1. Chemistry

    a sample of a compound with a mass of 0.4168g is extracted from a plant. Decompostion of this sample produces 0.1667g of carbon, 0.2223g oxygen, and the remainder is hydrogen. What is the percentage compostion (by mass) of the compound?
  2. Chemistry

    In a body of fresh water, a dissolved oxygen concentration of 0.262 or higher is usually needed to maintain a healthy aquatic ecosystem. For a lake to maintain this concentration, what is the maximum water temperature?
  3. Chemistry

    Assume that some of the magnesium nitride is not completely converted to magnesium hydroxide and subsequently to magnesium oxide. Will your empirical formula be too high in magnesium or too high in oxygen? Please show any calculations you used to determine
  4. CHEM

    Calculate the density of oxygen, , under each of the following conditions: STP 1.00atm and 25.0 degrees celsius Express your answers numerically in grams per liter. Enter the density at STP first and separate your answers by a comma.
  5. Chemistry

    In the explosion of a hydrogen-filled balloon, 0.80g of hydrogen reacted with 6.4g of oxygen. How many grams of water vapor are formed? (Water vapor is the only product.) Express your answer using two significant figures.
  6. Science

    Does anyone know anything about respiration?? Cause I have to do this chart thing and it says: Respiration uses glucose and oxygen to produce carbon dioxide and water and water is used to carry out all _________. I don't know what the blank is I have read
  7. Chemistry

    In a body of fresh water, a dissolved oxygen concentration of 0.262 or higher is usually needed to maintain a healthy aquatic ecosystem. For a lake to maintain this concentration, what is the maximum water temperature?
  8. Chemistry (Check)

    Nitrogen combines with oxygen to form a variety of compounds. One of these compounds is called nitrous oxide or "laughing gas." What is the formula of nitrous oxide if this compound is 63.65% N and 36.35%O by weight? I got N2O
  9. Chem Help

    In body of fresh water, a dissolved oxygen concentration of 0.225 mM or higher is usually needed to maintain a healthy aquatic ecosystem. For a lake to maintain this concentration, what is the maximum water temperature?
  10. ap chemistry

    Carbon monoxide reacts with oxygen to form carbon dioxide by the following reaction: 2CO(g) + O2(g) ! 2CO2(g) H for this reaction is −135.28 kcal. If 811.7 kcal is released, how many moles of CO must have reacted?
  11. business law

    mark was a muktihandicapped student needing special education. mark parnets and the school board signed ann agreement that required the board to pay the placement costs for mark at a residential school. the Bemedoctome school at the current annual rate of
  12. chem

    Maleic acid is an organic compound composed of 41.39% C, 3.47% H, and the rest oxygen. If 0.250 mol of maleic acid has a mass of 29.0 g, what are the empirical and molecular formulas of maleic acid?
  13. Chemistry

    For the reaction HCl + NaOH → NaCl + H2O, how many moles of hydrochloric acid are required to produce 281.0 g of water?
  14. physics (urgent)

    A flywheel with a moment of inertia of 1.00kg m^2 is rotating at 100 rpm. What torque is required to bring it to rest in 10.0 revolutions?
  15. AP CHEMISTRY NEED HELP PLEASE

    What Volume of nitrogen at STP would be required to react with 0.100 mol of hydrogen to produce ammonia? N2(g) +3H2 (g)(arrow) 2NH3(g)
  16. Chemistry

    Determine the number of grams of water which are required to dissolve a mixture of 25 g of KNO3 and 2.0 g of CuSo4 * 5H20 AT 100 Degrees celscius?
  17. Calculus

    Determine how much time, to the nearest tenth of a year, is required for an investment to triple in value if interest is earned at the rate of 3.5% compounded continuously. (use A=Pe^rt
  18. math,physics,chemisty,biology

    the number of moles of H2O2 required to completely react with 400ml of 0.5N KMnO4 in acidic medium are
  19. owning

    _________of the vehicle is the likely consequence of failture to make the required loan payments. A.Theft B.Repossession C.Destruction D.Loss of warranty i got D
  20. Chemistry

