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Chemistry

  1. A 0.5224g sample of an unknown monoprotic acid was titrated with 0.0998M of NaOH. The equivalence point of the titration occurs at 23.82 mL. Determine the molar mass of the unknown acid.

  2. For which of the following aqueous salts will electrolysis produce hydrogen gas and oxygen gas? Answered the hint in Mastering Chem & looked over the book and I still have no idea.

    Check all that apply: A) NiF_2(aq) B) NaF(aq) C) NiI_2(aq) D) NaI(aq) E)

  3. write the balanced equation for the ionization of the weak base pyridine, C5H5N, in water

  4. Indicate how each of the following would affect the value of the absorbance (too high, too low, or not effect) of the indicated solution.

    I really need help. I do not understand these questions! This is from a chemistry activity to determine the unknown

  6. How would I find the volume occupied by 3 moles of N2 at zero degrees and 101.325 kPa?

  7. The Ksp of PbBr2 is 6.60× 10^–6.

    What is the molar solubility of PbBr2 in pure water? What is the molar solubility of PbBr2 in 0.500 M KBr solution? What is the molar solubility of PbBr2 in a 0.500 M Pb(NO3)2 solution?

  8. An aqueous solution is 8.50% ammonium chloride, NH4Cl, by mass. The density of the solution is 1.024g/mL. Calculate the molality, mole fraction, and molarity of NH4Cl in the solution.

    I know the formulas needed but I'm not sure where to start. M = moles

  9. if i place C6H14 and KI in a test tube, then some metal salt (MNO3) is added...

    If the M+ reacts with and oxidizes the I, What color is c6h14? I think its purple.. but im not sure why it would be that color .. :S .. care to explain please ? and if it doesnt

  11. The primary goal of water-softening ion exchange systems is _____ (1 point)

    A removing magnesium and calcium from water. *** B removing sodium from water. C introducing magnesium and calcium into water. D introducing sodium into water. How does a reverse

  12. If 50.0 g of silicon dioxide is heated with an excess of carbon, 27.9g of silicon carbide is produced.

    SiO2(s) + 3C(s) --> SiC(s) + 2CO(g) what is the percent yield of this reaction?

  13. What is the maximum mass, in grams, of NH3 that can be produced by the reaction of 1.0 g of N2 and 1.0 g of H2 using the reaction below?

    N2+H2→NH3 (not balanced) A) 0.60 g B) 5.7 g C) 1.2 g D) 2.9 g

  14. Sodium methanoate, NaHCOO, and methanoic acid, HCOOH, can be used to make a buffer solution. Explain how this combination resists changes in pH when small amounts of acid or base are added.

    Buffers kind of confuse me and I'm not sure how to start this. Can

  16. Carbon dioxide gas has a solubility of 0.0972 g/100 g H2O at 40 degrees celsius. Expressed in parts per million, this concentration is closest to...

    (1)0.972 ppm (2)9.72 ppm (3)97.2 ppm (4)972 ppm

  17. Suppose that a 10-mL sample of a solution is to be tested for Cl- ion by addition of 1 drop (0.2mL ) of 0.15 M AgNO3 .

    What is the minimum number of grams of Cl- that must be present in order for AgCl(s) to form?

  18. For the following reaction, Kp = 3.5 104 at 1495 K.

    H2(g) + Br2(g) 2 HBr(g) What is the value of Kp for the following reactions at 1495 K? (a) HBr(g) 1/2 H2(g) + 1/2 Br2(g) (b) 2 HBr(g) H2(g) + Br2(g) (c) 1/2 H2(g) + 1/2 Br2(g) HBr(g)

  19. A gas sample at STP contains 1.15 oxygen and 1.55g nitrogen. What is the volume of the gas sample?

    the answer 2.04. I want to know how to get the that answer

  21. What is the mass in grams of copper chloride dihydrate (CuCl2·2H2O) required to prepare 80.0 mL of a 0.10 M CuCl2 solution?

