Wednesday

April 1, 2015

April 1, 2015

Total # Posts: 468

**chem**

how many grams of sulfur are needed to react w/ 246 grams of mercury to form HgS? Hg + S ==> HgS unless your instructor insists on writing S as S8, in which case it will be 8Hg + S8 ==> 8HgS. The answer will be the same no matter which way the equation is written. I ...
*July 16, 2007*

**Geography**

1) What is the relationship between an ecozones GDP and area? 2) What is the relationship between an ecozones GDP AND population? ..please help. I thank you in advance. These sites have information that should help you. http://canadianbiodiversity.mcgill.ca/english/ecozones/...
*May 23, 2007*

**pH**

im trying to calculate the pH of a 1.0L soln containing 53.8 g of completely dissociated Mg(CN)2. is this the diss. equation? Mg(CN)2 + water --> MgOH + 2CN^- i dont think i did the problem rite b/c i got 15.7 for the pH. i got 53.8M Mg(CN)2 for the initial conc. or i think...
*May 18, 2007*

**balanced equation**

? MnO4– + ?H+ + ?C2O42– --> ?Mn2+ + ?H2O + ?CO2 what's the balanced equation? correct coefficients? is it 1MnO4- + 2H+ + 1C2O42- --> 1Mn2+ + 1H20 + 2CO2 ? c2042..? are you missing parenthesis somewhere? oh i see, no i believe this is correct: MnO4- + 8h+ + ...
*April 29, 2007*

**chemistry**

Write a net ionic equation for the reaction of the aqueous species ammonia and hydrofluoric acid. I don't think mine is coming out right- I don't know how NH3 reacts with other species, because I end up getting hydrogen as both an anion and a cation in the same species...
*April 29, 2007*

**chemistry**

How many electrons are transferred in the reaction of hydrogen peroxide with iron (II) ion in acidic solution to form iron (III) ion and water? i'm not sure if iposted this already... sorry if i did :) Fe^+2 ==> Fe^+3 + e 2e + 2H^+ + H2O2 ==> 2H2O Multiply equation 1...
*April 22, 2007*

**oxidation**

In the reaction of hydrogen peroxide with iron (II) ion in acidic solution to form iron (III) ion and water, the oxidizing agent is... ? Fe(II) ==> Fe(III) H2O2 ==> H2O. Fe goes from +2 to +3, that is a loss of electrons, so it is oxidized (by definition, oxidation is ...
*April 19, 2007*

**pH- from saturday**

i posted this question previously and got help however im still having some confusion. can u clarify ? what's the pH of the acid HC2H3O2 with concentration of .15? Bob Pursley worked that problem for you and gave it as [x^2/0.15] = Ka. What is it you don't understand? ...
*April 15, 2007*

**pH- really hard one**

What is the pH of the solution created by combining 1.00 mL of the 0.10 M NaOH(aq) with 8.00 mL of the 0.10 M HCl(aq)? with 8.00 mL of the 0.10 M HC2H3O2(aq)? NaOH + HCl ==> NaCl + H2O So all the NaOH is neutralized leaving NaCl, which will not affect the pH either way, ...
*April 15, 2007*

**pH- part 2**

how much .10M Base (in mL) is needed to neutralize 8.00mL of .10M Acid? base- NaOH, acid- HCl, base volume (mL)- ? base- NaOH, acid- HC2H3O2, base volume (mL)- ? VaNa=VbNb Vb= 8ml*.10N/.10N= 8m.
*April 14, 2007*

**pH**

what's the pH of the acid HCl with concentration of .15? the acid HC2H3O2 with concentration of .15? I figured out the pH of HCl, but I'm still not sure how to find the other one... What is the dissociation constant for acetic acid? K= [H+][ace-]/.15 pH= -log sqrt (.15...
*April 14, 2007*

**equilibrium constant**

find eq constant at 910K. CCl4 (g)--> <--CCl4(l) given: Gf CCl4(g)= -53.7 Gf CCl4(l)= -68.6 G Products - G reactants = Delta G. Delta G = -RT ln Keq
*April 12, 2007*

