Wednesday
September 17, 2014

Posts by Hannah


Total # Posts: 2,851

Chemistry - Please Check!
Determine the mass of zinc sulphide, ZnS, produced when 6.2g of zinc and 4.5g of sulphur are reacted. Equation given: Zn + S8 >> ZnS Balanced equation: 8Zn + S8 >> 8ZnS nZn= 6.2 g/ (65.39 g/mol) = 0.095 mol nS8= 4.5 g/(256.48 g/mol) = 0.018 mol nS8 = 0.095 mol Zn x...
March 14, 2012

Chemistry(Please respond)
Well Na ions were added so would that still shift to the left? How do you know if it's endo or exothermic I have to include that in my answer?
March 14, 2012

Chemistry(Please respond)
I did an experiment to study the effects of changes in conditions on an equilibrium system. The first system was the dissociation of acetic acid. HC2H3O2 -> H^+^ + C2H3O2^-^ <- We had to add 2mL of acetic acid into a test tube and we had to test the pH of the solution ...
March 14, 2012

Chemistry(Please help)
For the reaction, 2 SO2(g) + O2(g) == 2 SO3(g), at 450.0 K (Kelvin) the equilibrium constant, Kc, has a value of 4.62. A system was charged to give these initial concentrations, (SO3) = 0.254 M and (O2) = 0.00855 M, and (SO2) = 0.500 M. In which direction will it go? I think I...
March 14, 2012

Chemistry(Please help)
So I did 1/0.150 and got 6.66 so now I use this with RT. I am not sure what R is?
March 14, 2012

Chemistry(Please help)
For the system CaO(s) + CO2(g) = CaCO3(s), I added 1.00 mol of CaO(s) to 1.00L of 0.500M CO2(g) at 200 oC. At equilibrium the [CO2] = 0.150M. What is the value of Kp for this reaction? Kp would = CaCO3/(CaO)(CO2) I do not know what to do with the 0.500M and 1.00mol.
March 14, 2012

Chemistry(Please help, thank you!)
I am familiar with how to do the ICE table but I am not sure how to set one up for this question with the 2.5 moles.
March 14, 2012

Chemistry(Please help, thank you!)
A study of the system, H2(g) + I2(g) == 2 HI(g), was carried out. Kc = 54.9 at 699.0 K (Kelvin) for this reaction. A system was charged with 2.50 moles of HI in a 5.00 liter vessel as the only component initially. The system was brought up to 699.0 K and allowed to reach ...
March 14, 2012

Chemistry(Please help, thank you!)
So am I suppose to use the Kc values that are given??
March 14, 2012

Chemistry(Please help, thank you!)
Using this data, 2 NO(g) + Cl2(g) == 2 NOCl(g) Kc = 3.20 X 10-3 NO2(g) == NO(g) + ½ O2(g) Kc = 3.93 calculate a value for Kc for the reaction, NOCl (g) + ½ O2 (g) == NO2 (g) + ½ Cl2 (g) I do not understnad how I am suppose to use the Kc values given if ...
March 14, 2012

Chemistry(Please check answer)
I do not understand why do you 1/54.9??
March 14, 2012

Chemistry(Please check answer)
The equilibrium constant for the reaction, H2(g) + I2(g) == 2 HI(g) is 54.9 at 699.0 K (Kelvin). What is the equilibrium constant for 4 HI(g) == 2 H2(g) + 2 I2(g) under the same conditions? Note: the == indicates the equilibrium double arrow Since the second equation is ...
March 14, 2012

