1. chemistry

    Substance x has a molar mass of 107.6 g/mol. when 2.50 g of substance x burns in an iron calorimeter the temp. of calorimeter and water (2.000Kg)increases from 25.8 d Celsius to 38.7 d celsius. What is the molar heat of combustion of substance x in kJ/mol.
  2. chemistry

    substance X has a molar mass of 107.6 g/mol. When 2.50 g of substance x burns in an iron calorimeter, the temp. of the calorimeter and the water (2.000 Kg) increases from 25.8 deg. C to 38.7 deg. C. What is the molar heat of combustion of substance X in
  3. Chemistry

    Assume that a reaction occurs in which unknown substances R and S react to form unknown substances T and U. From the information below, determine the mass of substance T that will be formed if 45.0 grams of substance R reacts with 23.0 grams of substance
  4. Chemistry

    Suppose 1.0 mol of substance A reacts with 1.0 mol of substance B. to produce 2.0 mol of substance C. In a reaction, 2.4 mol of substance A is allowed to react with 2.1 mol of substance B. What amount in moles of substance c is produced?
  5. Chemistry

    In a chemical reaction, exactly 2 mol of substance A react to produce exactly 3 mol of substance B 2A ---> 3B How many molecules of substance B are produced when 27.9 g of substance A reacts? the molar mass of substance A is 24.7 g/mol STEP 1: convert the
  6. hernandez

    find the molar enthalpy of vaporization for a substance, given that 3.21 mol of the substance absolve 28.4 kj of energy as heat when the substance changes from liquid to gas? show the work
  7. chemistry

    In a chemical reaction, exactly 2 mol of substance A react to produce exactly 3 mol of substance B. How many molecules of substance B are produced when 26.5 g of substance A reacts? The molar mass of substance A is 21.9 g/mol. Step 1: Convert the mass of A
  8. Chemistry

    If 406.6 g of a substance is dissolved in 879.1 g of cyclohexane solvent, the boiling point of the solution is 87.52 oC. Calculate the apparent molar mass (g/mol) of substance.
  9. Chemistry

    If 395.3 g of a substance is dissolved in 872.6 g of cyclohexane solvent, the boiling point of the solution is 87.38 oC. Calculate the apparent molar mass (g/mol) of substance.
  10. chemistry

    If 1373 g of a substance is dissolved in 2315 g of cyclohexane solvent, the boiling point of the solution is 87.69 oC. Calculate the apparent molar mass (g/mol) of substance.
  11. chemistry

    If 1373 g of a substance is dissolved in 2315 g of cyclohexane solvent, the boiling point of the solution is 87.69 oC. Calculate the apparent molar mass (g/mol) of substance.
  12. Chemistry

    Does anyone know how to do this problem, i can't seem to solve it. If 39.25 g of a substance is dissolved in 155.5 g of benzene solvent, the freezing point of the solution is 0.08 oC. Calculate the apparent molar mass (g/mol) of substance.
  13. Chemistry

    For the equation: deltaHrxn = qrxn / mol substance to calculate deltaH per mole what does the mol substance mean? Does this mean that you use the mm of the substance or if you already calculated the # of moles of a substance do you use that?
  14. Chemistry(Please help, thank you)

    For the equation: deltaHrxn = qrxn / mol substance to calculate deltaH per mole what does the mol substance mean? Does this mean that you use the mm of the substance or if you already calculated the # of moles of a substance do you use that?
  15. chemistry

    A certain substance has a molar heat of vaporization of 54.2 kJ/mol. How much of the substance is in a sample that requires 80.0 kJ to vaporize? Answer in units of mol
  16. PLS HELP ASAP 1 SUPER HARD & ANNOYING QUESTION

    Use the diagram to answer question 13. so substance A looks like a row of three little circles on the top and bottom all organized (total six dots). substance b is all clumped together circles and is disorganized. 13. How can substance A and B be compared?
  17. Chemistry

