Thursday
October 27, 2016

# Posts by Hannah

Total # Posts: 3,242

Which of the following equations correspond to the Ka2 for phosphoric acid? note: the double equal sign (==) means equilibrium. a) HPO42- (aq) + H2O (l) == H3O+(aq) + PO43-(aq) b) PO43- (aq) + H2O (l) == HPO42-(aq) + OH–(aq) c) H3PO4 (aq) + H2O (l) == H3O+(aq) + H2PO4-(aq...
April 1, 2012

What is the equilibrium constant for the reaction of ammonium ion with formate ion? I know that the ionization constant for ammonium ion is Ka=5.6e-10 and for formate Kb=5.6e-11. I am not sure what to do next. Should I divide ka by kb?
April 1, 2012

Chemistry
What is the equilibrium constant for the reaction of ammonium ion with formate ion? I know that the ionization constant for ammonium ion is Ka=5.6e-10 and for formate Kb=5.6e-11. I am not sure what to do next. Should I divide ka by kb?
April 1, 2012

is 2.5e-5 my answer or do I have to do another step?
April 1, 2012

so kb = 1.0e-14 / 4.0e-10 = 2.5e-5
April 1, 2012

is Kw 1.0e-14?
April 1, 2012

1) The Ka for acetic acid is 1.8e-5. What is the pH of a 3.18M solution of this acid? I did 1.8e-5 = x^2/3.18 x=sqrt 1.8e-5 X 3.18 = 7.56e-3 pH=-log(7.56e-3) = 2.12 The pH is 2.12 2) At 25 degrees celsius, the pH of a 1.75M NaCN solution (the Ka for HCN is 4.0e-10) is ? 4.0e-...
April 1, 2012

Life orientation
we will not just answer your homework questions. Give us some information to work with and then we can tell you if it is correct and add on to it
April 1, 2012

So the lowest pH would be the acidic solution correct?
April 1, 2012

Which 0.10M solution has the lowest pH? NaCl, KCN, LiF, RbClO, all have the same pH. I think that the answer is that they all have the same pH. Would you agree? Thank you!
April 1, 2012

Given the wage in dollar per day and the CPI for years 1 and 2 how do you calculate the nominal % increase in wage and the real % increase in wage? I am not sure what to do for this or what the formula is if any. Thank you for your help.
April 1, 2012

Chemistry(Please respond, thank you)
Oh ok I got it now thank you.
April 1, 2012

Chemistry(Please respond, thank you)
What is the [H3O+] for a neutral solution at 50 degrees celsius? I know that kw=[H3O+][OH-] but I am not sure what to do to get the H3O. The value I have for kw=5.76e-14 and I have the pH 6.62 but I do not know what the OH would be. Chemistry(Please help, thank you) - DrBob222...
April 1, 2012

I don't know if I put this in my calculator correctly but I got -0.82.
March 31, 2012

so I would take the - log of 6.62?
March 31, 2012

What is the [H3O+] for a neutral solution at 50 degrees celsius? I know that kw=[H3O+][OH-] but I am not sure what to do to get the H3O. The value I have for kw=5.76e-14 and I have the pH 6.62 but I do not know what the OH would be.
March 31, 2012

Given the wage in dollar per day and the CPI for years 1 and 2 how do you calculate the nominal % increase in wage and the real % increase in wage? I am not sure what to do for this or what the formula is if any. Thank you for your help.
March 31, 2012

Economics(Please respond, thank you)
Given the wage in dollar per day and the CPI for years 1 and 2 how do you calculate the nominal % increase in wage and the real % increase in wage? I am not sure what to do for this or what the formula is if any. Thank you for your help.
March 30, 2012

Chemistry(Please check, thank you)
For an experiment on the effect of a buffer solution, I need to calculate the expected pH of the buffer. I know that I have to make an amounts table and use the Hasselbalch equation to find the pH. For the first part, 0.10M HCl was added to a buffer. The first addition was 5 ...
March 29, 2012

Organic Chemistry
I'm looking for a site with all the pentene isomers, and all the pentyne isomers. Anyone got any suggestions?
March 26, 2012

Chemistry
a) Write the chemical formula for the simplest pentyne isomer, b) give the name of the two isomers that have pentyne as the base chain, c) give the name of the one isomer that has butyne as the base chain, d) give the name of the 5 chain cyclic isomer, e) give the name of the ...
March 26, 2012

Chemistry
4 a) Write the chemical formula for the simplest pentene isomer, b) give the name of the two isomers that have pentene as the base chain, c) give the name of the three isomers that have butene as the base chain, d) give the name of the 5 chain cyclic isomer, e) give the name ...
March 26, 2012

Math
Mark wanted to measure the height of a nearby building. He placed a mirror on the pavement at point P, 80 feet from the base of the building. He then backed away until he saw an image on the top of the building in the mirror. If Mark is 6 feet tall, and he is standing 9 feet ...
March 26, 2012

