Wednesday
November 26, 2014

Posts by Hannah


Total # Posts: 2,909

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

principles of physics
outside the earth, but within the orbital path of the moons.
March 2, 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

Math(Please check)
I got 0.011666667 so for correct sig figs is that 1.16e-2 or 1.1e-2?
February 27, 2012

Math(Please check)
What about (0.50)(1.75) = c2(75.00) c2=1.16e-2. Is this correct in terms of correct number of sig figs?
February 27, 2012

Math(Please check)
(0.50M)(3.50mL) = c2(75.00) c2= 2.3e-2 Is this correct?
February 27, 2012

Physics
How many seconds will elapse between seeing lightning and hearing the thunder if the lightning strikes 2 mi away and hte temperature is 100 degree F?
February 27, 2012

Physics
A ball is dropped from 27.0 ft above the ground. (a) Using energy considerations only, what is the velocity of the ball just prior to it hitting the ground? (b) If the ball is thrown back up to a ledge 15 m above the ground, what would be the velocity just as it reaches the ...
February 27, 2012

AB Calculus
So I'm supposed to verify the solution of the differential equation. The solution is y=e^(-x). The differential equation is 3y' + 4y = e^(-x). What is the problem asking me to do here?
February 27, 2012

algebra
f(x) = .70x You are taking 30% off, and 100%-30% is 70%. So you just multiply x (which is the original price marked on the item) by .70. So the shoes would be 65(.70) the slacks would be 48(.70) and the belt would be 15.50(.70)
February 27, 2012

Chemistry(Please check)
Ok so the answer is just 5.33? For an equation like this (0.50M)(1.75mL)= C2(75.00mL) would the answer just be 1.16e-3 or 1.16?
February 26, 2012

Chemistry(Please check)
(0.80M)(5.00mL) = c2 (75.00mL) c2 = 5.33e-2 M Is the correct amount of sig figs?
February 26, 2012

neuroscience
discuss spatial and temporal summation
February 26, 2012

Chemistry(Urgent, please help)
All I have is the concentration of S2O3^-2 which is 3.33e^-3M. How would I find moles? For the experiment we used 2.50mL of Na2S2O3. Do I use this to find moles?
February 26, 2012

Chemistry(Urgent, 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- Would the # produced be 2 for I2. I am not sure what to use for L?
February 26, 2012

Chemistry
(2.50mL)(0.10M) / 75.00mL = 0.003333 Im not sure how many sig figs to use. Would it 3.33e-3?
February 26, 2012

Chemistry(Please help)
I have to convert 1 minute 25 seconds into just seconds. Im not sure what to do. Thank you!!
February 26, 2012

Chemistry
It says that the final volume for every reaction solution is 75mL so is that what I divide by?
February 26, 2012

Chemistry
I had to perform an experiment for rate of reaction. The point of the experiment was to show how changes in reactant concentration, temperature, and catalyst presence can affect the rate of a reaction. The reaction that we studied was H2O2 + 2I^- + 2H^+ -> I2 + 2H2O We had...
February 26, 2012

Chemistry(Please check answers)
1) The decomposition of hydrogen peroxide in solution and in the presence of iodide ion was studied in laboratory, and the following mechanism proposed based on the experimental data. H2O2 + I - = H2O + IO - (slow) H2O2 + IO - = H2O + O2 + I - (fast) Which one of the ...
February 26, 2012

physics
what is the power of a 6 ohm bulb when 3 of such bulbs ar econnected in a 12 volt parallel circuit?
February 25, 2012

Chemistry(Please check)
1) The decomposition of hydrogen peroxide in solution and in the presence of iodide ion was studied in laboratory, and the following mechanism proposed based on the experimental data. H2O2 + I - = H2O + IO - (slow) H2O2 + IO - = H2O + O2 + I - (fast) Which one of the ...
February 25, 2012

Physics
What is the actual formula you are using? I cannot tell what you mean when you say "v=331.4 +0.6t". I want to actually learn how to do it.
February 25, 2012

Physics
how many seconds will elapse between seeing lightning and hearing the thunder if the lightning strikes miles away and the temperature is 100.0 degrees F?
February 25, 2012

Physics
A ball is dropped from 27.0 feet above the ground. Using energy considerations only, what is the velocity of the ball prior to it hitting the ground? If the ball is thrown back up to a ledge 15m above the groud, what would be the velocity as it reaches the ledge?
February 25, 2012

Chemistry(Please check)
1) The decomposition of hydrogen peroxide in solution and in the presence of iodide ion was studied in laboratory, and the following mechanism proposed based on the experimental data. H2O2 + I - = H2O + IO - (slow) H2O2 + IO - = H2O + O2 + I - (fast) Which one of the following...
February 25, 2012

Chemistry
Yes I think that helps me. Im not very good at this stuff so let me make sure I understand this. The concentration of the thiosulfate used was 0.10M and for each flask we used 2.50mL. So I have to multiply these two (2.50mL)(0.10M) and then divide by the total amount combined ...
February 25, 2012

