarbon produced 33.01 g {\rm CO}_2 and 27.04 g {\rm H}_2{\rm O}. Calculate the empirical formula of the hydrocarbon. Express your answer as a chemical formula.
Monday, March 17, 2014 at 11:14pm

chemistry
See your post below.
Monday, March 17, 2014 at 9:44pm

Chemistry
See your other post.
Monday, March 17, 2014 at 9:44pm

Chemistry
3m = 3 mols KCl/1 kg solvent 1 mol KCl = estimated 74.5 but you should be more accurate than that. 3*74.5 = about 223g. So that is about 223g/223+1000 = 223g/1223 g solution % KCl w/w = (223/1223)*100 = >
Monday, March 17, 2014 at 9:42pm

Chemistry
Is that a typo first line. Perhaps should be CaCl2.6H2O. If so just add the two equations to obtain CaCl2(s) ==> CaCl2(aq) about -82 kJ/mol but that isn't exact.
Monday, March 17, 2014 at 9:38pm

Chemistry
(0.75g/20) = (x g/105.4) Solve for x.
Monday, March 17, 2014 at 9:11pm

Chemistry
mols = grams/molar mass. Substitute and solve for mols. m = molality = mol/kg solvent Substitute and solve for m. delta T = Kf*m Substitute and solve for delta T. Then subtract delta T from the normal freezing point of camphor.
Monday, March 17, 2014 at 9:05pm

Chemistry
find the freezing point of a solution containing 3 grams of a compound of molar mass 125 g/mol in 45 g of camphor
Monday, March 17, 2014 at 8:12pm

Chemistry
If 0.75 g of a gas dissolves in 1.0 L of water at 20.0 kPa of pressure, how much will dissolve at 105.4 kPa of pressure?
Monday, March 17, 2014 at 7:41pm

chemistry
CuNO3 molar mass = 63.5 + 14 + 3(16) = 125.5 grams/mol 8.22 g /125.5 g/mol = .0655 mols of the stuff .0655 mols/x liters = .59 mols/1 liter x = .111 liters
Monday, March 17, 2014 at 6:54pm

chemistry
8.22 g of CuNO3 is dissolved in water to make a 0.590M solution,what is the volume of the solution
Monday, March 17, 2014 at 6:48pm

chemistry
34
Monday, March 17, 2014 at 6:05pm

College Chemistry
How many moles of aluminum ions are present in 0.50 mole of Al2(SO4)3?
Monday, March 17, 2014 at 5:02pm

Chemistry
Dissolving solid CaCl2 H2O in a large volume of water is endothermic to the extent of 14.6 kj/mol. Also given: CaCl2(s)+6H2O(l)->CaCl2* 6H2O(s) delta H = -97.0 kj what is the heat of solution of anhydrous CaCl2 in a large volume of water?
Monday, March 17, 2014 at 4:43pm

Chemistry
Dissolving solid CaCl2 H2O in a large volume of water is endothermic to the extent of 14.6 kj/mol. Also given: CaCl2(s)+6H2O(l)->CaCl2* 6H2O(s) delta H = -97.0 kj what is the heat of solution of anhydrous CaCl2 in a large volume of water?
Monday, March 17, 2014 at 4:43pm

Chemistry
What is the percent KCL by mass in a 3.00 molal solution?
Monday, March 17, 2014 at 4:37pm

chemistry
What is the percent KCL by mass in a 3.00 molal solution?
Monday, March 17, 2014 at 4:36pm

chemistry
C = p*k C = 2.5*0.037 Solve for C in M. M = mol/L. You know L and M, solve for mol. mol = grams/molar mass. You know molar mass and mol, solve for grams.
Monday, March 17, 2014 at 4:15pm

Chemistry HELP URGENT PLEASE!!!
yes
Monday, March 17, 2014 at 4:09pm

chemistry
The Henry's law constant for CO2 at 20°C is 3.7*10^-2 M/atm. What mass of CO2 (in grams) is present in 355 mL of soda drink if the pressure of CO2 in the can is 2.5 atmospheres at 20°C? (Assume the solubility of CO2 in the soda is the same as water)
Monday, March 17, 2014 at 3:55pm

Chemistry HELP URGENT PLEASE!!! Check
Is the answer 1.76 A? Thank you!
Monday, March 17, 2014 at 3:26pm