  22. "Calculate the enthalpy of vaporization of water given that, when 5.00 grams of steam (gaseous H2O) at 100°C was introduced into a beaker containing 500 grams of water at 20.0°C, the temperature rose to 26.2°C."

    q_H2O(l) + q_H2O(g)= E nΔH_vap +

  23. What volume of .1 N KMnO4 would be required to titrate .56g of K2[Cu(C2O4)2] 2H20? So, my problem is the normality thing and I need a general direction to go in if possible. From my research, the .1 N means that 1/10 of a mole of KMnO4 is dissolved. I know

  24. The Ka values of H3PO4 are shown below.

    Ka1 7.5 10-3 Ka2 6.2 10-8 Ka3 4.8 10-13 What is the pH of a 0.19 M solution of NaH2PO4?

  26. Heres the question:

    "In determining the simplest formula of lead sulfide, 2.46 grams of lead are placed in a crucible with 2.00 grams of sulfur. When the reaction is complete, the product has a mass of 3.22 grams. What mass of sulfur should be used to in

  27. A direct-current power supply of low voltage (less than 10 volts) has lost the markings that indicate which

    output terminal is positive and which is negative. A chemist suggests that the power supply terminals be connected to a pair of platinum electrodes

  28. The specific heat of solid silver is 0.237 J/g degrees celsius and the heat of fusion of silver at its melting point of 961 degrees celsius is 11 J/g. Find the final temperature is 1490 J is used to heat 40 g of silver initially at 20 degrees celsius.

    Answe

  29. Which of the following represents a pair of isotopes?

    Atomic Number Mass Number a. I 7 16 II 8 16 b. I 17 34 II 18 36 c. I 17 35 II 17 37 d. I 7 14 II 8 16 e. I 17 37 II 18 37

  31. OOPs i Meant How many grams CaCo3will dissolve on 3.0*10^2mL of 0.050 M Ca(NO3)2? Ksp=8.7*10^-9

  32. You have 23.0g of water initially at -46°C. How much energy in joules is required to

    heat the ice to 0°C? c ice = 2.1 J/g°C. I thought joules was calculated by grams*change in temperature*specific heat. The answer I get from 23*46*2.1 is 2221.8, but web

  33. Use an enthalpy diagram to calculate the lattice energy of CaCl2 from the following information. Energy needed to vaporize one mole of Ca(s) is 192 kJ. For calcium, the first IE = 589.5 kJ mol-1, the second IE = 1146 kJ mol-1. The electron affinity of Cl

  34. Which of the following illustrates an everyday-life example of how london forces are induced?

    A. The attraction of an object to earth through gravity B. The attraction of a magnet with a metal object C. The attraction of your hair in a balloon after the

  36. Which fact is true during a fission chain reaction?(1 point)

    A) The total number of protons will decrease over time. B) The total number of protons will increase over time. C) The number of freely-moving neutrons decreases over time. D) The number of

  37. A solution formed by dissolving an antacid tablet has a pH of 9.18. Calculate [H+].

  38. The rusting of iron is represented by the equation 4Fe+3O2=2Fe2O. A 1.45-mol sample of iron, how many moles of Fe2O3 will there be after rusting has completed.

  39. When 0.100 mol of carbon is burned in a close vessel with 8.00g of oxygen, how many grams of carbon dioxide can form? Which reactant is in excess, and how many grams of it remain after the reaction?

  41. A rxn has delta H ^0 rxn=-112kj and delta S^0 rxn =354 J/K. at what temp is the change in entropy for the rxn equal to the change in entropy for the surroundings?