    If 10.0 g of substance X dissolved in 100 mL of solution, and the molarity of the solution is 1.0 M, what is the molar mass of substance X? 1000 g/mol 10 g/mol 1 g/mol 100 g/mol
  18. Science

    13.)How can substance A and B be compared? Choose all that apply. A.)The particles of substance A have more energy than the particles of substance B.*** B.)The particles of substance A are more tightly held together than the particles of substance B.
  19. Chemistry

    I had to do a lab and had to calculate the molar mass for a substance with this equation MM=Mrt/pv but we had to calculate the mass of the substance and its temperature experimently. My question is why did we have to boil the liquide in a water containing
  20. Chemistry

    Find the molar enthalpy of vaporization for a substance, given that 3.21 mol of the subtance absorbs 28.4 kJ of energy as heat when the substance changes from a liquid to a gas.
  21. chemistry

    Find the molar heat of vaporization for a substance, if 3.28mol of the substance absorbs 24.8 kJ of energy when it changes from a liquid to a gas. Answer in units of kJ/mol
  22. chemistry

    An unknown substance has a mass of 17.3 . When the substance absorbs 1.557×102 of heat, the temperature of the substance is raised from 25.0 to 45.0 . What is the most likely identity of the substance?
  23. Chem 2

    1.057 grams of a substance with a molar mass of 385.336 g/mol are dissolved in 249.92. Ther temperature for the system changes from 83.83 to 52.38 degrees C during the mixing. What is the DH(heat of solution) for this process in kJ/mol. Assume that th
  24. chemisrty

    When a substance changes from one phase to another, which of the following occurs? the substance loses or gains heat the average kenetic energy of the substance changes the temperature of a substance changes the molecular motion of a substance changes
  25. Chem- Dr bob! or GK!

    Calculate the energy that must be removed to convert substance X from a gas at 116°C to a solid -44.6°C. Assume X has a molar mass of 75.0 g/mol. ÄHvap 20. kJ/mol C(s) 3.0 J/g·°C ÄHfus 5.0 kJ/mol C(l) 2.5 J/g·°C bp 75°C C(g) 1.0 J/g·°C mp -15°C
  26. chemistry

    1)If 746.4 g of a substance is dissolved in 1723 g of benzene solvent, the freezing point of the solution is -9.19 oC. Calculate the apparent molar mass (g/mol) of substance. 2) What mass ( g ) of the solvent water should be mixed with 0.008595 L of the
  27. Chemistry

    Substance X (MW=356gm) is a weak acid. Its Ka is 1.7x10^-3. Calculate pH of725ml of the following solutions: a)Containing 0.187 mol of substance x b)containing 127gm of Substance x I have been trying to figure this problem out for hours now and do not get
  28. chemistry

    An unknown substance has a mass of 28.1 g. The temperature of the substance increases by 16.3 degrees Celsius when 176 J of heat is added to the substance. What is the most likely identity of the substance? The table lists the specific heat capacities of
  29. chemistry

    Which of the following is true of a substance with a pH of 11.0? A. The substance is an acid. B. The substance is a base. C. The substance is neutral. D. The substance is a transition metal. I think A
  30. Are these correct?

    A) How do you make 200 mL of a 0.1 M solution of a substance that has a molecular weight of 121.1 g/mol? Answer I got: 200mL = 1/0.1M x 1/(121.1g/mol) x mass of the substance. mass of the substance = 0.2L x 0.1M x 121.1g/mol=2.42g Note that my answer
  31. Chemistry

    The densities of gases A, B, and C at STP are 1.25g/L, 2.87 g/L, and .714 g/L. Calculate the molar mass of each substance. Indentify each substance as ammonia, sulfur dioxide, chlorine, nitrogen, or methane.
  32. chemistry

    2.15 g of a substance X contain 4.34 x 1022 molecules of X. Calculate the molar mass of X in g/mol.
  33. Chemistry

    My question is what is the molar mass of 1.00 mol of Li? Can you explain in detail and I have another question: What is the molar mass od 1.00 mol of Ag but if you help me with the first question, then can you just tell me to the other by myself so I can
  34. Chemistry