Math
(4.44e-2 - x) (8.06e-2 - x) / (0.331 + 2x)^2 = 1.80e-2 I need to rearrange this equation so that I can get a,b, and c, for the quadratic equation but I am not sure how to do this. Thank you for the help. Math(Please answer, thank you) - bobpursley, Sunday, March 25, 2012 at 7:...
March 25, 2012

So I have to multiply (4.44e-2 -x )(8.06e-2 - x) by (0.331 + 2x)^2 or am I suppose to multiply 1.80e-2 by it?
March 24, 2012

(4.44e-2 - x) (8.06e-2 - x) / (0.331 + 2x)^2 = 1.80e-2 I need to rearrange this equation so that I can get a,b, and c, for the quadratic equation but I am not sure how to do this. Thank you for the help.
March 24, 2012

Chemistry
Determine the concentration in parts per million if 0.500 moles of NaCl are found in 35000g of a salt water solution. Okay, so I've done questions dealing with ppm and was able to work them out fine, but I can't seem to figure this one out. Any help you can give me ...
March 24, 2012

Ok so the only one im still not sure about is CO3^2-^. The -2 are lone pairs so I guess it is both Lewis and BL.
March 24, 2012

Oh Im sorry I missed that. CO3^2-^ is an answer listed. I was able to find that CN^-^ is a BL base but Im still not sure if it is a Lewis base. I do not think it is.
March 24, 2012

1) Which statement below is correct (true)? a) Since HNO2 is a stronger acid than HF it must have a greater pKa. b) Since HOCℓ is a stronger acid than HCN, then OCℓ– is a stronger base than CN–. c) The dissociation (or ionization) of HOCℓ in water ...
March 24, 2012

1) Which of the following is not amphiprotic? H20, NH4^+^, HSO4^-^, H2PO4^-^, all choices are amphiprotic. I think that all of these are amphiprotic. I know for sure that H20 and H2PO4^-^ are. 2) The ion HPO4^-^ has both a conjugate base as well as a conjugate acid. The ...
March 24, 2012

Chemistry(Please just check, thank you)
1) The approximate pH of a 3.0 X 10^-3 M solution of the strong acid H2SO4 is? I did pH= -log(3.0 X 10^-3) = 2.5 2)If HCLO2 is a stronger acid than HF, which is stronger than HOCL, then the order of strengths of the conjugate bases of these acids is? My answer is CLO2^-^ < ...
March 24, 2012

Chemistry
Write the chemical formula for the simplest heptane isomer and give its name, b) give the names of two heptane isomers with hexane as the base chain, c) give the names of names of the five heptane isomers with pentane as the base chain, d) give the name of the isomer with ...
March 24, 2012

Chemistry
What is the mass in kg of 20.0 L of diesel fuel? Assume the fuel has a density of 0.85 g/mL.
March 24, 2012

media
d. wire services
March 21, 2012

Chemistry
Thank you very much!
March 21, 2012

Chemistry
Consider the reaction: PCl3(g) + Cl2(g) PCl5(g). If [PCl3] = 0.78 M, [Cl2] = 0.44 M, and [PCl5] = 0.88 at equilibrium, what is the value of K? A.0.39 B.1.4 C.2.6 D.0.72 Thanks!
March 21, 2012

For an experiment we had to test the equilibrium of BiCl3 - BiOCl First I had to mix a small amount of BiCl3 with 2mL of water. After doing this the color was cloudy white. Then I added6.0M of HCl drop-wise in which the color became clear. Then 25mL was added and the color ...
March 20, 2012

statistics
The average score on a science test was 72 with a standard deviation of 6. The average score on a history test was 89 with a standard deviation of 7. Compare the variability of the two classes.
March 20, 2012

Chemistry(Please respond, thank you)
I think that's why Im so confused because when added the HCl it only turned dark yellow and then our tube with the NaOH didn't even change. Ok so I see why it would shift to the left but im not sure what it was reacting with. From the equation the CrO4^2-^ is on the ...
March 20, 2012

Chemistry(Please respond, thank you)
oh ok I have to include in my answer if the process is exo or endothermic but I am not sure how I am suppose to know that. We then had to add 1 drop of 1.0M NaOh to a new test tube with 2.5mL of Na2CrO4 in it. I guess the color change was suppose to be orange even though my ...
March 20, 2012

Chemistry(Please respond, thank you)
Also the next question was which chromium ion is orange and which is yellow ans how do you know. So the dichromate is yellow and the Cr207^2-^ is yellow correct??
March 20, 2012

Chemistry(Please respond, thank you)
Ok so when the HCl is added it shifts to the right which is an exothermic process correct? It shifted to the right because the reactant is being used up??
March 20, 2012

Chemistry(Please respond, thank you)
For an experiment I had to add 1 drop of 1.0M HCl into a test tube that had 2.5mL of 0.10M Na2CrO4 and record the color. The original color of the Na2CrO4 was yellow. After adding the HCl the color became a very dark yellow. I know that the equilibrium shifted shifted to the ...
March 20, 2012

