Posts by hannah
Total # Posts: 3,483

Physics
Vector A has magnitude of 9.77 units and points due east. Vector B points due north. 1) What is magnitude of B, if the vector A+B points 34.7 north of east? 2) Find magnitude of A+B I am not sure what formulas to use for this. If someone could show me how to start this I will ... 
Physics(Please check)
Which equations are dimensionally correct? F=ma E=max X=(1/2)at^3 V=sqrt(2*fx/m) E=(1/2)mv I think that F=ma , E=(1/2)at^3, V=sqrt(2*fx/m) are correct. Would you agree? 
Physics(Please help)
thank you! 
Physics(Please help)
A force, F1 of magnitude 2.0N and directed due east is exerted on an object is F2=2.0N due north. What is the magnitude and direction of a third force, F3, which must be exerted on the object so that the resultant force is zero? I am not sure how to start this problem!! Thank ... 
Math
The circumference of the front tire is 6ft. How many complete turns does the front wheel make in 30 ft driveway? 
math
Compute: The number of combinations of 8 elements taken 3 at a time. The number of permutations of 8 elements taken 3 at at time. 
Physics(Please check)
I know the highest point would be 29.4 but I do not know how to get this. 
Physics(Please check)
Ok but where did the 9 come from? 
Physics(Please check)
1) How long does it take the ball to reach its highest point? I am not sure what I would divide 24 by to find this. 2) How high above the starting point is the highest point? I am not sure how to find this. 
Physics(Please check)
A 5kg ball is thrown straight up in the air with an initial speed of 24m/s. After its release and before it hits the ground when is the ball in free fall? My answer is at all times. Is this correct? Thank you. 
Physics(Please check thanks)
Thank you! 
Physics(Please check thanks)
Two vectors have magnitudes 4m and 3m. Which choice is not a possible magnitude for their resultant? 3m, 1m, 7m, 12m I chose 12m. Is this correct? 
Physics(Please respond)
why is sin negative? 
Physics(Please respond)
Vector A has a magnitude 2.4m and direction 130 degrees relative to the positive xaxis. Vector B has magnitude 3.0m and direction 250 degrees relative to the positive xaxis. 1) The resultant R=A+B has magnitude(in m) ? I know the R =2.75m but I am not sure how to get this. I... 
math
ok thank you! 
math
4 and 505/1000. but how does that help with this? 
math
calculate 10^1.27 how do i do this? 
Math
One bag contains 5 red marbles, 4 blue marbles, and 3 yellow marbles, and a second bag contains 4 red marbles, 6 blue marbles, and 5 yellow marbles. If Lydia randomly draws one marble from each bag, what is the probability that they are both not yellow? 
Chemistry
A patient with untreated diabetes may have a blood concentration of acetone of 20mg/100mL. Determine the molar mass of acetone and use this number to convert this concentration to mol/L. Okay, so I was able to determine the molar mass of acetone (= 58.09g/mol) however, i'm... 
physics
is increasing the current a valid method to increase the induced voltage when a magnet moves into a solenoid? 
Chemistry(Please help)
0.0885  x = 4.2e7 Then I added 0.0885 to the right side and got 8.85e2. Would this be the concentration or do I need to do another step? 
Chemistry(Please help)
Calculate the concentration of HCO3 in an aqueous solution of 0.0885 M carbonic acid, H2CO3 (aq). I was going to set this up as 0.0885 x = ? Am I suppose to use the Ka value for carbonic acid? 
Chemistry(Please respond)
I multiplied 0.119 by 1.58e10 and then took the square root, is that correct? 
Chemistry(Please respond)
I did 1.0e14 / 6.3e5 = 1.58e10 Then would I do (1.58e10)(0.119)? 
Chemistry(Please respond)
A 23.9 mL sample of 0.283 M trimethylamine, (CH3)3N, is titrated with 0.207 M hydrochloric acid. At the equivalence point, the pH is? I started off by doing 0.283 X 2.39e2 = 6.76e3 Then I did 6.76e3 / 0.207 = 3.36e2 2.39e2 + 3.36e2 = 5.65e2 6.76e3/5.65e2 = 0.119 I do ... 
surface area and volume
number 2 is wrong its b. 707 yd^2. 