    A solution containing 0.750g of an unknown substance in 30.0g of cyclohexane was found to freeze at 3.1 degree Celsius. What is the molar mass of the unknown substance?
  35. Chemistry

    a) A current of 1.50 Amperes passes through a solution of AgNO3 for 3.0 hours. What mass, in grams, of silver collects on the cathode? (molar mass of silver = 107.9 g/mol) b) How many seconds would it take to collect 100 g of silver to collect on the
  36. chemistry

    1) to the nearest gram, what is the molar mass of Al2O3? 2)Br+H3O->HBr+H2O when this reaction is reversed what substance acts as an acid? what substance acts as a base ?
  37. CALCULUS

    Let y(t) denote the mass of a radioactive substance at time t.t. Suppose this substance obeys the equation y′(t)=−14y(t). Assume that, initially, the mass of the substance is y(0)=M>0. At what time does half of the mass remain? (Round your answer to 3
  38. Chemistry

    66.9 g of a substance X dissolves in enough water to make 0.428 L of a 0.68 M solution. Calculate the molar mass of X in g/mol.
  39. Chemistry

    If 0.274 moles of a substance weighs 62.5g, what is the molar mass of the substance? 62.5/0.274 = 228.1 Am I on the right track?
  40. chemistry

    Calculate the energy that must be removed to convert substance X from a gas at 115°C to a solid -50.7°C. Assume X has a molar mass of 75.0 g/mol. Specific heat capacities ΔHvap 20. kJ/mol C(s) 3.0 J/g · °C ΔHfus 5.0 kJ/mol C(l) 2.5 J/g · °C bp
  41. chemistry

    Calculate the energy that must be removed to convert substance X from a gas at 115°C to a solid -50.7°C. Assume X has a molar mass of 75.0 g/mol. Specific heat capacities ΔHvap 20. kJ/mol C(s) 3.0 J/g · °C ΔHfus 5.0 kJ/mol C(l) 2.5 J/g · °C bp
  42. chemistry

    If you have 12 moles of a substance, how many molecules do you have of that substance? Suppose the substance has a molecular weight of 342. How many grams of that substance would you have to dissolve in a liter of water to make a 12 M solution?
  43. chemistry

    2. Imagine you have two beakers. Both beakers are filled with the same amount of water. The water in both beakers is the same temperature as well. You add 50 g of Substance A to the first beaker, and 50 g of Substance B to the second beaker. After stirring
  44. science HElp

    Ph scale Which on is true A substance with ph is twice as acidic as substance with ph of 4. A subtances with ph 3 is 10 as acidic as substance with ph of 4. A substance with ph 3 twice as alkies as substances with ph 4. a substancs with ph 3 10 time alkies
  45. chemistry

    Substance A and substance B react to form substance C as described by the equation: A + B ↔ C If only substance A and substance B are placed in an enclosed vessel and allowed to react what would the reaction be?
  46. Chemistry

    An unknown substance has a mass of 16.3 g. The temperature of the substance increases by 20.1 degrees Celsius when 126 J of heat is added to the substance. What is the most likely identity of the substance? The table lists the specific heat capacities of
  47. science

    A substance that has a mass of 20g and volume of 10cm3. How much mass does one cm3 of this substance have? A substance with a mass of 125g and a volume of 25cm3. How much mass does one cm3 of this substance have? Please tell me how to do this.
  48. science

    g) Use the substances given in table 1 to calculate the volume of 270 g of aluminum. The densities of substances given: glycerol (substance a) = 0.97 g/mL isoprop (substance b) = 1.20 g/mL water (substance c) = 0.85 g/mL How would i know what the mass is?
  49. Physics

    3/2/2016 An unknown substance at a temperature of 20 degrees Celsius is warmed up to 50 degrees when water at 80 degrees is added to it. The sum of the masses of the unknown substance and water is equal to 1000grams. In another experiment, the same
  50. algebra