**English/Grammar/Appositives**

Are the commas a correctly placed? 1. The term hardware refers to the computing equipment, itself. 2. The year, 1975, marked the arrival of the microcomputer Neither of those sentences needs any commas. =) Can u give me 3 examples of similies, metaphors and personification in ...
*April 10, 2007*

**equilibrium III**

what's Kp if Cl2CO was found to be 7.46% decomposed at 395'C when initial pressure is 7.60atm. Cl2CO --> <-- CO + Cl2 Initial p = 7.60 atm. 7.46% decomposed. (CO) = 7.60*0.0746 = ?? (Cl2) = same ((Cl2CO) = 7.60*(0.9254) = ?? Kp = pCO*pCl2/pCl2CO Post your work if...
*April 10, 2007*

**equilbrium II**

when CO2 (.15mol) and H2 (.302g) in a 500L vessel at 576'C are allowed to come to equilibrium the mixture contains .000183 mol/L of H20. what is the equilibrium concentration of CO? CO2 + H2 --> <-- CO +H2O The equilibrium concentration of H2O = the equilibrium ...
*April 10, 2007*

**equilibrium**

when Br2 (5.7mol) and Cl2 (.0934mol/L)in a 61 L vessel at 604'C are allowed to come to equlibrium the mixture contains .0523 mol/L of BrCl. What concentration of Cl2 is reacted? - i know how to find the Kc... Br2 + Cl2 ==> 2BrCl 0.0523 mol/L BrCl at equilibrium in a 61 ...
*April 10, 2007*

**molarity**

calculate the molarity of k+ in a soln prepared by adding .2L of .200M K3PO4 and 75.0mL of .5M K3PO4. assume volumes are additive. A few of steps here and more than one way to answer the problem You need to calculate the total number of moles of K3PO4 from the two volumes and ...
*April 5, 2007*

**equilibrium concentration**

A standard solution of FeSCN2+ is prepared by combining 9.00 mL of 0.200 M Fe(NO3)3 w/1.00 mL of 0.0020 M KSCN. The equilibrium concentration of FeSCN2+ ([FeSCN2+]std) for this standard solution is assumed to be ? M. Wouldn't that be 0.002 x 1/11 = ??
*April 4, 2007*

**equilibrium**

The standard solution of FeSCN2+ (prepared by combining 9.00 mL of 0.200 M Fe(NO3)3 w/1.00 mL of 0.0020 M KSCN) has an absorbance of 0.510. If a trial's absorbance is measured to be 0.250 and its initial concentration of SCN– was 0.00050 M, the equilibrium ...
*April 4, 2007*

**chemistry**

A student performed the freezing point depression experiment according to directions but mistakenly recorded the mass of lauric acid as 8.300g instead of8.003g. The calculated molar mass of the unknown acid will be GREATER/LESS than true value b/c mass of lauric acid appears ...
*April 3, 2007*

**chemistry/ molarity, molality**

A solution is made by mixing 20.0 mL of C6H5CH3, d=.867g/mL, with 140.0mL of C6H6, d=.874g/mL. assuming that the volumes add upon mixing, what is the molarity? what is the molality? i know that molarity= moles/L and molality= moles sol/kg solvent... but im not sure which ...
*April 3, 2007*

**Micro Economics**

Briefly explain the following: (a)Economic cost and accounting cost. (b)Free market economy and mixed economy. (c)Marginal utility theory and indifference curves analysis. Please note that we don't do students' homework for them. Once YOU have come up with a response ...
*March 23, 2007*

**Mass Communication**

what is meant by persuasive communication?Explain breifly I've clicked through a few and have only seen what seem to be a lot of homework questions. But I have not understood what your confusion is on many of them. Do you now understand what they are asking? The act of ...
*March 23, 2007*

**Mass Communication**

The act of communication is best understood as one that has social implications.Explain briefly Please note that we don't do students' homework for them. Once YOU have come up with a response to YOUR questions, please re-post and let us know what you think. Then ...
*March 23, 2007*