Chemistry(Urgent, please respond, thanks!!)
Thank you!!
March 14, 2012

Chemistry(Urgent, please respond, thanks!!)
1) For the reaction system, 2 SO2(g) + O2(g) = 2 SO3(g), Kc has a value of 4.62 at 450.0 K (Kelvin). A system, at equilibrium has the following concentrations: (SO3) = 0.254 M; (O2) = 0.00855 M. What is the equilibrium concentration of SO2? Is set this up as 4.62=(SO3)^2 / (...
March 14, 2012

math
i don't know. thats what i'm asking you
March 13, 2012

Astronomy
what are the largest stars in the HR diagram called?
March 13, 2012

Chemistry(Can someone please answer!!)
The decomposition of hydrogen peroxide in the presence of potassium iodide is believed to occur by the following mechanism: step 1 slow: H2O2 + I^- = H2O + OI^- step 2 fast: H2O2 + OI^- = H2O + O2 + I^- 1) What is the equation for the overall reaction? Use the smallest ...
March 11, 2012

Math(Can someone please answer!!)
Thank you!!!
March 11, 2012

Math(Can someone please answer!!)
ln [2.30E-2] = ln(0.102) - (k s-1)(2360 s) k = 6.31E-4 s -1 I did 2360k = 1n(0.102 * 0.023) 2360k = -6.055 then I divided 2360 by -6.055 but I didnt get 6.31e-4. Where did I mess up???
March 11, 2012

Math(Can someone please answer!!)
n [1.70E-2] = ln(0.144) - (k s-1)(3609 s) Solve for k. I have a TI30 calculator. Am I suppose to press just the ln button or do I have to press 2nd and then ln??
March 11, 2012

Math
ln [1.70E-2] = ln(0.144) - (k s-1)(3609 s) Solve for k. I have a TI30 calculator. Am I suppose to press just the ln button or do I have to press 2nd and then ln??
March 11, 2012

Chemistry
The decomposition of hydrogen peroxide in the presence of potassium iodide is believed to occur by the following mechanism: step 1 slow: H2O2 + I^- = H2O + OI^- step 2 fast: H2O2 + OI^- = H2O + O2 + I^- 1) What is the equation for the overall reaction? Use the smallest ...
March 11, 2012

Chemistry
The decomposition of hydrogen peroxide in the presence of potassium iodide is believed to occur by the following mechanism: step 1 slow: H2O2 + I^- = H2O + OI^- step 2 fast: H2O2 + OI^- = H2O + O2 + I^- 1) What is the equation for the overall reaction? Use the smallest ...
March 10, 2012

Chemistry
1/[N2O] = 1/(1.75M) + (1.10E-3M^-1 S^-1)(1852s) [N2O] = 0.383 M I know I posted a similar question but I am having trouble with this one as well. Should I do 1/1.75 first and then add 1.10e-3 and then multiply by 1852? Math(Thank you for your help) - john, Friday, March 9, ...
March 9, 2012

Chemistry(Please help explain)
The decomposition of hydrogen peroxide in the presence of potassium iodide is believed to occur by the following mechanism: step 1 slow: H2O2 + I^- = H2O + OI^- step 2 fast: H2O2 + OI^- = H2O + O2 + I^- 1) What is the equation for the overall reaction? Use the smallest integer...
March 9, 2012

Chemistry(Urgent, please answer)
Disregard question. I figured it out!
March 9, 2012

Chemistry(Urgent, please answer)
If you are given the slope and y intercept how do you find the rate constant of a chemical equation??? Would I multiply the slope and the y intercept???
March 9, 2012

Math(Thank you for your help)
So first I did multiplication (1.10e-3)(1852) and then divided 1/1.75 and then added and I cant get the answer.
March 9, 2012

Math(Thank you for your help)
1/[N2O] = 1/(1.75M) + (1.10E-3M^-1 S^-1)(1852s) [N2O] = 0.383 M I know I posted a similar question but I am having trouble with this one as well. Should I do 1/1.75 first and then add 1.10e-3 and then multiply by 1852?
March 9, 2012

Chemistry(Thank you for your help!)
O ok I didnt know it was that easy!!! Thank you!
March 9, 2012