    A radioactive substance decays according to the formula A=A0e^kt where A0 is the initial amount of substance (in grams) A is the amount of substance(in grams) after t years k is a constant The half-life of the substance is 10 years.If we begin with 20g of
  51. Chemistry (Check)

    Part B True-False Classify each of the statements as always true, sometimes true, or never true. 1.____ST______ one mole of any gas occupies a volume of 22.4 L. 2_____NT______ for a substance of known molar mass, the number of moles of a sample can be
  52. Fluid Mechanics

    A cylinder with internal diameter of 5cm and 15 cm high is filled up with an unknown substance. The mass of the cylinder is 4.6 kg which is 300% of the unknown substance mass. Determine the density and the specific gravity of the unknown substance.
  53. chemistry

    Suppose a substance has been prepared that is composed of carbon, hydrogen, and nitrogen. When 0.1156 gram of this compound is reacted with oxygen, 0.1638 gram of carbon dioxide (CO2) and 0.1676 gram of water (H2O) are collected. Assuming that all the
  54. Chemistry

    Substances A and B, initially at different temperatures, come in contact with each other and reach thermal equilibrium. The mass of substance A is twice the mass of substance B. The specifi c heat capacity of substance B is twice the specifi c heat
  55. chemistry

    A 0.750 g sample of an unknown substance is dissolved in 20.0 g of benzene, C6H6. The freezing point of the solution is 4.53 oC. Calculate the molar mass of the substance. The normal freezing point for benzene is 5.53 oC and Kf is 5.12 oC/m.
  56. chemistry

    A 0.750 g sample of an unknown substance is dissolved in 20.0 g of benzene, C6H6. The freezing point of the solution is 4.53 oC. Calculate the molar mass of the substance. The normal freezing point for benzene is 5.53 oC and Kf is 5.12 oC/m.
  57. chemistry

    The molar heat of solution of a substance is found to be +35.34 kJ/mol. The addition of 0.20 moles of this substance to 1.5 L water initially at 55. °C results in a temperature decrease. Assume the specific heat of the resulting solution to be equal to
  58. chemistry

    Combustion of 1 mol of octane results in the formation of 8 mol of carbon dioxide (CO2) . The molar mass of octane is 114.22 g/mol, and the molar mass of carbon dioxide is 44.01 g/mol. If an engine burns 550.0 g octane as it runs, what mass of carbon
  59. chemistry

    Combustion of 1 mol of octane results in the formation of 8 mol of carbon dioxide (CO2) . The molar mass of octane is 114.22 g/mol, and the molar mass of carbon dioxide is 44.01 g/mol. If an engine burns 550.0 g octane as it runs, what mass of carbon
  60. Philosophy

    The Continental Rationalists not only articulated elaborate views on substance but also utilized substance as the foundation of their metaphysics. Nevertheless, their views on substance, though similar in some respects, differ in important ways. How do
  61. Chemistry

    1) Calculate the energy. in joules, of a photon of wavelength 1.250x 10^3 nm 2) If 3.011x 10^23 molecules have a mass of 20.04 grams, what is the molar mass of the substance? Is it 40.07g/mol? 3) 47.5g of Boron contains __________ atoms of B? Is it
  62. chemistry

    a 0.0500 mol sample of a nutrient substance is burned in a bomb calorimeter containing 2.00 x 10^2g H2O. If the formula weight of this nutrient substance is 114g/mol, what is the fuel value (in nutrient Cal) if the temperature of the water increased 5.70C
  63. English

    Select the answer that contains the correct punctuation for the following sentence. A diamond is the hardest natural substance it can scratch any other stone. A. The sentence is correct. B. ... substance, it can... C. ... substance; it can... D. ...
  64. Chemistry

    A substance releases 496kJ of heat as 2.60 moles condense from a gas into a liquid. What is the molar heat of vaporization of the substance?
  65. Chemistry 11

    A hydrate of zinc chlorate, Zn(ClO3)2 .xH2O(s) contains 21.5% zinc by mass. Find the value of x. What I've done: Molar mass of Zn: 65.409 g/mol Molar mass of Cl: 2*35.453 =70.906 g/mol Molar mass of O: 6*15.9994 =95.9964 g/mol Total molar mass of
  66. CHemistry....Please help