Chemistry(Please help)
What is the molar solubility of barium phosphate in a 0.282M barium acetate solution? If I set up and ice table I would have 0.282M  X = ? Would I use the molar mass of barium acetate to complete the equation to find X? Ba3(PO4)2 ==> 3Ba^2+ + 2PO4^3 Ba(C2H3O2)2 ==> Ba^... 
Chemistry(Please help)
delta Go = 431.16kJ/mol  (298k X 0.12529 kJ/K*mol) I am having trouble converting the units for delta H and delta s to match. I multiplied delta H by 1000 to get kJ but this didn't give me the correct answer. Chemistry(Please help)  Dev, Wednesday, April 25, 2012 at 6:... 
Chemistry(Please check)
What is the molar solubility of barium phosphate in a 0.282M barium acetate solution? If I set up and ice table I would have 0.282M  X = ? Would I use the molar mass of barium acetate to complete the equation to find X? 
math
HELP PLEASE! I don't understand how to do the problem! Please help thanks(: The problem is: your bike tire has a radius of 14 inches. If your tire makes 100 revolutions, how many feet does your bike travel? THANKS! :D 
Chemistry(Please help)
I did 431.16kJ/mol X 1000 = 431160 Then 431160  (298 X 0.12529 kJ/K*mol) = 431197.33 for delta G but this answer was said to be incorrect, I do not know why?? 
Chemistry(Please help)
delta Go = 431.16kJ/mol  (298k X 0.12529 kJ/K*mol) I am having trouble converting the units for delta H and delta s to match. I multiplied delta H by 1000 to get kJ but this didn't give me the correct answer. 
Chemistry(Please help)
Now I do delta G = RT lnK So 17200 = 8.314(500) lnk 17200 = 4157 ln k This is where I am not sure what to do next do I add 4157 to the left side and then take the ln? 
Chemistry(Please help)
1) Nitrosyl chloride (NOCl) decomposes at high temperature. The equation is 2 NOCl (g) > 2 NO (g) + Cl2 (g) at 227oC Using delta Ho = 81.2 kJ and delta So = 128 J/K, calculate the value of the equilibrium constant for this reaction. I do not know how to start this problem... 
Chemistry(Please help)
So for delta G= delta H  T delta S it would be delta G= 81200 J/K  500K(128J/k) This would equal 17200. Did I do this correctly so far before I move on? 
Chemistry(Please help)
1) Nitrosyl chloride (NOCl) decomposes at high temperature. The equation is 2 NOCl (g) > 2 NO (g) + Cl2 (g) at 227oC Using delta Ho = 81.2 kJ and delta So = 128 J/K, calculate the value of the equilibrium constant for this reaction. I do not know how to start this problem ... 
Chemistry
I need to calculate the value of Kp at 25 degrees celsius using the delta Go value. Delta Go = 29.10kJ I know that Delta Go = RT lnK and that R=8.314e3kJ/K mol delta Go / RT I did 29.10 / 8.314e3 X 298K and 11.74 but this was wrong. I am stuck. What did I do wrong? 
Chemistry(Please check answers)
1) The standard molar entropy value of N2 (g) is 191.5 J/Kmol, of O2 (g) is 205.0 J/Kmol and of NO2 (g) is 240.0 J/Kmol. From these values we can calculate the Delta So for the reaction N2 (g) + 2 O2 (g)> 2 NO2 (g) to be? I did products  reactants (240 X 2)  [191.5... 
Chemistry(Please check answers)
For question 2 my actually chose that delta H is negative and delta s is positive I just typed the wrong answer in. Is this correct? 
Chemistry(Please check answers)
1) For a reaction delta Go is more negative than delta Ho. What does this mean? a. delta So is zero. b. delta So is negative c. delta So is positive d. delta So is negative if delta Ho is positive. e. delta So is negative if delta Ho is negative. I think that delta S is ... 
Chemistry
Thank you. 
Chemistry
Ok thank you the way you have it is exactly the way that it was stated on my homework. The only problem is that I realized that I had the typed the wrong number. It was suppose to be the same equation but with 2.49e1 instead 3.20e1. I understand everything except how did you... 
Chemistry
.50  x / x = 3.20e1 I need to solve for x. I was going to do .50 X 3.20e1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. Math(Please help)  Reiny, Tuesday, April 17, 2012 at 3:18pm You probably meant (.50  x)/x... 
