chemistry! URGENT

61,713 results, page 25
  1. Chemistry

    I have a gr 10 chemistry unit test coming up can someone please refresh my mind on this unit? and tell me what things i should practice for the test? Tyy
  2. Chemistry

    chemistry question. How many grams of silver sulfide can be produced by heating 45 grams of silver excess sulfer?
  3. chemistry

    what is an indicator for chemistry? How is this for a definition? Thanks A susbtance that changes colour when added to a base or an acid. The colour it changes to will depend on which it is added to.
  4. chemistry

    The decomposition of an aldehyde solution in carbon tetrachloride is a first order reaction with a rate constant of 1.20 x 10-3 min-l. If we start with [aldehyde] = 0.0500 molar, what will the concentration be 150 minutes later? a. 0.00900 M b. 0.0418 M c.
  5. chemistry

    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) A. 20.2 B. 2.06 X 10-4 C. 4.49 D. 4.84 X 10-3 E. 0.223 eliminated
  6. chemistry

    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) A. 20.2 B. 2.06 X 10-4 C. 4.49 D. 4.84 X 10-3 E. 0.223 eliminated
  7. Maths

    In a class of 80 students,53 study Art,60 study biology,36 study Art and biology,34 study Art and chemistry,6 study biology but not chemistry.Illustrate the information on a Venn diagram.Determine the number of students who study Art only And Chemistry
  8. Microconomics [URGENT]

    In the short run, do perfectly competitive firms have a loss of profit or a break even when MC = AVC? Do these firms choose whether to produce or shutdown or both? Do they choose to produce nothing or a specific quantity or both? If MC = ATC in the short
  9. CHEM URGENT PLZ

    1.Which of these substances has bent molecular geometry around the oxygen atom? Multiple correct answer may apply. a.water b.isopropyl alcohol (rubbing alcohol)** c.acetone** d.diethyl ether. 2.Which of these species are polar? Ignore slightly polar C-H
  10. Calculus Help Please!!! URGENT!!!!

    Carbon-14 has a half-life of 5700 years. In a living organism, the ratio of radioactive carbon-14 to ordinary carbon remains fairly constant during the lifetime of the organism. After the organism’s death no new carbon is integrated into the organism’s
  11. chemistry

    For the reaction, A = B + C, the rate law is kA]. If it takes 80.0 seconds for 70.0% of a 10.0 gram sample of A to be transformed into products, what is the value of the rate constant? a. 0.00450 s-1 b. 0.0290 s 1 c. 0.00530 s-1 d. 0.0150 s-1 e. 5.40 s-1
  12. Maths

    In a survey of 200 students of a school, it was found that 60% study mathematics, 45% study physics, 35% study chemistry, 20% study mathematics and physics, 15% study physics and chemistry, 25% study chemistry and mathematics and 10% none of these
  13. Physics Urgent!!!!!

    Newton’s Law of Gravity specifies the magnitude of the interaction force between two point masses, m1 and m2, separated by the distance r as F(r) = Gm1m2/r^2. The gravitational constant G can be determined by directly measuring the interaction force in
  14. Physics Urgent!!

    Newton’s Law of Gravity specifies the magnitude of the interaction force between two point masses, m1 and m2, separated by the distance r as F(r) = Gm1m2/r^2. The gravitational constant G can be determined by directly measuring the interaction force in
  15. Chemistry

    Find the value of delta H net for the following equation: SnBr2(s) + TiCl4(l) -> TiBr2(s) + SnCl4(l) I know that I already posted this once but I am still lost on what to do. I know that TiCl4=-804.2 and SnCl4=-511.3 but I thought that the values for
  16. Chemistry

    For Chemistry, I have to design a coin. What are some anti-counterfeiting measures I could use to prevent people from replicating it? I've googled this, but I haven't found many good ideas. I can only think of putting grooves on the edge of the coin and,
  17. CHEMISTRY

    When doing an ICE Chart in Chemistry, when do you know whether the C is a negative or positive? I was told if the problem gives us reactant concentrations and no product concentration then the reaction goes forward and make the reactant lose and the
  18. College chemistry

    This is my first time taking chemistry and I am VERY VERY confused On the step involved to find out how many calories to warm 58mL of water from 10 degress C to 100 degress C and vaporize it at 100 degress C.
  19. Chemistry