**Spanish**

I wrote a story for my Spanish class; could someone please proof-read part of it for me? Thanks! Ella se cae, arrodillada sobre la orilla. Es donde ellos tuvieron sus primero encuentra. Llorando, ella se depila los pétalos de una flor. Ella gota los pétalos en el...
*February 27, 2007*

**calc.- trig substitution**

s- integral s 1/ [ (x^4) sq.rt(x^2+9)] i know x=3tanx sq.rt(x^2+9)= 3 secx dx= 3/[cos^2(x)] so far i know: = 1/ (3tan^4(x)) 3secx cos^2(x)) dx =1/ 81 [ (sin^4 (x)/cos^4 (x)) (1/cosx) (cos^2(x))] then i'm not really sure what to do next
*February 26, 2007*

**chemistry**

if a structural isomer has an OH attached, i don't understand why it's unlikely that it'll be a liquid at room temperature. I think, I'm not sure, but because both O and H are gases I can think of many alcohols that are liquid at room temperature.
*February 25, 2007*

**trig integration**

i'm having trouble evaluating the integral at pi/2 and 0. i know: s (at pi/2 and 0) sin^2 (2x)dx= s 1/2[1-cos(2x)]dx= s 1/2(x-sin(4x))dx= (x/2)- 1/8[sin (4x)] i dont understand how you get pi/4 You made a few mistakes, check again. But you don't need to do any ...
*February 18, 2007*

**trig integration**

s- integral endpoints are 0 and pi/2 i need to find the integral of sin^2 (2x) dx. i know that the answer is pi/4, but im not sure how to get to it. i know: s sin^2(2x)dx= 1/2 [1-cos (4x)] dx, but then i'm confused. The indefinite integral of (1/2) [1-cos (4x)] is (x/2...
*February 18, 2007*

**chemistry- absorbance & transmittance**

An unknown was prepared with the concentration of 0.000120 M. A Beer's Law plot was prepared using the absorbance values from standard solutions of ASA and a line drawn through all the points passed through the origin with a slope of 1750.0 M–1. The expected ...
*February 16, 2007*

**molarity**

An aspirin tablet weighing 0.475 g has been analyzed and contains 68.2 % ASA (180.16 g/mol) by mass. A student dissolved the tablet in hot NaOH and the cooled solution was diluted with DI water to the mark in a 250 mL volumetric flask. Exactly 3.00 mL of the solution was ...
*February 16, 2007*

**US History - to Ms. Sue**

First of all, thank you SO much for clarifying my question! It is part of an overall essay topic that I can't figure out how to answer: Compare and contrast the methods used by late nineteenth century corporations to control competition - especially the pool, trust, ...
*February 11, 2007*

**US History**

What was so bad about pools in the late 1800's? I understand what they were but they were banned by the government in the Interstate Commerce Act and I don't understand why they were so harmful? How did they give more money to railroad companies? I'M SO CONFUSED. ...
*February 11, 2007*

**Hess' law**

Which of the following is the best definition of Hess' Law? A. Heat is always released by the decomposition of 1 mole of a compound into its constitute elements. B. Since enthalpy is a state function, it will be different if a reaction takes place in one step or a series ...
*February 9, 2007*

**critical thinking**

what is the rhetorical device for: What is the difference between "sugar free" and "no sugar added"? sugar free means no sugar at all and non sugar added means it has natural sugar nd they don't add any extra bob do you know what the rhetorical device ...
*February 8, 2007*

**Chemistry - Rate Determining Step**

The rate law for the reaction 2NO (g) + Cl2 (g) -> 2NOCl (g) is given by rate = k[NO][Cl2] A mechanism involving the following steps has been proposed for the reaction: NO (g) + Cl2 (g) -> NOCl2 (g) NOCl2 (g) + NO (g) -> 2NOCl (g) If this mechanism is correct, what ...
*February 6, 2007*

**math**

You inherit $18750 but the conditions are that for teh first year, the money must be invested in two stocks paying 10% and 11% interest, respectively. How much should be inbested at each rate if teh total interest to be earned for teh year at $1962.51? Be sure to specify what ...
*February 6, 2007*