Chemistry HELP URGENT PLEASE!!!
what current (in amperes) is required to plate out 2.85 g of Cr from a Cr^3+ solution in a period of 2.50 hr?
Monday, March 17, 2014 at 3:23pm

chemistry
thank you!
Monday, March 17, 2014 at 2:58pm

chemistry
See your post below.
Monday, March 17, 2014 at 2:47pm

chemistry
3Cl2 => 2CHCl3 mols CHCl3 = 7.20 Convert to mols Cl2. 7.20 mols CHCl3 x (3 mols Cl2/2 mols CHCl3) = ? Then ? mols Cl2 x molar mass Cl2 = grams.
Monday, March 17, 2014 at 2:46pm

Chemistry Help Please
Each of the following statements is false. Rewrite each so that it makes a correct statement about free energy. a. ΔGuniverse > 0 for any spontaneous process. b. ΔH = ΔG TΔS.
Monday, March 17, 2014 at 2:45pm

chemistry
Ag^+ + Cl^- ==> AgCl(s) Ba^2+ + SO4^2- ==> BaSO4(s) Cu^2+ + 2OH^- ==> Cu(OH)2(s) Add Cl^-, filter AgCl. Treat with Na2SO4 and filter BaSO4. Add NaOH. Filter Cu(OH)2.
Monday, March 17, 2014 at 2:37pm

chemistry
q = mass x specific heat x (Tfinal-Tinitial)
Monday, March 17, 2014 at 2:33pm

chemistry
Determine the specific heat of a material if a 27.3 g sample absorbed 44.2 J as it was heated from 293 K to 336 K.
Monday, March 17, 2014 at 2:14pm

chemistry
A laboratory instructor gives you a test tube containing Ag+ ,Ba 2+ , and Cu 2+ ions. Devise a reaction scheme that would allow you to selectively precipitate each of these ions. Write a balanced net ionic equation for each precipitation reaction.
Monday, March 17, 2014 at 1:50pm

chemistry
How many grams of CL2 are needed to produce 7.20 moles of chloroform?
Monday, March 17, 2014 at 11:26am

chemistry
How many grams of CL2 are needed to produce 7.20 moles of chloroform?
Monday, March 17, 2014 at 11:26am

chemistry
Is there a question here?
Monday, March 17, 2014 at 11:02am

chemistry
34.0g of NaOH in 500.mL of NaOH solution
Monday, March 17, 2014 at 1:47am

Chemistry
a solution is prepared by dissolving 22.0g of NaOH in 117.0g of water. The NaOH solution has a density of 1.15 g/mL. what is the Molarity(M) of the solution.
Monday, March 17, 2014 at 1:36am

Chemistry
I don't agree this answer. number %khp so high
Monday, March 17, 2014 at 12:54am

Chemistry
mols ZnO = grams ZnO/molar mass ZnO Using the coefficients in the balanced equation, convert mols ZnO to mols Au. Now convert mols Au to grams. g = mols x atomic mass.
Monday, March 17, 2014 at 12:03am

Chemistry
Gold can be recovered from sea water by re- acting the water with zinc, which is refined from zinc oxide. 2 ZnO(s) + C(s) −→ 2 Zn(s) + CO2(g) 2 Au3+(aq) + 3 Zn(s) −→3 Zn2+(aq) + 2 Au(s) The zinc displaces the gold in the water. What mass of gold can be ...
Sunday, March 16, 2014 at 11:55pm

CHEMISTRY
See your other post. Same process but you must correct for concns that are not 1M. Use the Nernst equation for that. Post your work if you get stuck.
Sunday, March 16, 2014 at 11:53pm

Chemistry Help Please
See your other post.
Sunday, March 16, 2014 at 11:48pm

CHEMISTRY
A voltaic cell is constructed that uses the following reaction and operates at 298 K: 2 Al(s) + 3 Mn^2+(aq) 2 Al^3+(aq) + 3 Mn(s). What is the potential, E, of this cell when [Mn^2+] = 0.10 M and [Al^3+] = 1.5 M?
Sunday, March 16, 2014 at 11:27pm

Chemistry Help Please
Using standard thermodynamic data from Appendix L of your text, calculate the equilibrium constant at 298 K for the following chemical reaction: CO(g) + H2O(l) CO2(g) + H2(g). Show work please! Thank you!!!
Sunday, March 16, 2014 at 11:21pm