    I was doing a lab today in chemistry, and I do not know if I got my measurements correctly. My teacher gave us a strip (probably 5inches) of Mg. We measured it, and then after that, we had to burn it, and measure the mass of it after it was burn. Would the
  20. english

    hi can someone pleases help me analyze this poem. I need a lot of help In The Gallery Here neither nymph nor naiad ever bathed nor Saint refreshed herself in pristine water, here, in The Gallery, between Tie Rack, Camera Shop, B. Dalton, Radio Shack, Dad's
  21. english

    hi what does the alliteration in the first line of this poem represent In The Gallery Here neither nymph nor naiad ever bathed nor Saint refreshed herself in pristine water, here, in The Gallery, between Tie Rack, Camera Shop, B. Dalton, Radio Shack, Dad's
  22. Math

    Out of 300 student in final year in senior secondary school, 200 are offering biology and the150 offering chemistry how many are offering neither biology nor chemistry
  23. Chemistry

    Analytical Chemistry question: Find the pH and the concentration of each species of lysine in a solution of 0.0010 M lysine*HCL. I know that the pKAs of lysine are (1.77)(CO2H) 9.07 (-NH3) 10.82 ( -NH3) but I am not sure where to go from there.
  24. Chemistry

    Calculate the standard enthalpy change for the reaction 2A+B⇌2C+2D Use the following data: Substance ΔH∘f (kJ/mol) A -247 B -375 C 191 D -483 Express your answer to three significant figures and include the appropriate units. My answer was 285 kJ/mol
  25. Chemistry HELP!!

    A sample of nicotine weighing 0.3204 g was vaporized in a flask with a volume of 487 mL. This sample exrted pressure of 74.3 mm Hg at 20 degrees C. What is the molar mass of nicotine? I know this has to do with N=P*V/R*T. and 1 atm=760 mm Hg. Please help
  26. chemistry

    I did a chemistry lab on polarimetry where we separated two enantiomers into individual salts and then used a polarimeter to determine the specific rotation and optical purity. What is the relationship of the proline salts to one another? i said that being
  27. Chemistry

    A sample of nicotine weighing 0.3204 g was vaporized in a flask with a volume of 487 mL. This sample exrted pressure of 74.3 mm Hg at 20 degrees C. What is the molar mass of nicotine? I know this has to do with N=P*V/R*T. and 1 atm=760 mm Hg. Please help
  28. Chemistry

    Balance the equation: NO2- (aq) + Al (s) --> NH3 (g) + AlO2- (aq) (basic solution) ** please note the "2-" on the NO2- and AlO2- are not subscripts, they are the charges. I missed a few classes in Chemistry and find myself lost. I have tried to learn
  29. Chemistry

    1. Imagine that you work at a company that prepares chemical solutions. You are asked to label a solution to sell to different customers. One customer is a hospital, another is a chemistry lab at a university, and a third is a physics lab at a university.
  30. Chemistry: Electron Configurations

    Write the electron configuration for the following ion. V3+ I got 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2. In simplified form, I got [Ar]4s^2. I checked my answer against the answer given in the back of my chemistry textbook, and the two didn't correspond. The
  31. chemistry help

    our teacher said on our final chemistry lab test there will be a question asking us to convert nanometers to wave numbers, anyone know what the question might be phrased like? also, im not sure i know how to convert, anyone have an example question with
  32. Chemistry

    Convert a pressure of 23.8 in. Hg into kilopascal. Ok so I looked up kilopascal and it Said 1 Kpa = 1000 pa So I began to set it up like this 23.8 / 29.2 x1000 am I correct Chemistry - DrBob222, Thursday, October 13, 2011 at 1:48pm I don't think that will
  33. Chemistry

    Is there a chemistry teacher for jiskha? Or someone that knows what my teacher is talking about? :’( He wants me to: Calculate the number of moles of CO2 in 63.0g of CO2
  34. 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 1.4e-11 for F^-^ and 7.2e-4 for HF? Chemistry(Please help) - DrBob222, Tuesday, April 10, 2012 at 12:04am This is a buffer
  35. Chemistry

    Sorry, just asking a question on chemistry.
  36. Chemistry

    why is chemistry needed
  37. chemistry

    What does a slash (/) mean in chemistry?
  38. chemistry

    Does Chemistry have anything to do with meteorology?
  39. chemistry

    i need help with chemistry homework
  40. Chemistry

    What is another name for mole in Chemistry
  41. chemistry

    why is chemistry so important
  42. Chemistry

    Explain in terms of forces between structural units why H2O2 has a higher melting point than C3H8. Also, which between the two examples has a lower boiling point? NH3 or AsH3 C3H7OH or C2H5OCH3 Can you possibly give me a good website that simply explains
  43. Chemistry

    You wash dishes for a chemistry laboratory to make extra money for laundry. You earn 6 dollars/hr , and each shift lasts 75minutes . Your laundry requires 6quarters/load. How many shifts must you work if you wish to wash 10 loads of laundry?
  44. Chemistry

    A 19th-century chemist, Marcellin Berthelot, suggested that all chemical processes that proceed spontaneously are exothermic. True or False? I thought it was true, but then in my chemistry textbook, I could not find this person's name. Can someone verify
  45. Overdue Science Lesson, Very Urgent.