Chemistry(Thank you for your help!)
The following info was obtained: [HI], M 0.535 0.268 0.134 6.70E-2 seconds 0 520 781 911 What is the average rate of disappearance of HI from t = 0 s to t = 520 s The answer is 5.13E-4 M s-1 but I do not understand how to get this!!!Could someone please explain!! Thank you!!
March 9, 2012

Math(Please, please help)
1/[N2O] = 1/(1.75M) + (1.10E-3M^-1 S^-1)(1852s) [N2O] = 0.383 M I know I posted a similar question but I am having trouble with this one as well. Should I do 1/1.75 first and then add 1.10e-3 and then multiply by 1852?
March 9, 2012

Math(Please answer just a quick question!!!!)
Ok how did you get 5.56e-3???
March 8, 2012

Math(Please answer just a quick question!!!!)
If the time elapsed is 4.26 min, what is the value of the rate constant, k? ln[R]t / [R]o = -0.0237 I am not sure how to slove this. Would I do ln 4.26 minutes times -0.0237???
March 8, 2012

Math(Please help)
ok thank you so much!!!
March 8, 2012

Math(Please help)
ln [5.01E-3] = ln(4.86E-2) - (1.80E-2s-1)(t s) Solve for t. t = 126 s First I did 4.86e-2 - 1.80e-2 and then on my calculator I pressed the 2nd button and then ln and got 1.031. Then I did the same thing to get the ln of 5.01e-3 and divided that by 1.031 but did not get 126 as...
March 8, 2012

Math
yes thats what it means and how I posted it is exactly how it is written on my homework but I just cant seem to get that answer.
March 8, 2012

Math
ln [5.01E-3] = ln(4.86E-2) - (1.80E-2s-1)(t s) Solve for t. t = 126 s First I did 4.86e-2 - 1.80e-2 and then on my calculator I pressed the 2nd button and then ln and got 1.031. Then I did the same thing to get the ln of 5.01e-3 and divided that by 1.031 but did not get 126 as...
March 8, 2012

Math
If the time elapsed is 4.26 min, what is the value of the rate constant, k? ln[R]t / [R]o = -0.0237 I am not sure how to slove this. Would I do ln 4.26 min X -0.0237?
March 8, 2012

Chemistry(Please, please help)
If the time elapsed is 4.26 min, what is the value of the rate constant, k? ln[R]t / [R]o = -0.0237 I am not sure how to slove this. Is Rt 4.26 min
March 7, 2012

Chemistry (stoichiometry)
18.5 grams of calcium chloride reacts with 25.7 grams of sodium phosphate and produces calcium phosphate and sodium chloride. What is the limiting reactant? (show work)
March 7, 2012

Chemistry(Please help, thank you!)
If the time elapsed is 4.26 min, what is the value of the rate constant, k? ln[R]t / [R]o = -0.0237 I am not sure how to slove this. Is Rt 4.26 min?
March 6, 2012

Chemistry
I need to calculate the valueof Kc for 5 test tubes for an experiment that I completed on determination of Kc. The equation used was Fe^3+ + SCN^-= FeSCN^2+ After creating an ice table for the first test tube my values for Fe and SCN were 6.5e-4M and for FeSCN I got 5.7e-5M. ...
March 6, 2012

Chemistry(Please check)
I need to calculate the valueof Kc for 5 test tubes for an experiment that I completed on determination of Kc. The equation used was Fe^3+ + SCN^-= FeSCN^2+ After creating an ice table for the first test tube my values for Fe and SCN were 6.5e-4M and for FeSCN I got 5.7e-5M. ...
March 6, 2012

Chemistry(Please help)
Nevermind I know what I did wrong. I had to divide my final answer by 1000 to get kJ.
March 6, 2012

Chemistry(Please help)
I did -1.23e4 / 8.314 = -1479.43 and I tryed 1.23e4 / 8.314 = 1479.43 but my online homework keeps saying that its incorrect.
March 6, 2012

Chemistry(Please help)
I had to make a graph using lnK vs 1/T adn find the slope. The slope was -1.23e4 and now I have to find Ea. Do I divide the slope by R
March 6, 2012