**Economics**

In order to answer the question, the theory of consumer behavior must be examined. Utility is the satisfaction or pleasure a consumer gets from the consumption of a good or service (all-you-can-eat buffet) and total utility is the total amount of satisfaction derived from the ...
*February 4, 2007*

**h bonding**

which exhibits hydrogen bonding (there can be more than 1) 1. IF7 2. SiH4 3. CH3CH2OH 4. (CH3)2CHOH 5. PCl3 6. CH3CHCHCH3 * do you have any tips for figuring it out? H bonding, by definition, takes place with H of one molecule and a highly electronegative atom (usually O, N, F...
*February 1, 2007*

**social studies- articles of confederation**

what can the congress do http://www.google.com/search?q=articles+confederation+congress&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7 Lots of information here. =)
*January 30, 2007*

**spelling**

grass to lawn toss to throw
*January 16, 2007*

**spelling**

the answer to accept except threw is through
*January 16, 2007*

**tofu**

does tofu have any naturally occuring bacteria in it? When I incubated the tofu juice, a white bacteria grew, but I can't find any information stating what it might be. It should not have an "natural" bacteria in it. Bacteria are not used in the production ...
*December 1, 2006*

**chemistry**

What is the role of energy in physical changes? Please and thank you!!!
*November 7, 2006*

**chem**

I have a few questions. 1. write the net ionic equation for a precipitate when solutions of magnesium nitrate and potassium hydroxide form. When I did this equation out, both products were soluble. Am I doing this wrong? 2. A 50.00 mL sample of .0250 M silver nitrate is mixed ...
*October 19, 2006*

**Physics**

A rocketship, travelling away from earth with a speed of 0.8c, sends regular radio signals which are recieved on Earth every 45.2 min. According to the rocketship astronauts, how frequently are the signals being sent? I really need help. Its a basic question yet har for me. ...
*October 7, 2006*

**Economics**

Four roommates are planning to spend the weekend in their dorm room watching old movies, and they are debating how many to watch. Here is their willingness to pay for each film: Orson Alfred Woody Ingmar Frist film 7 5 3 2 Second film 6 4 2 1 Third film 5 3 1 0 Fourth film 4 2...
*September 30, 2006*

**math**

the number of sides in an argument There probably would be at least one side of an argument for each person participating. It would also depend on the number of available options to the situation being discussed. I hope this helps a little. Thanks for asking.
*September 23, 2006*

**math**

Hi, I have a math question that I need help with: g:-> 3(1.3)^x State equations for any asymptotes to the graph of g. I know what an asymptote is, but I do not understand this question...so lost. Help would be greatly appreciated. Thanks so much I'm a little unsure what...
*September 16, 2006*

**algebra**

give the demensions of rectangles with the perimeters of 70 feet and length-to-width ratios of 3 to 4, 4 to 5, and 1 to 1. Ok, the perimeter is 70 and perimeter = 2(length + width) The ratio is length:with=3:4 so length = (3/4)width 70 = 2(length + width) =2((3/4)width + ...
*September 12, 2006*

**algebra**

What is the width of a rectangle with a perimeter of 70 feet if its length is 1 foot? 2 feet? L.feet? perimeter = 2(length + width) If perimeter = 70 then 35= length + width Now substitute 1,2,and L and solve for width. how do you find the L. feet? L is supposed to be any ...
*September 12, 2006*

**algebra**

suppose the length of a rectangle increases,but the perimeter remains at 70 feet. How does the width change? Either the width increases, decreases or remains the same. Which of these three choices makes the most intuitive sense? We know perimeter = 2(length +width) If ...
*September 12, 2006*

**math riddle**

Estimate a population: To study a species of fox, a team captures and tags 25 foxes from a large forest and then releases them. The following week they capture 15 foxes and find 5 are tagged. Estimate the number of foxes in the forest. This is a proportion problem. We know ...
*September 8, 2006*

**Stat/trig question, please help me, thanks**

In 1995, more than 1.1 million students in the U.S. took the SAT. On the mathematics section, the mean =507, s=112 (standard deviation). Students recieve scores rounded to the nearest 10. What is the interval of student scores that lie within one standard deviation of the mean...
*September 5, 2006*