Algebra 2
Factor 12^2-3
March 19, 2012

chemistry
In the 1970s, when lead was widely used in "ethyl" gasoline, the blood level of the average American contained 0.25 ppm lead. The danger level of lead poisoning is 0.80 ppm. (a) What percent of the average person was lead? (b) How much lead would be in an average 80 ...
March 19, 2012

thank you for your help
March 18, 2012

2.5 X 10^(-3) = (.28)(.38) / x^2 Solve for x. 2.5 X 10^(-3) = 0.1064 / x^2 2.5 X 10^(-3) X 0.1064 = 266 sqrt 266 = 16.3 Did I do this correctly?? Thank you for your help.
March 18, 2012

Math(Please someone respond, very confused)
ok thank you!!!
March 18, 2012

Math(Please someone respond, very confused)
thank you I was looking for that post but couldn't find it.
March 18, 2012

Math(Please someone respond, very confused)
The original equation was 1.7e-3 = (0.0015 -x)^2 / (0.025 +1/2x)(0.025 + 1/2x) Square root of both sides is 0.0412 = (0.0015-x) / (0.025 + 1/2x) Solve for x and when I put in -0.001 or 1.0e-3 it says that it is incorrect, I don't know why??
March 18, 2012

Math(Please respond, thank you)
yes , it is 10^(-3). I sorry,im just so confused. I am typing it exactly as it is shown on my homework. They used().
March 18, 2012

Math(Please respond, thank you)
The equation is written as 1.7e-3 = (0.0015-x)^2 / (0.025 + 1/2x)(0.025 + 1/2x)
March 18, 2012

Math(Please respond, thank you)
The original equation was 1.7e-3 = (0.0015 -x)^2 / (0.025 +1/2x)(0.025 + 1/2x) Square root of both sides is 0.0412 = (0.0015-x) / (0.025 + 1/2x) Solve for x and when I put in -0.001 or 1.0e-3 it says that it is incorrect, I don't know why??
March 18, 2012

The table below shows the market basket quantities and prices for the base year (year 1) Base year 1 Price in price Quantity base year yr 2 Product Pizza 15 \$3 \$3.75 t-shirts 4 \$10 \$9 rent 1 \$500 \$550 In year 1 the CPI was? In year 2 the CPI was? I know that cpi= (expenditures...
March 18, 2012

Economics(Please respond, thank you)
The table below shows the market basket quantities and prices for the base year (year 1) Base year 1 Price in price Quantity base year yr 2 Product Pizza 15 \$3 \$3.75 t-shirts 4 \$10 \$9 rent 1 \$500 \$550 In year 1 the CPI was? In year 2 the CPI was? I know that cpi= (expenditures...
March 18, 2012

Chemistry
Pure water boils at 100ºC (212ºF). When a substance is added to the water the boiling point increases due to what is referred to as the boiling point elevation. (a) What is the molecular mass of sucrose (C₁₂H₂₂O₁₁)? (b) If you add ...
March 18, 2012

The original equation was 1.7e-3 = (0.0015 -x)^2 / (0.025 +1/2x)(0.025 + 1/2x) Square root of both sides is 0.0412 = (0.0015-x) / (0.025 + 1/2x) Solve for x and when I put in -0.001 or 1.0e-3 it says that it is incorrect, I don't know why??
March 18, 2012

ok I tryed that to and for some reason it still says its wrong
March 18, 2012

yes its .0015 im sorry for the mistake, so it would be .0397=-40x +.5??
March 18, 2012

How did you get 39.5x?
March 18, 2012

For soem reason when I enter this answer on my online homework it says that its incorrect, I don't know why.
March 18, 2012

do for x I got 6.63e-4. Would you agree? Thank you for your help!!
March 18, 2012

oh ok and you got .0262 by subtracting 0.015 from 0.0412??
March 18, 2012

where did you get the 40x from??
March 18, 2012

0.0412 = 0.0015 - x / 0.025 + 1/2x Solve for x. 0.0412 = 0.015-x / 0.525x I am not sure where to go from here since there are two x's.
March 18, 2012

political science/media
d. wire services
March 16, 2012

Chemistry(Please respond, 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) So I understand that 2NO + Cl2 + 1/2O2 = NO2 + 1/2 Cl2 but I do not ...
March 15, 2012

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 15, 2012

Chemistry(Please respond, thank you!)
ok so 6.66(473K)(0.08206) = 258.5 which would be 2.59 which is one of the answer choices. Does this seem correct??
March 15, 2012

Chemistry(Please respond, thank you!)
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. Chemistry...
March 15, 2012

Chemistry - Please Check!
Thank you.
March 14, 2012

Chemistry - Please Check!
mZnS = 0.018 x 97.47 g/mol mZnS = 1.71 g I am pretty positive the first part of is right but, if my final answer is wrong again, could you explain the question for me?
March 14, 2012

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

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

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

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

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

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

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

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

So am I suppose to use the Kc values that are given??
March 14, 2012

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

I do not understand why do you 1/54.9??
March 14, 2012

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!!)
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. that's what i'm asking you
March 13, 2012

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

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

Thank you!!!
March 11, 2012

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 didn't get 6.31e-4. Where did I mess up???
March 11, 2012

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