Chemistry
If the time elapsed is 4.26 min, what is the value of the rate constant, k? ln[R]t / [R]o = -0.0237 I am not sure how to slove this. Is Rt 4.26 min?
March 5, 2012

Chemistry
I had to make a graph using lnK vs 1/T adn find the slope. The slope was -1.23e4 and now I have to find Ea. Do I divide the slope by R?
March 5, 2012

Chemistry(Please check)
Right so for Fe I did (0.005M) (1.0mL Fe) / (7.0mL total of solutions in the tube) = 7.1e-4. So then my ICE table would say 7.10e-4 for both Fe and SCN because SCN for tube 1 had the same amounts and then I would subtract 7.1e-4 by the concentration of product which was 5.7e-5...
March 5, 2012

Chemistry(Please check)
Oh I see thats the total of SCN and Fe but we also used 0.1M HNO3 so for the first test time we used 5mL of HNO3 with the Fe, SCN so the total would be 7mL. Fe= (0.005M) (1.0mL) = x(7mL) = 0.000714 So 7.1 e-4 Correct. The teacher said to put the answer in 2 sig figs.
March 5, 2012

Chemistry(Please check)
Where did the 2mL come from?
March 5, 2012

Chemistry(Please check)
I think I know where I made a mistake. For the initial concentrations of reactants Fe and SCN it says that I can use the table that was provided to determine how much the total volume of each solution was used. The table that was provided provided the amount of Fe and SCN used...
March 5, 2012

Chemistry(Please check)
I completed a lab to find the determination of Kc. I have to find the concentrations of reactants at equilibrium using an ICE table. The equation that were are using is Fe^3+(aq) + SCN^-(aq) -> Fe(SCN)^2+(aq) I have to create 5 ICE tables because we used 5 different test ...
March 5, 2012

Calculus
Find the orthoganal trajectories of the family. Use a graphing utility to graph several members of each family. y = Ce^x What am I supposed to do here? Can someone point me in the right direction?
March 5, 2012

Chemistry
If the charge to mass ratio of a proton is 9.58 x 10^7 coulomb/kilogram and the charge is 1.60 x10^-19 coulomb, what is the mass of the proton?
March 4, 2012

Chemistry(Urgent, please check)
So besides the weird number I got I'm guessing that I set it up correctly.
March 4, 2012

Chemistry(Urgent, please check)
I put it in my calculator as 1.0 - 5.7 X e-5 and got 0.999943 I don't know why?
March 4, 2012

Chemistry(Urgent, please check)
I completed a lab to find the determination of Kc. I have to find the concentrations of reactants at equilibrium using an ICE table. The equation that were are using is Fe^3+(aq) + SCN^-(aq) -> Fe(SCN)^2+(aq) I have to create 5 ICE tables because we used 5 different test ...
March 4, 2012

Chemistry(Please check, thank you!)
I completed a lab to find the determination of Kc. I have to find the concentrations of reactants at equilibrium using an ICE table. The equation that were are using is Fe^3+(aq) + SCN^-(aq) -> Fe(SCN)^2+(aq) I have to create 5 ICE tables because we used 5 different test ...
March 4, 2012

Chemistry
so then 4.
March 3, 2012

Chemistry
To balance the equation would I add a 2 in front of the O2?
March 3, 2012

Chemistry
For the reaction system, 2 H2O(g) + O2(g) == 2 H2O2 (g), the equilibrium concentrations are (H2O2) = 0.120 M; (H2O) = 0.860 M; (O2) = 0.330 M. Calculate the value of Kc for this reaction. A. 0.423 B. 0.872 C. 0.0590 D. 1.31 E. 2.51 I did 0.120 / 0.860 X 0.330 = 4.4228 = 4.23...
March 3, 2012