    1: How does sea-floor spreading occur? A, New materials are being added to the asthenosphere. B, Earthquakes break apart the ocean floor. C, Sediments accumulate at the area of spreading. D, Molten material beneath Earth's crust rises to the surface. 2,
  46. College Chemistry

    Calculate the electrode potential of a copper half-call containing 0.05M Cu(NO3). E^0 Cu2+/Cu = 0.337 V College Chemistry - DrBob222, Tuesday, April 20, 2010 at 5:19pm E = Eo - (0.0592/n)log[(Cu)/(Cu^+2)] Substitute 2 for n and 0.05 M for Cu^+2 and 0.337
  47. chemistry

    Hi, Does anybody know any good websites that can teach me step-by-step basic chemistry (through power points) to AP chemistry? I would greatly appreciate it! Since this is not my area of expertise, I searched Google under the key words "AP chemistry
  48. chemistry

    Would a damp filter paper affect the theoritical yield, calculated actual yield and calculated percent yield. Please help. Chemistry is hard.
  49. Chemistry

    Why use Methyl tert-butyl ether in the organic chemistry lab when separating compounds? separating WHAT compounds and how? as a solvent? It has a low boiling point and isn't very reactive, generally, but there may be other specific reasons depending upon
  50. Chemistry

    according to the bohr model of the hydrogen atom, what is the closest an electron can get to the nucleus? What is the farthest it can get from the nucleus? ( if the latter answer seems absurb, it might amuse you to know that it is the same value predicted
  51. social studies 20-1 (URGENT)

    examine each source below and write in paragraph form, a response in which you: -interpret each source to identify and explain the perspective(s) related to Nationalism. -identify and discuss one or more ideological concepts that are refleted in the
  52. chemistry

    Carbon and silicon are both in Group 14 of the periodic table. (i) Identify compounds which illustrate similarities in the chemistry of carbon and silicon. (ii)Identify compounds which illustrate significant differences in the chemistry of carbon and
  53. Chemistry

    I have 25 million gallons of water at a pH of 6.5. I add 17.4 million gallons of 12.5% by wt sodium hypochlorite (NaClO) at a pH of 12.5 to this water. What will my pH of my final solution be? It's been about 5 years since I took chemistry and I just don't
  54. chemistry

    which of the following is true regarding the inner transition elements? A. their valence electrons can be located in both s and f sublevels B. They occupy the d block of the periodic table C. These include the lanthanides and actinides and do not have f
  55. Chemistry

    Aspirin can be prepared in the chemistry laboratory by the reaction of salicylic acid with acetic anhydride. What volume of acetic anhydride is required to produce one killogram of aspirin assuming 100%yield
  56. Chemistry/ Physical Chemistry

    Napthalene is dissolved in a liquid with which it forms an ideal solution at 25C. The normal boiling point of napthalene is 80.2 C and ^fusH for napthalene is 19.0 KJ/mol. Determine the solublity of napthalene in this liquid at 25 C.
  57. chemistry

    I have a question in chemistry relating to identifying a compound that would precipitate the iron ions out of a water supply. I am unsure of a compound that would react to produce the iron as a precipitate that could be removed. Thoughts?
  58. Chemistry

    Does anyone know of any sites that make learning to balance equations easy? I just transferred to a new school and the chemistry class is way ahead of my old class. I really don't get it. Please help since there is a test tomorrow and it's on stuff that
  59. Chemistry

    For a chemistry lab, I have to calculate the heat of combustion of paraffin wax. So how would I do that? And for the second part of the lab, I have to calculate the heat of fusion of ice from my data. How would I do that? I'm kind of confused so can I get
  60. chemistry

    can you please give me one practical application of analytical chemistry in being a medical technologist? i know it will determine the separation event happening on the lab test... but is that already a practical application? or i have to cite a deeper
  61. chemistry

    i have to do a "chemistry of cooking" project for my chem class. for the project i need to convert pounds, grams, and ounces into moles, but i do not know how. for example, i need to convert 453.5g of beef into mols. how do i do that? do i need to know the
  62. math-urgent please help