    What minimum volume of 3.0 M H2SO4 is required to produced 13 L of H2 at STP? Reaction formula: 2Al(s) + 3H2SO4(aq) --> Al2(SO4)3(aq) + 3H2 (g)
  21. Math

    Rectangular courtyard is 57m 50cm and 22m broad. Determine the least possible number of square stones of the same size required to pave it.
  22. Biochemistry

    What volumes of 25 mM CH3COOH and 25 mM NaCH3COO are required to prepare 300 mL of a 0.25 M buffer of pH = 5.0? (pKa = 4.76) I keep getting something along the lines of 19ml for the conj. base..I know that's way wrong. help please!
  23. phys chem

    how much energy (kj/mol) is required to break the hydrogen bond in water (Er=80.0) (Er= Relative permitivity) I'm really not sure how to approach this, and if i need enthalpies of vaporization or not...
  24. Chemistry

    Can anyone answer this question please. (Determine the concentration of an aqueous NaCl solution if 31.5 mL are required to reach the equivalence point when titrated with 25.0 mL of 0.20 M AgNO3.)
  25. physics

    The coefficient of kinetic friction for a 25 -kg bobsled on a track is 0.10.What force is required to push it down a 6.0^\circ incline and achieve a speed of 67 km/h at the end of 75 {\rm m}?
  26. College Physics

    Find the minimum work required to carry a truckload of furniture weighing 1.99 104 N to a third-story apartment, 24.0 m above the truck.
  27. Physics

    What is the angular momentum of a 2.4 kg uniform cylindrical grinding wheel of radius 12 cm when rotating at 1800 rpm? How much torque is required to stop it in 4.0 s?
  28. mgmt 303

    some people have claimed that the increasing technological sophistication required by many of today's corporations has led to a return to job specialization.
  29. Chemistry

    How much energy (in kilojoules) is required to convert 130mL of diethyl ether at its boiling point from liquid to vapor if its density is 0.7138 g/mL?
  30. Chemistry

    3NO2 + H2O = 2HNO3 + NO How many grams of nitrogen dioxide are required to produce 5.89 x 10 to the 3rd power kg HNO3 in excess water?
  31. Physics

    A jack has a lever arm of 45cm and pitch of 0.5cm. If it's efficiency is 30%,what force is required to lift a load W of mass 1200kg
  32. PHYSICS

    What is the angular momentum of a 2.7 kg uniform cylindrical grinding wheel of radius 12 cm when rotating at 1600 rpm? How much torque is required to stop it in 4.4 s?
  33. Physics

    A 600kg car is moving on a level road at 30m/s.how large is a retarding force is required to stop it in a distance of 70m
  34. Calculus

    For the function f(x) = x/(3x+1) find the equation of the line which is tangent to the curve f(x) at x=2. Solve analytically (an exact answer is required) Please show steps. Thanks.
  35. chemistry

    The volume of 0.15 mol dm ^-3 sulphuric acid,H2SO4 required to completely neutralise 25.0cm^3 of potassium hydroxide,KOH solution.
  36. Chem 2 Lab

    Calculate the volume of a 0.150 M NaOH solution that will be required to neutralize all of the H+ ions in 0.400 grams of phosphoric acid?
  37. chemistry

    The question is how many kilojoules are required to melt 24g of ice at 100 degrees celsius? Can you please correct me if im wrong. ( Which I'll probably will be ) I did: 24 x 333= 800kj
  38. Math

    Scores on a marketing exam are known to be normally distribute with mean and standard deviation of 60 and 20, respectively. The syllabus suggests that the top 15% of the students will get an A in the course. What is the minimum score required to get an A?
  39. gRammar