Chemistry
The reaction, 2 SO3(g) == 2 SO2(g) + O2(g) is endothermic. Predict what will happen if the temperature is increased. A. the pressure decreases B. more SO3(g) is produced C. Kc increases D. Kc decreases E. none of the above I chose that Kc will increase. Would you agree?
March 3, 2012

Chemistry(Please check)
Oh wow I didnt even realize that they were both solids, I understand thank you!!
March 3, 2012

Chemistry(Please check)
The equilibrium constant, Kc for the system, CaO(s) + CO2(g) == CaCO3(s), is A. Kc = (CaO) (CO2) / (CaCO3) B. Kc = (CO2) C. Kc = (CaCO3)/(CaO) D. Kc = (CaCO3) / (CaO) (CO2) E. Kc = 1 / (CO2) My answer is (CaCo3) / (CaO)(CO2). Would you agree?
March 3, 2012

Chemistry(Please check)
For the reaction, 2 SO2(g) + O2(g) == 2 SO3(g), at 450.0 K (Kelvin) the equilibrium constant, Kc, has a value of 4.62. A system was charged to give these initial concentrations, (SO3) = 0.254 M and (O2) = 0.00855 M, and (SO2) = 0.500 M. In which direction will it go? A. to the...
March 3, 2012

Math
Disregard question. I figured it out. You take the ln of -2.035 and then multiply by 2.34 to get k2.
March 3, 2012

Math
ln k2/2.34 = -103,000J/8.314J/Kol[1/339K - 1/359K] ln k2/2.34 = -2.035941063 I am not sure what to do now!!
March 3, 2012

Chemistry(Please check answer)
For my online homework when I put the answer in it keeps saying its wrong and says k[reactant 1]^order1 [reactant 2]^order2 but I thought I did this.
March 3, 2012

Chemistry(Please check answer)
2NO(g) + Br2(g) -> 2NOBr(g) What is the rate equation? My answer is k[NO]2[Br2] Is this correct? Thank you!!!!
March 3, 2012

Chemistry(Please check)
ok thank you!!
March 3, 2012

Chemistry(Please check)
Ok so 0.0000572 = 5.7 X 10-5 M as the concentration ?
March 3, 2012

Chemistry(Please check)
I ahve to find the concentration of product, (Fe(SCN)^2+) at equilibrium. We have to use the equation k=A/C I have the value for k and A so my equation is 7917.6 = 0.453/C = 3586.67M Did I do the math correctly?
March 3, 2012

Chemistry
So the equation I use is ln k = a + (-ea/rt) correct?
February 29, 2012

Chemistry
A particular reaction has an activation energy of 51.6kJ/mol-rxn. How much faster is the reaction at 50 degrees C versus 25degrees C? I do not know how to start this!
February 29, 2012

Chemistry
He didnt say, he just posted the question like above.
February 29, 2012

Chemistry
Those were the values that the teacher put in there. I just assumed that since H2 and Br2 are -x and HBr is +2x that HBr would be 2 X 0.10..
February 29, 2012

Chemistry
I tryed and got .20. Is this correct?
February 29, 2012

Chemistry
For H2(g) + Br2(g) -> 2HBr(g) k=64 <- Ice table: H2 Br2 HBr I 0.10 0.10 0 C -x -x +2x E Solve for HBr at equilibrium I do not know how to start this.
February 29, 2012

Chemistry(Urgent, please check!!!)
The equation A + 2 B = C + D describes an elementary reaction, which takes place in a single step. Thus, the rate law must be? My answer is k(A)(B)^2 Is this correct?
February 29, 2012

Chemistry(Please check)
If the reaction Cl2 (g) + O3 (g) = Cl2O (g) + O2 (g) occurred in just two steps, what would be the overall order of the reaction be? a. 1 b. 2 c. 3 d. 4 e. not possible to determine from the information given I chose 2 as the answer. Is this correct?
February 29, 2012