  42. The energies, E, for the first few states of an unknown element are shown here in arbitrary units:

    n= 1, E=-21 n=2, E=-9 n=3, E=-4 n=4, E=-3 ...,... infinity, 0 A gaseous sample of this element is bombarded by photons of various energies (in these same

  43. Calculate the mass of cacl2 formed when 5 moles of chlorine reacts with calcium metal

  44. How Many Moles Of H2O Are Required To Produce 4.5 Moles Of HNO3 According To The Following Reaction: 3NO2+H2O = 2HNO3+NO

  46. A Balanced equation to represent the reaction between 1-pentanol and ethanoic acid. (Production of an ester)

  47. Butyric acid (HC4H7O2) is a weak acid with the stench of rancid butter

    1.) write the equation for the dissociation of HC4H7O2 in water 2.)the pH of .5 M HC4H7O2 is 2.56 calculate Ka of butyric acid 3.) Write the equation for the hydrolysis of C4H7O2- 4.)

  48. Cell Potential at Equilibrium

    For a single galvanic cell based on the (unbalanced) reaction: Ag+(aq) + Zn(s) = Zn2+(aq) + Ag(s) What is the cell potential when the cell reaches equilibrium?

  49. A 0.60mol sample of PCl3(g) and a 0.70mol sample of Cl2(g) are placed in a previously evacuated 1.0L rigid container, and the reaction represented above takes place. At equilibrium, the concentration of PCl5(g) in the container is 0.040M

    A. Draw three

  51. What mass of aluminum is deposited electrolytically in 30 minutes by a current of 40A?

  52. If 25.00 mL of 6.00 M HCl is transferred by pipet into a volumetric flask and diluted to 5.00 L, what is the molarity of the diluted HCl?

    a) 0.75 M b) 0.055 M c) 1.20 x 103 M d) 48.0 M e) 0.0300 M grams of solute/molar mass of solute/liters of solution?

  53. (Ksp= 5.0*10^-13)

    1) Calculate the molar solubility of AgBr in 3.0×10^−2 M AgNO3 solution. 2) calculate the molar solubility of AgBr in 0.10 M NaBr solution. I tried solving using this the quadratic formula, but it didn't work. I started with these

  54. 2. Suppose that the amount of algae in a pond doubles every 4 hours. If the pond initially contains 90 pounds of algae, how much algae will be in the pond after 12 hours?

    A.)720 pounds B.)360 pounds C.)1,440 pounds D.)114 pounds I think the answer is D.

  55. Wine is approximately 12% ethanol (CH3CH2OH) by volume. Ethanol has a molar mass of

    46.06 g/mol and a density 0.789 g/mL. How many moles of ethanol are present in a 750-mL bottle of wine?

  56. How many liters of sulphur trioxide are formed when 4800cm3 of sulphur dioxide is burned in air?

  57. How many kilojoules of heat are required to melt a 10.0 g popsicle at 0 degress C? Assume the popsicle has the same molar mass and heat of fusion as water.

    Could someone tell me what equation to use to solve this or the steps? Thank You.

  58. HNO2(aq)+NH3(aq)⇄NH4+(aq)+NO2−(aq)

    Kc=1×10^6 Nitrous acid reacts with ammonia according to the balanced chemical equation shown above. If 50.mL of 0.20MHNO2(aq) and 50.mL of 0.20MNH3(aq) are mixed and allowed to reach equilibrium at 25°C , what is the

  59. The Ksp of calcium hydroxide, Ca(OH)2, is 4.68 x 10-6 at 289.15K. Calculate the pH of a saturated solution.

    Here's my work: 4.68 x 10-6= 4s^3 s= 0.0105 -log(0.0105)= 1.98 14-1.98=12.02 The answer is supposed to be 12.324, but I'm not sure what I'm doing

  60. I dont quite understand how to find out if it's capable of reducing/oxidizing. My understanding is we check each potential and identify which is reduce = highest potential, oxidize = lowest potential.

    These are my predictions: yes Is Fe2+(aq) capable of

  61. Aluminum sulfate reacts with calcium hydroxide (from lime) to form aluminum hydroxide and calcium sulfate. Write the balanced formula unit equation for the reaction.