Chemistry(Please check)
Thank you! 
Chemistry(Please check)
I think that 2NH3(g) > N2(g) + 3H2(g) is actually the other answer that is increasing because the number of moles increases from 2 to 4. So I chose answers 1 and 3. Is this correct? 
Chemistry(Please check)
Which of the following four processes are accompanied by an increase in entropy? 1. I2 (s) > I2 (g) 2. 2 I (g) > I2 (g) 3. 2 NH3 (g) > N2 (g) + 3 H2 (g) 4. Pb2+ (aq) + 2 OH – (aq) > Pb(OH)2 (s) Answers: a. 1 & 2 b. 1 & 3 c. 3 & 4 d. 2 & 4 e. only 3 I am ... 
Chemistry(Please check)
Now that I looked over this question again I agree with that too. Thank you! 
Chemistry(Please check)
Delta G^o for a reaction can be calculated from? 1. delta G^o f data 2. Delta H^o f and delta S data 3. equilibrium constants I chose that delta G can be calculated from H and S values. Would you agree? 
Chemistry(Please check)
1) Free energies of formation are a. always positive b. always negative c. never zero d. measured at 298K e. more than one response above is correct I think that free energies can be negative or postive so the answer cannot be e. I chose answer d, they are measured at 298K. ... 
Chemistry(Please check, thanks)
ok, the next question is which choice would have the next highest standard molar entropy. This would be liquid but since there are two liquids do I compare the molar masses? 
Chemistry(Please check, thanks)
I sorry I meant that CCl4(g) would be the highest since its a gas. 
Chemistry(Please check, thanks)
Which choice below has the highest standard molar entropy? SiCl4(s), CCl4(g), CCl4(l), Si(Cl4(l) I know that the gas state has the largest entropy so SiCl4(s) would have the highest. Is my answer correct? Thank you!! 
physics concept
Nevermind i was right 
physics concept
An astronaut who is floating freely through space is seated upon a unicycle. He begins to pedal the unicycle “forward.” As he does so,what would the astronauts' motion be in space? Would he rotate in the opposite direction of the spinning wheel? 
Economics(Please respond)
Given the increase in government expenditures and the marginal propensity to consume, how would you find the change in equilibrium GDP? I did the expenditures X the marginal propensity but this is wrong. 
language arts
i need help depicting a poem using literary terms. The poem is Dear Sister and goes: Do not believe what all you read in the papers, Leona, about the strikers being reds. It is true, the Communist Party of New York sent down a truckload of potatoes. You will find them rotted ... 
Chemistry(Please check)
.50  x / x = 3.20e1 I need to solve for x. I was going to do .50 X 3.20e1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. Math(Please help)  Reiny, Tuesday, April 17, 2012 at 3:18pm You probably meant (.50  x)/x = ... 
Chemistry(Please respond)
Step 1:H2O2 + I^^ = H2O + OI^^ step 2: H2O2 + OI^^ = H2O + O2 + I^^ What is the equation for the overall reaction? I am not sure how to do this since there are two equations. Complete the rate law for the overall reaction. I know how to do this one but I am not sure of ... 
Math(Please respond)
.50  x / x = 3.20e1 I need to solve for x. I was going to do .50 X 3.20e1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. Math(Please help)  Reiny, Tuesday, April 17, 2012 at 3:18pm You probably meant (.50  x)/x... 
Chemistry
Please disregard question. 
Chemistry
A 21.2mL sample of 0.307M ammonia, NH3 is titrated with 0.259 M hydrobromic acid. What is the pH before the addition of any hydrobromic acid? I am not sure how to start this. I know I could completeit if I knew where to start. Would I set up a moles table? 
Chemistry(Please respond)
Calculate the pH of an aqueous solution of 0.15 M potassium carbonate. I know that pH = log(H30+) but I am not sure how to start this problem. Chemistry(Please help)  DrBob222, Saturday, April 14, 2012 at 11:09pm Hydrolyze the CO3^2. CO3^ + HOH ==> HCO3^ + OH^ Do an ... 
Chemistry(Please respond, thank you)
Step 1:H2O2 + I^^ = H2O + OI^^ step 2: H2O2 + OI^^ = H2O + O2 + I^^ What is the equation for the overall reaction? I am not sure how to do this since there are two equations. Which species acts as a catalyst? I know that I^^ is the catalsyt. Which species acts as a ... 