Chemistry
I had to perform an experiment for rate of reaction. The point of the experiment was to show how changes in reactant concentration, temperature, and catalyst presence can affect the rate of a reaction. The reaction that we studied was H2O2 + 2I^- + 2H^+ -> I2 + 2H2O We had ...
February 25, 2012

Math
4x+y=-17 -3x+y=4 Please help me solve each system of equation and show your work.
February 25, 2012

Chemistry(Please check)
1) A catalyst alters the rate of a reaction by a. changing the products in the reaction. b. increasing the activation for the reaction. c. always providing a surface on which the molecules react. d. providing an alternate pathway for the reaction. e. increasing the ...
February 24, 2012

Chemistry(Please check)
1) The reaction: A + 3B = D + F was studied and the following mechanism was finally determined A+B=C (fast) C+B=D+E (slow) E+B=F (very fast) Which step has the largest activation energy? I chose the second step because it is slow and should have the most energy. Is this correct?
February 24, 2012

Chemistry
Im sorry. The point of the experiment was to show how changes in reactant concentration, temperature, and catalyst presence can affect the rate of a reaction. The reaction that we studied was H2O2 + 2I^- + 2H^+ -> I2 + 2H2O We had to set up 6 flasks each with and certain ...
February 24, 2012

Chemistry
I had to perform an experiment for rate of reaction. I have to calculate the concentration of Na2S2O3 in the reaction solutions based on the volume used in each reaction flask and the total volume calculated. There were five flasks used and for all 5 of them 2.50mL of Na2S2O3 ...
February 24, 2012

Chemistry
6.00 minutes 5 minutes 2 seconds 1 minute 32 seconds So 25.5 seconds / 60 = 0.4250. How can this be minutes?
February 24, 2012

Chemistry
I need to convert these 5 values of time into minutes. 1)1.07 1min 7 seconds 2) 6.00 3) 5.02 4) 1.32 5) 25.5 seconds The example that was given for conversion was 5 min 40 sec = 5.67min These are the values that I got after dividing by 60. 1) 1.07 = 1.12min 2) 6.00 = I didnt ...
February 24, 2012

ChemHelp
Chem Help! Limiting and excess reagent? Identify the limiting and excess reagent for each of the following scenarios involving the formation of silicone dioxide, SiO2. Please explain!!! Thank you! Si + O2 --> SiO2 a. 2 atoms of silicone and 2 molecules of oxygen gas b. 28.1...
February 23, 2012

Physical Science
Balance this equation: I2+HNO3 = HIO3+NO2+H2O
February 22, 2012

Chemistry(Urgent, please help,thank you)
oh ok I understand thank you so much for all of your help!!!
February 21, 2012

Chemistry(Urgent, please help,thank you)
After performing a freezing point depression experiment I had to find the molecular weight of glycol. Now I have to answer the question what value did I assume "i" to equal and why did I make this assumption. My teacher told us the value of i to use for this was 1. I...
February 21, 2012

Chemistry
I need to calculate the molecular mass of ehtylene glycol based on the freezing point depression. The teacher said that for glycol i=1 and to use the equation m=delta T / Kf X i Kf = -1.86C/m so I did -2.5C / -1.86 X 1 = 1.344 I know that 1.344 can't be the weight for ...
February 21, 2012

Chemistry
1) For a freezing point depression experiment we had to create an ice bath and add salt to the ice. I have to answer the question, why was salting the ice necessary in order to complete the experiment and how does this apply to the principles/concepts behind this experiment? ...
February 21, 2012

Physics
Suppose your power company charges $1.00 per kWh as its power rate. (a) What is the power in kW for an air conditioner that pulls 5 A on your standard 115 V household circuit? (b) How much does it cost you to run your air conditioner for 12 hours?
February 21, 2012

Physics
what is the voltage acros a 60.0 resistor with a current of 3 1/3 a?
February 21, 2012

Chemistry(Please help)
so for molality I got 1.344 then I did 1.344 = mols/0.10kg = 0.1344 Im not sure if I did this step right Then I did mm= g/mol 6.200 was the mass of the solute so mm=6.200 / 0.1344 = 46.13. I guess I made a mistake somewhere in my calculations because I thought that the mm of ...
February 20, 2012

Chemistry(Please help)
Disregard question I understand now. I have to solve for mols.
February 20, 2012

Chemistry(Please help)
the only info that I have is the mass of solute(g) and mass of solvent(kg) for glycol so im confused on what to use for mols?
February 20, 2012

Chemistry(Please help)
I need to calculate the molecular mass of ehtylene glycol based on the freezing point depression. The teacher said that for glycol i=1 and to use the equation m=delta T / Kf X i Kf = -1.86C/m so I did -2.5C / -1.86 X 1 = 1.344 I know that 1.344 can't be the weight for ...
February 20, 2012

Chemistry(Please help,thank you)
Nevermind, I made a mistake im sorry. Disregard the question.
February 20, 2012

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