    1.SOLUBILITY: At 25C, the molar solubility of calcium phosphate in water is 1.1*10^{-7}M. Calculate the solubility in grams per liter. I m not sure how to convert M to g/L MOLAR MASS OF COLLIGATIVE PROPERTIES: 2.tert-Butyl alcohol is a solvent with a Kf of
  67. Chemistry

    mass-mass conversions and mass-mole conversions: what is the difference and how do you do each? mass is converted to mols by mols = grams/molar mass. mass of one chemical is converted to mass of another chemical by using the coefficients in the balanced
  68. Science

    1.Is molar mass always done for one mol of substance? Let me make up an example: 2H2(g)+O2(g)--> 2H2O When finding molar mas of water would it be 2(2(1.01)+2(16)) or just 2(1.01)+16? 2. I'm not really sure about endergonic exergonic reaction because my
  69. Chemistry

    Do the following parameters indicate how stable a substance is? 1) Viscosity of a substance 2) Optical rotation of a substance
  70. chemistry

    what is the density of a substance if a 2.50 ml sample has a mass of 0.880g at room temperature? what is the specific gravity of the substance?
  71. Chemistry

    A substance has the following properties: Heat capacities: 1.34 J/g oC (solid) 3.02 J/g oC (liquid) 2.55 J/g oC (gas) Heat of Fusion = 4.23 kJ/mole Heat of Vaporization = 23.5 kJ/mole Boiling Point = 88.5 oC Melting Point = -30.0 oC Molar Mass = 96.3
  72. Physics 2

    An unknown substance has a mass of 0.125 kg and an initial temperature of 98.0°C. The substance is then dropped into a calorimeter made of aluminum containing 0.285 kg of water initially at 30.0°C. The mass of the aluminum container is 0.150 kg, and the
  73. Chemistry

    A 0.120 g sample of a diprotic acid of unknown molar mass is dissolved in water and titrated with 0.1218 M NaOH. The equivalence point is reached after adding 12.4 mL of base. What is the molar mass of the unknown substance?
  74. 9th grade

    An uknown substance from planet x has a density of 10g/ml.it occupies a volume of 80ml. what is the mass of this unknown substance
  75. 9th grade

    An uknown substance from planet x has a density of 10g/ml.it occupies a volume of 80ml. what is the mass of this unknown substance
  76. Math

    The density of a substance A rectangular s given as 13.6 g/cm^3 and that of a substance B as 11.3 g/cm^3. Determine the volume of B that would have the same mass as 50 cm^3 of A.
  77. psychology

    1 which statement most accurately differentiates substance dependence from substance abuse? A substance dependence involves ongoing use of a drug despite the problems it causes in the person's functioning. B With substance dependence, the individual uses
  78. chemistry

    Substance X has a molar extinction coefficient (E) of 4725 l.mol-1 cm-1. How many micromoles of X are needed to produce an absorbance of 1.0 in a 1 ml cuvette?
  79. cor biology

    Substance X has a molar extinction coefficient (E) of 4725 l.mol-1. How many moles of X are needed to produce an absorbance of 1.0 in a 1 ml cuvette?
  80. Exponential Modeling

    The half-life of a radioactive substance is one day, meaning that every day half of the substance has decayed. Suppose you have 100 grams of this substance. How many grams of the substance would be left after a week?
  81. Math

    A radioactive substance decays according to the formula Q(t) = Q0e−kt where Q(t) denotes the amount of the substance present at time t (measured in years), Q0 denotes the amount of the substance present initially, and k (a positive constant) is the decay
  82. Math

    A radioactive substance decays according to the formula Q(t) = Q0e−kt where Q(t) denotes the amount of the substance present at time t (measured in years), Q0 denotes the amount of the substance present initially, and k (a positive constant) is the decay
  83. Chem