    Proofread the following sentences. Insert punctuation as required. After a Maylard incision was made through the abdomen a retractor was used for visualization of the pelvic contents.
  40. english

    what lifestyle changes were required by ordinary americans or teenagers during world war 2? please help me to find info about this topic for my short research report.
  41. math

    a rectangular courtyard is 57m 50cm long and 22 m board . determine the least possible number of square stones of the same size required to pave it ?
  42. physics

    if you wished to warm 100 kg of water by 15 degrees celsius for your bath, how much heat would be required? (give your answer in calories and joules)
  43. chemistry

    the quantity of electricity required to reduce 12.3g of nitrobenzene to aniline assuming 50% current efficiency is 1. 115800 C 2. 57900 C 3. 231600 C 4. 28950 C
  44. Math

    Hi everyone! May anyone please tell me how to tell how many zeroe's are required in your answer when moving the decimal points in converting metric units? Thank you very much! PLease help son, if possible, as I have a really big test coming up!
  45. Chem 101

    Using the "Unit conversion method", derive an equation to calculate the heat required to raise the calorimeter to the maximum temperature.
  46. geometry

    afence is to be built on the diagnal of a rectangular dog park which is 250ft by 200ft to the nearest tenth of a foot. how much fence will be required?
  47. chemistry

    What volume of 0.050 M AgNO3, silver nitrate solution is required to reat completely with 60.0 mL of 0.025 M K2S, potassium sulfide?
  48. PHYSICS

    Calculate a constant force required to bring an object of mass 2.0kg.moving with a velocity of 4.0m/s to rest in. 0.1sec and 2metre
  49. Mechanics

    Calculate the average horsepower required to raise a 200-kg drum to a height of 20 in a time of 1:0 minute. Show the solution and answer
  50. Math

    A rectangular courtyard is 57m 50 cm long and 22m broad. Determine the least possible number of square stones of the same size required to pave it
  51. chemistry

    Calculate the total amount (in moles) of Ca and Mg present in a sample of water that required 12.86 ml of 0.0005M EDTA solution to completely complex them.
  52. chemistry

    How much Tris-Acetate-EDTA (TAE) stock buffer (3.25 M) is required to make 400 ml of solution that has a concentrations of 250 mM? How much water?
  53. history

    what lifestyle changes were required by ordinary americans or teenagers during world war 2? please help me to find info about this topic for my short research report.
  54. chemistry

    20.0 g of CH3OH is frozen solid at -98.0 degrees C. What is the total energy required to melt it, warm the liquid to its boiling point, and then just vaporize it?
  55. Chemistry

    What is the molar mass of 0.500 g of unknown monoprotic acid used in titration, if 22.5 mL of 0.15 M NaOH solution was required to neutralize it? I do not need the answer, but instead an example of how to do a question just like it.
  56. accounting

    I am stumped on my last question which is using the discounted cash flow formula.... what effect will increase the required rate of return on the present value. I'm getting that it will be increased. Is this right?
  57. Math

    A rectangular courtyard is 57m 50 cm long and 22m broad. Determine the least possible number of square stones of the same size required to pave it
  58. Chemistry

    What volume in mL of .100 M NaOH would be required to titrate a 297 mg sample of a weak acid with an equivalent weight of 126 grams?
  59. physics

    An automobile manufacturer claims that its product will travel 1.2 km in 27 s, starting from rest. What is the magnitude of the constant ac- celeration required to do this? Answer in units of m/s2.
  60. Chemistry

    Calculate the number of milliliters of 0.782 M KOH required to precipitate all of the Mn2+ ions in 112 mL of 0.461 M Mn(NO3)2 solution as Mn(OH)2.
  61. Chemistry (Acid&Base)

    How many mL of 0.203 M HCl(aq) are required to prepare a diluted solution that has a concentration of 0.0433 M in a 100-mL volumetric flask?
  62. Physics

    A corvette can go from 0~60 mph in 4.3 seconds. If the mass of the car is 1443 kg how much work is required to complete this task (assuming it is on a horizontal road)?
  63. international business

    4.Why is acceleration or delay of payments more useful to an IC than to smaller, separate companies? i was able to answer all but this question. i have read the material required but i don't quite get what they are asking?
  64. Chemistry