Math(Please help)
.50  x / x = 3.20e1 I need to solve for x. I was going to do .50 X 3.20e1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. 
Chemistry(Thank you for your help)
Step 1:H2O2 + I^^ = H2O + OI^^ step 2: H2O2 + OI^^ = H2O + O2 + I^^ What is the equation for the overall reaction? I am not sure how to do this since there are two equations. Which species acts as a catalyst? I know that I^^ is the catalsyt. Which species acts as a ... 
Chemistry(Please help)
How do I set up an ice table when I only have .15M? 
Chemistry(Please help)
Calculate the pH of an aqueous solution of 0.15 M potassium carbonate. I know that pH = log(H30+) but I am not sure how to start this problem. Chemistry(Please help)  DrBob222, Saturday, April 14, 2012 at 11:09pm Hydrolyze the CO3^2. CO3^ + HOH ==> HCO3^ + OH^ Do an ... 
History, World
How many innocent South Vietnamese citizens were killed during the Vietnam war? 
Chemistry(Please help)
Calculate the concentration of HC6H6O6 in an aqueous solution of 0.0851 M ascorbic acid, H2C6H6O6 (aq). I do not know how to start this 
physics
Calculate the power of a device that requires 1.98 mA at 25.5 V. I know how to do the problem. i am just confused on how to convert megaAmps(which is mA right?) to amps. i think there are 1million amps in one mega amp? is that correct or is it the other way. so would you do 1.... 
Chemistry
What is the percent by weight of a solution prepared by dissolving 25 g of NaCl in 150 g of water? What is the volume of water in a 1 L bottle of 37% rubbing alcohol by volume? 
Chemistry
A buffer solution is prepared by adding 14.37g of NaC2H3O2 and 16.00g of acetic acid to enough water to make 500mL of solution. What is the initial concentration of C2H3O2 in the solution? Ka(HC2H3O2)=1.8e5 HC2H3O2 = H3O+ + c2h3O2 the molar mass of NaC2H3O3 = 82.04 I know ... 
Chemistry(Please help)
so for kb I do 1e14/.15? 
Chemistry(Please help)
Calculate the pH of an aqueous solution of 0.15 M potassium carbonate. I know that pH = log(H30+) but I am not sure how to start this problem. 
biology
is insomnia the same thing as sleep deprivation. im pretty sure they are different but i just wanted to check. also what in the brain causes insomnia. What parts of the brain create it and what are the functions? 
math
How many 2 quart pitchers could you fill with 512 fluid ounces of juice????? 
Chemistry
If you add 0.35grams NaF to 150mL of a 0.30M HF, what is the pH of the resulting solution? To start off would I use the value of 1.4e11 for F^^ and 7.2e4 for HF? Chemistry(Please help)  DrBob222, Tuesday, April 10, 2012 at 12:04am This is a buffer problem. pH = pKa + log(... 
Chemistry(Please check)
So it would be 27x^4, so I divide 5.0e33 by 27 to get 1.8e34 and then raise this to the 1/4 power which I got 4e9. 
Chemistry(Please check)
What is molar solubility of Al(OH)3 at 25 degrees C given the solubility product Ksp = 5.0e33? I set this up as Al^3+ + 3OH^ Ksp=[Al^3+][OH^]^3 5.0e33 = (x)(3x)^3 Before I go any further did I do this correctly? 
Chemistry
You have 250mL of a 0.56M solution of sodium acetate. How many mL of 0.50M acetic acid should be added to make a buffer of pH 4.40? I think this is a buffer system so I would use pH=pka + log base/acid so would I set this up as 4.40 = 4.74 + log base/ 1.8e5 from acetic acid? 
Chemistry(Please help)
So it would be pH=4.74 + log base/acid and I use 7.2e4 for HF but after I convert g NaF in 150mL to M is this what I use for the base? 
Chemistry(Please help)
If you add 0.35grams NaF to 150mL of a 0.30M HF, what is the pH of the resulting solution? To start off would I use the value of 1.4e11 for F^^ and 7.2e4 for HF? 