Chemistry Help Please
Each of the following statements is false. Rewrite each so that it makes a correct statement about free energy. a. ΔGuniverse > 0 for any spontaneous process. b. ΔH = ΔG TΔS.
Sunday, March 16, 2014 at 11:18pm

Chemistry
Kate's (a) and (b) are correct, but (c) is incorrect. 6.00 M NaOH = (0.325 mol NaOH) / (mL NaOH) mL NaOH = (0.325 mol NaOH) / (6.00 M NaOH) With correct significant figures, the answer to (c) is 54.2 mL.
Sunday, March 16, 2014 at 11:00pm

Chemistry
Reason your way through it. I assume A2B is a solid. .........A2B --> 2A^+ + B^2- .....4.35E-4M....x......x For every molecule of A2B that dissolves, you must have two (2) ions of A^+ and one (1) ion of B^2-; therefore, for every 4.35E-4 mols A2B that dissolve, you must ...
Sunday, March 16, 2014 at 8:43pm

Chemistry
I have discovered a new chemical compound with the formula A2B. If a saturated solution of A2B has a concentration of 4.35x10-4M. a) What is the concentration of B2- ions? b. What is the concentration of A1+ ions? c. What is the solubility product constant for A2B? Can you ...
Sunday, March 16, 2014 at 8:31pm

chemistry
There must be a question in here somewhere.
Sunday, March 16, 2014 at 8:12pm

chemistry
Upon decomposition, one sample of magnesium fluoride produced 1.95 kg of magnesium and 3.05 kg of fluorine. A second sample produced 1.10 kg of magnesium.
Sunday, March 16, 2014 at 8:00pm

Chemistry 151
Use the dilution formula for these. c1v1 = c2v2 c = concn v = volume for a. 100 mL x 0.1M = ? mL x 1M Solve for ?mL of the 1M. b. 250 mL x 0.5M = ? mL x 1 M Solve for ?mL of 1 M.
Sunday, March 16, 2014 at 7:06pm

Chemistry
6.44% by mass means 6.44 g glucose/100 g solution. What is the volume of the solution? That is mass = volume x density. You know d and you know mass; solve for volume in mL and convert to L. Then find mols solute. That is 6.44g/molar mass glucose. Finally, M = mols/L solution...
Sunday, March 16, 2014 at 7:03pm

Chemistry
Actually it makes little difference which we call the solute and which the solvent; however, usually we assign the solute to the smaller quantity and the solvent to the larger number. Or if solid/liquid, we usually call the solute the solid and the solvent the liquid. In the ...
Sunday, March 16, 2014 at 7:01pm

Chemistry
I get close to that answer if we neglect the fact that an extra electron produced is ignored, AND I think you transposed numbers for the mass of the proton. I think (2.0141 - 2*1.00728) = ? amu Change to kg. ?amu x (1/6.022E23*1000) = kg E = kg*c^2 and that gives me 6.86E-14 ...
Sunday, March 16, 2014 at 6:27pm

Chemistry
What is the percent by volume concentration of a solution containing 300.mL of isopropyl alcohol and enough water to give 400.ml of solution?Which component is the solute and which is the solvent?
Sunday, March 16, 2014 at 6:20pm

Chemistry
What is the molarity of an aqueous solution that is 6.44% glucose (C6H12O6) by mass? (Assume a density of 1.03 g/mL for the solution.)
Sunday, March 16, 2014 at 5:46pm

Chemistry 151
5) How many mL of 1M HCl is used to make the following dilutions? a) 100mL of 0.1M HCl = b) 250mL of 0.5M HCl= c) 10ml of 0.01M HCl= 36.64 is the molar mass of hcl do I divide that into ml?
Sunday, March 16, 2014 at 5:18pm

I don't get it--Chemistry

Sunday, March 16, 2014 at 5:04pm

chemistry
mol NH4NO3 = grams/molar mass Then M = mols/L solution. You know mols and L soln, solve for M.
Sunday, March 16, 2014 at 5:02pm

Chemistry
Thank you very much for your time on this and the other problems I posted. You are appreciated. Selina Olomua
Sunday, March 16, 2014 at 4:49pm

Chemistry
find the moles of silver nitrate: .02/formulamassAgNO3 then What is the volume of the solution? Well, the mass of silver nitrate is very small, so assume it is all water, 1kg=1liter Molarity=moles/1Liter
Sunday, March 16, 2014 at 4:48pm