    If the CO2 is not removed by boiling after the addition of HCL, how will this affect the amount of NaoH required to reach the bromophenol endpoint. Explain.
  65. physics

    What is the required resistance of an immersion heater that will melt 6.39 kg of ice at 0°C in 36 min while operating at 110 V? im not too sure how to do this because delta_T=0. With the equations im using, i get 0 but its not the answer and im not quite
  66. Chemistry

    what is the specific heat of an unknown substance of 2000 j of energy required to raise the temperature of 4 grams of substances 5 degrees celsius
  67. Economics

    How will a new law mandating an increase in required levels of automobile insurance affect the equilibrium price and quantity in the market for new automobiles?
  68. Intermediate Macroeconomics

    If the required reserve ratio is 12% and total reserves increase by $100, what is the maximum amount by which the money supply can expand?
  69. Chemistry

    What mass of MgSO4 · 7H2O is required to prepare 800 mL of a 0.442MMgSO4 solution? Answer in units of g. Would you use the formula M1V1=M2V2?
  70. Physics

    an aircraft lands on a runway with length of 205 m at a speed of 295 km/h what is the minimum constant deceleration required for a safe landing
  71. math

    A rectangular courtyard is 57m 50 cm long and 22m broad. Determine the least possible number of square stones of the same size required to pave it
  72. finace

    _________ of the vehicle is the likely consequence of failure to make the required loan payments. A. Theft B. Repossession C. Destruction D. Loss of warranty
  73. EDU

    What is the importance of the Ole Deluder Satan Act? Why was it made? I know that required that towns with 50 or more families establish schools, but what is the connection with the school system?
  74. IT

    What steps would you take in diagnosing an application that has been changed from its original state? How does this affect the level of support required to facilitate Microsoft® Access® users?
  75. Chemistry II

    Determine the grams of solute required to prepare 0.5 m solution HC2H3O containing 750 g of water. Make sure to show your work. **(Thanks for helping by the way.)**
  76. physics

    What is the angular momentum of a 2.43 kg uniform cylindrical grinding wheel of radius 12.5 cm when rotating at 1600 rpm? (b) How much torque is required to stop it in 8.00 s?
  77. math

    A rectangular courtyard is 57m 50 cm long and 22m broad.Determine the least possible number of square stones of the same size required to pave it.
  78. science

    Octane (C8H18) is a liquid that combusts with oxygen gas (O2) to form water (H2O) and carbon dioxide (CO2). Write a balanced chemical equation for this reaction and explain the scientific principle (statement) that requires the balancing of an equation to
  79. chem

    write a balanced equation for:Gaseous carbon dioxide and liquid water react to produce aqueous glucose (C6H12O6) and oxygen gas. I try but everytime i change the coefficient it makes the other elements unbalanced. the starting formula i got was: CO2(g) +
  80. chemistry

    Potassium nitrate is made by adding potassium chloride to hydrogen nitrate in the presence of oxygen gas. Along with the potassium nitrate, chlorine and water are produced. How would write the equation?
  81. Physics

    Find the jet fuel mileage (mpg) of a Boeing 787 Dreamliner if: C=0.024, v=900 km/h, 1 gallon=3.8 liters, 1 mile= 1.6 km, energy conversion efficiency=30%, A=2060 ft^2, 1 ft^2=0.093 m^2, drag force = 1/2(CApv^2), p=0.41 kg/m^3 at 10,000 m, jet fuel energy
  82. math (unit rate)

    Find the unit rate. $121.50 for working 18 hours wages = hourly rate x time 121.50 = hourly rate x 18 hours. Solve for hourly rate. how do i solve for hourly wages = hourly rate x time 121.50 = hourly rate x 18 hours. You want to get hourly rate by itself.
  83. Programming

    How would the flow charts and pseudocode look for this? The Metric Conversion application is a menu-driven program. First, the program displays a Main Menu that states the purpose of the program and allows the user to select one of five metric system
  84. Physics

    Kim(55 kg) has been wondering about the normal force. (a) How many helium balloons would it take to reduce her normal force by 50% if helium has a lifting force of 1.0 gram per liter. She estimates that a balloon contains about 5.0 liters of helium. (b)
  85. programming

    please Help... Write a pseudo code that prompt the driver to enter the miles at the before taking the car and miles when returning the car.the program must him to enter the fuel consumed that day.the must be able to determine the fuel consumption for that
  86. Steve help please?!?!