Chemistry(Please check)
. Ksp for Fe(IO3)3 is 1014. Two solutions, one being iron(III) nitrate and the other being sodium iodate, were mixed. At the instant of mixing, [Fe3+] = 104M and [IO3] = 105M. What happens? My answer is that a precipitate forms because Qsp > Ksp. Would you agree? ... 
Math
For an experiment on the titration of a supernatant liquid I need to calculate the number of moles of S2O3^2^ ion required using the volume of SrIO3 solution(supernatant liquid) from the two trials that were conducted. For both trials the volume of SrIO3 was 9.5mL. So first I... 
Chemistry
A saturated solution of a certain metal(II) chloride has a chloride ion concentration of 0.032M. The Ksp for this compound can be determined to be is? This is similar to another question I posted that gave the Ksp and I had to find the pH. I am not sure how to start this ... 
Chemistry(Please help)
For the second way, where did the 2.29e5 come from? 
Chemistry(Please help)
For an acetic acidsodium acetate buffer to have a pH of 4.64, what molar ratio of CH3COOH to Na+ CH3COO– is needed? I know that the Ka value for acetic acid is 1.8e5 and that I have to divide this value by the value of sodium acetate but I do not understand how you get ... 
Chemistry(Please check answers)
1)What is the pH of a saturated solution of lead(II) hydroxide? The Ksp= 4.0e15 Pb(OH)2 4.0e15 = (x)(2x)^2 = 4x^3 I divided by 4 and took the cube root and got 1.12e5 but I am not sure I took the cube root correctly. log(1.12e5)= 4.95 144.95 = 9.05 The answer choices ... 
Chemistry(Please check)
. Ksp for Fe(IO3)3 is 1014. Two solutions, one being iron(III) nitrate and the other being sodium iodate, were mixed. At the instant of mixing, [Fe3+] = 104M and [IO3] = 105M. What happens? My answer is that a precipitate forms because Qsp > Ksp. Would you agree? 
Chemistry(Please check)
. The insoluble salts AV, B2W, C2X3, DY2, and EZ3, which were formed from the metal ions A+, B+, C3+, D2+, and E3+ and the nonmetal ions V1– , W2–, X2–, Y1–, and Z1–, all have the same Ksp value. The salt with the highest molar solubility is AV B2W ... 
Chemistry(Please check)
Which of the following mixtures will be a buffer when dissolved in 1 liter of water? 0.10 mol Ba(OH)2 and 0.20 mol HCl 0.30 mol KCl and 0.30 mol HCl 0.40 mol NH3 and 0.40 mol HCl 0.20 mol HNO2 and 0.10 mol NaOH 0.20 mol HBr and 0.10 mol KOH My answer is that HNO2 and NaOH will... 
Chemistry(Please check answer)
The solubility product expression for mercury(I) iodide, Hg2I2 is Ksp = ? My answer is [Hg2^2+^][2I^^]^2^ Would you agree? 
Chemistry(Please help)
What is the pH of a 5.06E2 M aqueous solution of sodium acetate? I know that I would set this up the same way I did for the previous question that I posted. I am just confused on how to find the Ka. I know it is kw/kb but for what compound is what I do not know. Chemistry(... 
Chemistry(Please help)
The solubility product expression for mercury(I) iodide, Hg2I2 is Ksp = ? My answer is [Hg2^2+^][2I^^]^2^ Would you agree? 
Chemistry(Please check answer)
most to least soluble. AgCl is more soluble than Ag2CO3 which is more soluble than Ag3PO4. 
Chemistry(Please check answer)
The Ksp values for three salts are given: AgCl = 1.0e10 Ag2CO3 = 6.3e10 Ag3PO4 = 2.0e21 Determine the order of solubility for these three salts. My answer is AgCl > Ag2CO3 > Ag3PO4. Would you agree? Thank you. 
Chemistry(Please help)
I set this up as 5.55e10 = x^2/0.0506x After converting to pH I got 5.27 but it said that this was incorrect so maybe I do need to use a quadratic, but I am not sure how to go about this. 
Chemistry(Please help)
So for Kb I did kw/ka = 1.0e14/1.8e5 = 5.55e10 . Now I would multiply this by 5.06e6 and take the square root and then covert to pH by taking the log. Is this correct? 
Chemistry(Please help)
so for Kb 
Chemistry(Please help)
ok thank you!