    Newton’s Law of Cooling states that the temperature of a heated object decreases exponentially over time toward the temperature of the surrounding medium. The temperature u of a heated object at a given time t can be modeled by the following function:
  63. chemistry

    So I have to make a green cleaner for a project in chemistry. I think my ingredients should be: vinegar, salt, water, and lemon juice. But I don't know how I would write that exactly as a chemical formula. How could I write a chemical equation if I have 4
  64. Chemistry

    The energies, E, for the first few states of an unknown element are shown here in arbitrary units. n 1 E -11 n 2 E -5 n 3 E -2 n 4 E -1 n ... E ... n infinite E 0 A gaseous sample of this element is bombarded by photons of various energies (in these same
  65. MATH

    Please help me with these problems. Work and answer is appreciated! :) thanks. 1. Find on the interval theta is greater than or equal to 0 and less than 2pi; then find the general solution: 5tantheta+1=-2.89 16cos^2theta-6=3 6sin^2theta+sintheta=2
  66. Chemistry

    Chemistry question: Given: CH4 + 2O2 ~ CO2 + 2H2O C - H = 99 kcal O - O = 119 kcal C = O = 192 kcal O - H = 111 kcal Calculate the change in energy for the CH4 - O2 system.
  67. 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,
  68. Biology---Urgent

    14. Surface area is an important factor in limiting growth cell because a. the cell may become too large to remove enough wastes. b. materials can't enter the cell if it's too large c. the cell can burst if the membrane becomes too large d. waste products
  69. Organic chemistry

    please help me with these what are the functional group(s) in Lexiva (Fosamprenavir Calcium)? i only know that it has an amine group but i'm not sure if there is another group!!! and how can i relate Lexiva to chemistry?(ideas please)
  70. Further maths

    In an examination 31 candidate passed Chemistry,29 passed Physics 3 failed both subjects.lf 50 candidates sat for the examination how many of them passed Chemistry only.
  71. Spansh #2 (URGENT)

    Can someone please check my work? Julieta's friends all have different personal tratis. Complete the sentences below using the verb in parenthesis. 1. Maria <es> intelegente. (ser) 2. Julio y Marcos <están> en Ecuador. (estar) 3. Norma y yo
  72. Chemistry - HELP IGCSE

    I have a chemistry exam tomorrow and I don't get the double bonding in covalent bonding I tried many websites , textbooks and other books and yet nothing worked Can someone please explain it clearely and in a simple way and please don't put any links for
  73. chemistry

    Effusion/Diffusion Chemistry Help!!! If 4.83mL of an unknown gas effuses through a hole in a plate in the same time it takes 9.23mL of Argon, Ar, to effuse through the same hole under the same conditions, what is the molecular mass of the unknown gas?
  74. chemistry

    Where can I find the answers to these questions in my text, "fundamentals of analytical chemistry" by skoog, west, holler and crouch. 1. Why is acetylsalicylic acid analyzed using back titration? 2. Discuss the importance of simmering the tablet in the
  75. aed 205

    Read the following vignette and identify the factors that threaten the activity flow of the lesson. Once you have identified the problems, explain how you would avoid the problems if you were the teacher. Here is the story Mrs. P.waits while her
  76. Chemistry 2

    36.) Suppose a chemistry student discoveres that a block of pure ice is left on her porch as she goes to school one day. What will be the percent composition of the pure ice block?
  77. physics(URGENT!!!!!)

    A ruler stands vertically against a wall. It is given a tiny impulse at θ=0∘ such that it starts falling down under the influence of gravity. You can consider that the initial angular velocity is very small so that ω(θ=0∘)=0. The
  78. physics(URGENT!!!!!)

    A ruler stands vertically against a wall. It is given a tiny impulse at θ=0∘ such that it starts falling down under the influence of gravity. You can consider that the initial angular velocity is very small so that ω(θ=0∘)=0. The
  79. Chemistry

    Hello, we recently did a lab in our chemistry class to analyze an Unknown amount Calcium Carbonate which was titrated with EDTA. Our titration results were: mass of the unknown CaCO3 was 0.172 g and the mL of EDTA added was 30.7. How do I find the percent
  80. CHEMiSTRY PROJECT

    For chemistry I have to make a comic strip about gold. The comic strip has to included all the important facts i.e. atomic mass, symbol, weight,etc... Any suggestions on what my comic strip could be or any ideas. Thanks ahead for you help.
  81. Physics - urgent