    How many moles of oxygen are produced from the decomposition of 36.7 g of dinitrogen pentoxide? 2N2O5 4NO2 + O2 A. 3.19 mol B. 0.340 mol C. 0.170 mol D. 5.44 mol Hi Steve, I posted this question the other day but really don't know how to answer it. Can you
  87. Chemistry

    2 B5H9(l)+12 O2(g)---->5 B2O3(s)+9 H2O(l) Calculate the kilojoules of heat released per gram (kJ/g) of the compound reacted with oxygen. The standard enthalpy of formations of B5H9(l), B2O3(s), and H2O(l) are 42.84, -1271.94, and -285.83 kJ/mol,
  88. chemistry

    ogen and oxygen react to form nitrous oxide as: 2 N2 (g) + O2 (g) ⇌ 2 N2O (g) Of a mixture of 0.482 mol N2 and 0.933 mol O2 is placed in a reaction vessel of 10.0 L and allowed to from N2O at a temperature for which Kc = 2.0 X 10-37, what will be the
  89. chem

    When NH3 is treated with oxygen gas, the products obtained are N2(g) and H2O(l). If standard enthalpies of formation at 298 K for NH3(g) and H2O(l) are –46.00 kJ/mol and –286.0 kJ/mol respectively, calculate the enthalpy change of the reaction.
  90. chemistry

    When NH3 is treated with oxygen gas, the products obtained are N2(g) and H2O(l). If standard enthalpies of formation at 298 K for NH3(g) and H2O(l) are –46.00 kJ/mol and –286.0 kJ/mol respectively, calculate the enthalpy change of the reaction.
  91. Chemistry

    A compound containg 3 atoms of carbon and 8 atoms of hydrogen is combined in a reaction with oxygen molecules. The two end products of this equation are carbon dioxide (CO2) and water. What element should you look at first in balancing this equation?
  92. Chemistry

    Liquid methanol (CH3OH) is combusted in oxygen gas to yield carbon dioxide gas and liquid water Okay I keep getting this: CH3OH(l) + 1.5 O2(g) > CO2(g) + 2 H2O(l) the website tells me I'm wrong, but I don't know how to go about with out using fractions.
  93. chemistry calculations

    when 2.750 g of the oxide of lead is heated to a high temperature,it decomposes to produce 0.0640 g of oxygen gas and 2.686 g of some new lead oxide compound.How can you use this data to determine the formula of the new compound?
  94. chemistry

    The activation energy for the reaction in which CO2 decomposes to CO and a free radical oxygen atom, O, has activation energy of 460 kJ mol^-2. The frequency factor is 2 x 1011 s^-1. What is the rate constant for this reaction at 298 K?
  95. chem

    Liquid carbon disulfide reacts with 415 mL of oxygen to produce the gases carbon dioxide and sulfur dioxide. What volume of carbon dioxide is produced? Answer in units of L
  96. chemistry

    How many moles of chlorate ions, zinc ions, and oxygen atoms are present in 0.433 mol of zinc chlorate?
  97. Chemistry

    write the formula for hydrogen and bromine forming hydrogen bromide & nickel and oxygen forming nickel (II) oxide
  98. chemistry.

    A chromium compound 28.4% by mass of sodium 32.1% by mass of chromium, the rest being oxygen. Determine the empirical formula of the compound?...Can any one help me for that?
  99. biology

    snail in the low oxygen environment what aspects of the new environment will be salient snail and how will aspects act as selective forces
  100. Intro to Chem

    24.3 g of magnesium yield 40.3 g MgO upon combustion with oxygen. How much magnesium needs to be burned to yield 12.1 g MgO? Please help! I can't figure this out. Little guidance here!