Chemistry
Find the molarity of 0.02g of silver nitrate dissolved in 1kg of water
Sunday, March 16, 2014 at 4:44pm

Chemistry
These are limiting reagent problems. I solve these the long way. Starting with one of the reactants, calculate how much of one of the products will be formed. Do the same for the other reactant and the same product. If both answers are the same everything is in the right ...
Sunday, March 16, 2014 at 4:39pm

Chemistry
Thank you so much. I figured out what I did wrong.
Sunday, March 16, 2014 at 4:34pm

Chemistry
How many mols Cu(OH)2 do you need? That's mols = g/molar mass = 100/97.56 = approx 1 mol but you need to do it more accurately. Convert mols Cu(OH)2 to mols NaOH = twice that = about 2 mol (again, do it more accurately). M NaOH = mols/L. You know mols NaOH and M NaOH, ...
Sunday, March 16, 2014 at 4:22pm

Chemistry
3
Sunday, March 16, 2014 at 4:17pm

Chemistry
I think it's your math. I obtained the same equation as you and it looks ok to me. I went through the math and obtained two values for x of 0.0631 (which can't be right since 0.110-2x gives a negative number) and 0.0471. That value plugged back into Kp expression gives...
Sunday, March 16, 2014 at 4:15pm

Chemistry
2) Given the balanced reaction equation predict the moles of each product given the following reactants: AlCl3 + 3 NaHCO3 Al(OH)3 + 3 NaCl + 3 CO2 AlCl3 NaHCO3 Al(OH)3 NaCl 58.4 CO2 a 1 mol 1 mol ? ? b 1 mol 3 mol ? ? c 3 mol 1 mol ? ?
Sunday, March 16, 2014 at 3:53pm

Chemistry
2 NaOH + CuSO4  Na2SO4 + Cu(OH)2 100g of Cu(OH)2 is needed. Assuming 100% yield, how much of 1M NaOH and 0.5M CuSO4 must be used in mL?
Sunday, March 16, 2014 at 3:44pm

Chemistry
This is a problem I got on my Mastering Chemistry homework: Consider the following reaction: H2(g)+I2(g)⇌2HI(g) A reaction mixture at equilibrium at 175 K contains PH2=0.958atm, PI2=0.877atm, and PHI=0.020atm. A second reaction mixture, also at 175 K, contains PH2=PI2= 0...
Sunday, March 16, 2014 at 3:42pm

Chemistry
(1/A) - (1/Ao) = kt Substitute and solve for k. Second part. rate = delta A/delta T = -0.01/200
Sunday, March 16, 2014 at 2:39pm

chemistry
q = mass EtOH x specific heat EtOH x (Tfinal-Tinitial) Substitute and solve for Tf.
Sunday, March 16, 2014 at 2:24pm

chemistry
18.5 kPa
Sunday, March 16, 2014 at 1:52pm

chemistry
The specific heat of ethanol is 0.59 cal/g Celsius If one adds 450 cal of heat to 37 g of ethanol at 20 celsius what would the final temp be
Sunday, March 16, 2014 at 1:44pm

Chemistry
The net reaction for fusion on a star like our Sun is: 4H(1,1) ==> He(4,2) + 2e(0,+1) Calculate the mass defect for this reaction. If one atom of He is formed this way, calculate the energy released. If one Kg of He is formed, calculate the energy released. The masses of ...
Sunday, March 16, 2014 at 12:07pm

Chemistry
When the rate of the reaction 2NO+O2=2NO2 was studied, the rate was found to double when the O2 concentration alone was doubled but to quadruple when the NO concentration alone was doubled. Which of the following mechanisms accounts for these observations? a.) Step 1: NO + O2=...
Sunday, March 16, 2014 at 11:45am

Chemistry
Determine the rate constant for the following second-order reaction: A=C+2D given that the initial concentration of A is .3 M and that the concentration of C increase to .01 M in 200 seconds. Express the result in terms of the rate law for the loss of A.
Sunday, March 16, 2014 at 11:44am

chemistry
calculate the molarity of the solution prepared by dissolving 16.45g NH4NO3 in water to make 250.mL solution.
Sunday, March 16, 2014 at 8:39am

Chemistry
Alternative answers: A)10 B)13 C)1.9 D)3.8 E)12
Sunday, March 16, 2014 at 6:10am

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