    Substance X raises the boiling point of 150g of water to 101.3 C. What is the molecular mass of substance X? (assume x does not ionize/ is not volatile)
  84. Chemistry

    Consider the following properties of a particular substance: melting point: -7.2 degrees C boiling point: 58.8 degrees C heat of fusion: 10.571 kJ/mol specific heat of the solid: 87.4 J/mol degrees C specific heat of the gas: 40.0 J/mol degrees C specific
  85. Science

    Radioactive substance decays so that after t years, the amount remaining, expressed as a percent of the original amount, is A(t)=100(1.6)^(-t). a) Determine the function A’, which represent the rate of decay of the substance. b) what is the half-life for
  86. Chemistry

    A forensic scientist is given a white substance that is thought to be cocaine. The substance is found to have a percent composition: 49.48% C, 5.19% H, 28.85% N, and 16.48% O. What is the empirical formula for this substance? Is it cocaine?
  87. EMpirical and Molecular Formula

    A forensic scientist is given a white substance that is thought to be cocaine. The substance is found to have a percent composition: 49.48% H, 5.19% H, 28.85% N, and 16.48% O. What is the empirical formula for this substance? Is it cocaine?
  88. Physics

    The graph shows the temperature versus time relationship for 2 kg of particular substance. The substance is in the solid state at a room temperature of 20 degrees Celsius. - The 100 joules of heat is needed to completely change the substance from a solid
  89. Physics

    The relative density of a solid is 6.5. Find (1)the mass of a solid substance cube of side 20cm. (2) the volume of the substance if the mass is 1.3kg
  90. College Chemistry

    A 43.70 g sample of a substance is initially at 24.7 °C. After absorbing 1757 J of heat, the temperature of the substance is 120.5 °C. What is the specific heat (c) of the substance?
  91. Pam

    A 56.59 g sample of a substance is initially at 20.5 °C. After absorbing 1267 J of heat, the temperature of the substance is 116.5 °C. What is the specific heat (c) of the substance?
  92. algebra

    Julie has 250 grams of a radioactive substance. The substance decays every hour. How long will it take until she has 20 grams of the substance left?
  93. chemistry

    given 10.8 grams of substance y,if the substance absorbs 231 kilojoules of energy and the specfic heat of substance is 6.55 J/g*0C what is the heat change
  94. chemistry

    How would you find the empirical formula for this... a substance was found by analysis to contain 20% by mass calcium and 80% by mass bromine. Would it be CaBr2? This is what I did... 50g Ca * 20 mol Ca/801.56g Ca = .499 mol Ca 80g Br * 80 mol Br/6392.32g
  95. chemistry

    10.0mL of a pure liquid substance has a mass of 25.0 g. What is the mass of 3.00 L of the substance?
  96. AP Chemistry

    A 5 gram sample of a gaseous substance occupies 10 L at 48◦C and 697 torr. What is the density of the gas under these conditions? Answer in units of g/L I first started converting the temperature to Kelvin, and the pressure to ATM. I then re-arranged the
  97. Calculus-derivatives

    Verify if these are correct answers. 1. The derivative of f(x)=e^2x -e^-2x is f'(x)=2e^2x - 2e^-2x? 2.A certain radioactive substance is decaying so that at time t, measured in years, the amount of the substance, in grams, given by the function
  98. Chemistry

    Construct a cooling curve (looks the same as a heating curve) for a substance with a molar mass of 200 that has a gas phase specific heat capacity of 2.9J/g K, a boiling point of 525 K,a liquid phase specific heat capacity of 3.24 J/g K, a freezing point
  99. Math

    Each ounce of a substance A supplies 2% of the nutrition a patient needs. Substance B supplies 15% of the required nutrition per ounce, and substance C supplies 15% of the required nutrition per ounce. If digestive restrictions require that substances A
  100. Math

    Each ounce of a substance A supplies 2% of the nutrition a patient needs. Substance B supplies 15% of the required nutrition per ounce, and substance C supplies 15% of the required nutrition per ounce. If digestive restrictions require that substances A