    I already asked this and was given an answer, but I don't fully understand it and so would like a further explanation. What I asked was... An electron is accelerated through a uniform electric field of magnitude 2.5x10^2 N/C with an initial speed of
  82. Chemistry

    Hi there, can someone please help me with this chemistry problem? Write the equation for the acid-base reaction that takes place when nitric acid (HNO3) dissolves in H2O. (Include the phase of each substance.) I got HNO3(aq) + H2O --> H3O+(aq) +
  83. Chemistry

    Hi Dr. Bob, I am quite stumped on how to figure out when chemical equations have a REACTION or NO REACTION. I have read the material in my textbook and even took out a chemistry books for the "Utterly Confused" to try to figure this out. Example: Zn(s) +
  84. science

    i really need to know what alkalis and acids are in soap!!! FOR TOMMOROW! Thank you for using the Jiskha Homework Help Forum. Here is something on soaps from a Chemistry site: http://www.cleaning101.com/cleaning/chemistry/ page 2 =
  85. Chemistry

    I'm doing a lab in chemistry and I need help with a question, here is my data: Mass Before: 26.4 g After burned: 26.25 g Total Mass burned: .15 g 1. Calculate the mass of oxygen that was consumed while the candle burned. I think I need to use mole
  86. chemistry, ap chemistry

    At 800 K the equilibrium constant for I2(g) 2 I(g) is Kc = 3.1 10-5. If an equilibrium mixture in a 10.0-L vessel contains 3.56 10-2 g of I(g), how many grams of I2 are in the mixture?
  87. Chemistry

    I need help with Chemistry homework.. I don't know how to write formulas..Please help me! Write the formulas for silicon dioxide.
  88. Physics URGENT!!!

    A wheel has a radius of 3.5 m. How far (path length) does a point on the circumference travel if the wheel is rotated through an angle of 71.0°? B) A wheel has a radius of 3.5 m. How far (path length) does a point on the circumference travel if the wheel
  89. Advice...about chemistry degree Dr.Bob

    Based on the question topic posted by Britney below titled:In your opinion (your answer to this reminded me of something) (I posted the same thing there but I thought it was improper to piggyback on that post so I posted this under a new topic) I don't
  90. Urgent Science!!!

    1. Which of the following is NOT a fossil? (1 point) outline of a fern found in a rock petrified wood in the desert baby mammoth found in a glacier old stone tools found in a cave 2. _____ is based on the idea that younger rock layers are deposited on top
  91. english

    hi can someone pleases help me analyze this poem. I need a lot of help In The Gallery Here neither nymph nor naiad ever bathed nor Saint refreshed herself in pristine water, here, in The Gallery, between Tie Rack, Camera Shop, B. Dalton, Radio Shack, Dad's
  92. French (URGENT)

    Sra, can you please proofread my paragraph? Bonjour, Ici un petit paragraphe à propos de mon ami James. James est d'Alberta mais il habite Vernon, BC de Canada. Il a quinze ans. Il a un frère cadet nommé Thomas. Thomas a quatorze ans. James aime
  93. Chemistry

    Hi, I have few questions from a chemistry lab that i did, 1) I'm not sure whats the point of heating a nitrate (NaNO3) 2) I'm not sure why you add NaOH to NaNO3 after it has dissolved in water 3) I'm not sure why do we have to test what gas is produced
  94. AP Chemistry

    In a fit of boredom, a chemistry teaching assistant swallows a small piece of solid dry ice (CO2). The 8.9 g of dry ice are converted very quickly into gas at 311 K. Assuming the TA’s stomach has a volume of 1.5 L, what pressure is exerted on his
  95. science

    Can you direct me to a site(s) which can help with college chemistry and statistics? Here are a couple of good chemistry sites that pretty well cover the waterfront. I don't know any stat sites but if you will repost with the subject line of "math" I'm
  96. Chemistry

    I have a Chemistry question which should be very simple but I do not know what significant figures are. Assuming the following numbers are measurements and using the rules for significant figures, determine the answer for the following calculation.
  97. Urgent... I need help please

    When do you think the prosecutor's office should become involved in a case (pre-arrest or post-arrest)? Do you think involvement by a prosecutor in the original stages of an investigation is a good idea? Can a defense attorney ever become involved in a
  98. chemistry+reply

    can someone reply to my previous chemistry thread please?
  99. Chemistry lab

    List 10 equipment use in the chemistry lab and their uses
  100. PLZ look at Chemistry Questions!!!

    No chemistry questions are getting answered =(