Chemistry
I posted a question like this but my numbers were actually wrong. These are the correct ones. 5.94e-3 / 1.11e-3 = 5.33e-2/2.66e-2 5.35 = 2.00^m I guess this is not correct because I do not know a whole number that will give you 5.35. Chemistry - DrBob222, Tuesday, February 28...
February 28, 2012

Chemistry
Im pretty sure the concentrations that I obtained for the 5 flasks used are correct im just not sure I calculated the rate for each correctly. I was suppose to use the number of moles of I2 produced/L*min. For my I2 I got 6.66e-3 which was half of the S2O3^2- value which was 3...
February 28, 2012

Chemistry
It says to round the calculated p,q or z values to the nearest integer so that would be 5. Do you think that my numbers for M or rate are just incorrect?
February 28, 2012

Chemistry
I posted a question like this but my numbers were actually wrong. These are the correct ones. 5.94e-3 / 1.11e-3 = 5.33e-2/2.66e-2 5.35 = 2.00^m I guess this is not correct because I do not know a whole number that will give you 5.35.
February 28, 2012

Chemistry(Please, please help)
Disregard question.
February 28, 2012

Chemistry(Please, please help)
I need to find the order of a reaction with respect to the reactants. I set up my equation like this: 5.33e-2 M / 2.66e-2M = 1.03e-2 / 1.93e-3 I did the concentrations equal to the rates. I am just not sure what the units for rate should be. 2.00 = 5.33^m Did I set this up ...
February 28, 2012

Chemistry(Urgent, please help)
Diregard question.
February 28, 2012

Chemistry(Urgent, please help)
I need to find the order of a reaction with respect to the reactants. I set up my equation like this: 5.33e-2 M / 2.66e-2M = 1.03e-2 / 1.93e-3 I did the concentrations equal to the rates. I am just not sure what the units for rate should be. 2.00 = 5.33^m Did I set this up ...
February 28, 2012

Chemistry(Please check, thank you!!)
For my rate of reaction experiment I have to answer the question "why did we ask you to measure the room termperature and temperature of reaction solutions". For the experiment we used 5 flasks and we put one of them in an ice bath at 6-10 degrees C. My answer is ...
February 28, 2012

Math
1 mintue 25 seconds converted into seconds. I know there are 60 minutes in an hour and seconds 60 in a minute. Am I just dividing by 60??
February 28, 2012

Chemistry(please help)
I have to calculate the concentration of I2 produced (# of moles of I2 produced / L) based on the stoichiometric ratio in the following equation. 2S2O3^2- + I2 -> 2I^- + S4O6^2- So I got 6.6e-3 L*min for the amount of I2 produced. Now I have to calculate the rate for each ...
February 28, 2012

Chemistry(Please help, thank you)
So I got 6.6e-3 L*min for the amount of I2 produced. Now I have to calculate the rate for each of the 5 flasks used, so is the answer going to be the same for all 5?? It says to calculate the rate of reaction for each run using # of moles of I2 produced/L*min as the unit.
February 27, 2012

Chemistry(Please help, thank you)
Sorry I actually got 0.00666 so it would be 6.6e-3 correct?
February 27, 2012

Chemistry(Please help, thank you)
So the answer would be 6.66e-2 L*min? Is that the correct unit?
February 27, 2012

Chemistry(Please help, thank you)
So to find the amount of I2 produced as I first posted, it would be 1/2 that of 3.33e-3 correct? So 0.0666? Sorry, its important that I understand this correct
February 27, 2012

Chemistry(Please help, thank you)
Is L just the unit? Moles would be 3.33e-3M / L ?
February 27, 2012

Chemistry(Please help, thank you)
I have to calculate the concentration of I2 produced (# of moles of I2 produced / L) based on the stoichiometric ratio in the following equation. 2S2O3^2- + I2 -> 2I^- + S4O6^2- Chemistry(Urgent, please help) - DrBob222, Sunday, February 26, 2012 at 9:47pm If you know the ...
February 27, 2012

Math(Please check)
So are you saying thats not the answer????
February 27, 2012

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