**math problem**

the circle graph at the right shows eye colors of the students in Mr.Chare's 4th hour class. If 7 students have either green or hazel eyes, how many students are there in the class? Circle graph is.. 12% gray 24%hazel 4% green 36% brown 24% blue I need help solving this, ...
*August 30, 2006*

**Bio Bio**

You have just located a nucleolus in the nucleus. You are able to excise this area of the genome and express the genes of this chromosomal fraction in vitro (in a test tube). What genes would you most likely find expressed from this portion of the cell's DNA? I. tRNA II. ...
*July 22, 2006*

**Bio Bio Please check answer**

Because codons are triplicates, there are ______ possible nucleotides combinations that could make a codon; each giving rise to one specific amino acid. Yet, there are only 20 amino acids used to produce proteins. Thsus, the gentic code is said to be _______. I. 16, unambigous...
*July 22, 2006*

**Bio Bio**

Please help me out with this: You have just located a nucleolus in the nucleus. You are able to excise thsi area of the genome and express the genesof this chromosomal fraction in vitro (in a test tube). What genes would you most likely find expressed from this portion of the ...
*July 22, 2006*

**"write a paragraph on book's thesis"?**

I'm going into AP (advanced placement) European History, grade 10, and our summer reading assignment was to read a <i>A World Lit Only By Fire</i>, a book about the tenaissance. Along with this assignment, I'm required to write a paragraph about the book&#...
*August 31, 2005*

**grammar**

please correct this sentence: A)HOPEFULLY, we B)WILL BE able to complete the building C)BEFORE the rainy seas sets D)IN. E)NO ERROR i already know the answer is A, but i'm not sure why. can u please explain, thanks. I believe the writer means when the "rainy season ...
*July 19, 2005*

**grammar**

please correct this sentence: the reason i A) WILL not be going to mexico is C)BECAUSE i will use up all my money D)IN ATTENDING an important meeting in singapore. E)NO ERROR i already know that the answer is c, but please explain. thank you.
*July 19, 2005*

**math**

If a and b are positive integers and their product is 3 times their sum, what is the value of 1/a + 1/b? Given that ab = 3(a + b). From this, ab/3 = a + b. Dividing through by ab yields 1/a + 1/b = 1/3.
*June 30, 2005*

**math**

there are 12 men on a basketball team, and in a game 5 of them play at any one time. if the game is 1 hr long and if each man plays exactly the same amount of time how many minutes does each man play? a) 10 b) 12 c) 24 d) 25 e) 30 b) 12 NO. Its d) 25. With a 60 minute game and...
*June 29, 2005*

**math**

if A (2, -1) and B (4,7) are endpoints of a diameter of a circle, what is the area of the circle? a)16pi b) 17pi c) 18pi d)144pi e)1156pi Plot the two points and join 'em with a line. Now plot another point C (4, -1). And then simply run a line from B down to the new point...
*June 24, 2005*

**math**

two cylindrical tanks have the same height, but the radius of one tank equals the diameter of the other. if the volume of the larger is k% more than the volume of the smaller, k= ? a)50 b)100 c)200 d)300 e)400 small tank volume: pi*(r/2)^2*h big tank volume: pi*r^2*h factor ...
*June 23, 2005*

**math**

if anthony had 3 times as many marbles as he actually has, he would have 1/3 as many marbles as Billy has. what is the ratio of the number of marbles Anthony has to the number of marbles Billy has? a)1:9 b)1:3 c)1:1 d)3:1 e) 9:1 1:9 Ex: Anthony has 3 marbles and Billy has 27. ...
*June 23, 2005*

**math**

a rectangle has a perimeter equal to circumference of a circle of radius 3. if the width of the rectangle is 3, what is the length? a) 3pi-3 b) 4.5pi-3 c)6pi-3 d)9pi-3 e)cannot be determined 3*2*pi=3+3+2x where x=side of rectangle 6pi-6=2x 3pi-3=x
*June 23, 2005*

**Chemistry Suspension Examples...**

orange juice is a good example!! Because the state of a subthat is mixed but never really be dissovled. We learend about this in science class.
*June 15, 2005*

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