  62. When pure sulfuric acid is dissolved in water,heat is evolved.To a calorimeter containing 300g of water at 20degree C,10.65g of sulfuric acid also added at the same temperature.The change in temperature,which was monitored by a digital probe with

  63. A student mixes 5.0 mL of 0.00200 M Fe(NO3)3 with 5.0 mL 0.00200 KSCN. She finds that the

    concentration of FeSCN2+ in the equilibrium mixture is 0.000125 M. Follow these steps to determine the corresponding experimental value of Kc for the reaction of Fe3+

  64. NaI(aq)+Hg2(C2H3O2)2(aq)-->

    Express your answer as a chemical equation. Enter NOREACTION if no reaction occurs. Identify all of the phases in your answer. I need help! Someone please help..

  65. 1) Which statement best defines metallurgy?

    a metal made by combining two or more metallic elements, designed to improve the quality of the compound the protection of the environment, workers, and local communities during the process of metal extraction and

  66. At 40 degrees Celsius, the value of Kw is 2.92 X 10^-14

    a.) calculate the [H+] and [OH-] in pure water at 40 degrees celsius b.)what is the pH in pure water at 40 degrees celsius c.)if [OH-] is .18M , what is the pH

  67. Calculate the oxidation number of sulphur in AL2(SO4)3

  68. A sample of argon gas at STP occupies 56.2 liters. Find the number of moles of argon and the mass in the sample

  69. If a mothball (C10H8) has a mass of 1.32 grams, how many naphthalene molecules does it contain?

    If I'm right just multiply 1.32g by 6.022*10^23 and the answer is 7.949*10^23 molecules. Is this right?

  70. Calculate the pH of a solution that was created by combining 250.0 mL of 0.25 M HCl with 100.0 mL of 0.11 M HI. Assume the volumes are additive.

  71. Calculate Delte G Knot for H20(g) + 1/2 O2 <-> H2O2(g) at 600. K, using the following data:

    H2(g) + O2(g) <-> H2O2 (g) K = 2.3 X 10^6 at 600. K 2H2(g) + O2(g) <-> 2H20(g) K= 1.8 X 10^37 at 600. K

  72. 5. A student has the following data: V1 = 822 mL, T1 = 75°C and T2 = -25°C. He calculates V2 and gets -274 mL is this value correct? Explain why or why not.

  73. NH3(aq)+H2O(l)⇄NH4+(aq)+OH−(aq)

    Kb=1.8×10−5 at 25C Initial [NH3] | Equilibrium [NH4+] | Equilibrium [OH−] | pOH 0.15 | 1.6×10−3 | 1.6×10−3 | 2.78 0.30 | 2.3×10−3 | ? | ? NH3 is a weak base that reacts with water according to the chemical

  74. Two cells are connected in series . One contains AlCl3, and the other contains AgNO3 as the electrolytes. What mass of Ag is deposited when 18g of Al is deposited at cathode?

  75. H2C2O4.2H2O(s) is primary standard substance. 2.3688g of oxalic acid hydrate were completely neutralized by 42.56ml of NaOH solution. Calculate the molar concentration of the NaOH solution. Write the balanced equation for the reaction.

  76. What volume of a 15.0% by mass NaOH solution, which has a density of 1.116 g/mL, should be used to make 4.40 L of an NaOH solution with a pH of 10.5?

  77. Balance the following equation for a half reaction that occurs in basic solution. Use e– as the symbol for an electron.

    SO3^2- ---> S2O4^2-

  78. How many oxygen atoms are represented in the formula Fe2(SO4)3?

  79. In a titration experiment, 20.4 mL of 0.883 M 𝐻𝐶𝑂𝑂𝐻 neutralize 19.3 mL of 𝐵𝑎(𝑂𝐻)2. What is the concentration of the 𝐵𝑎(𝑂𝐻)2 solution?

    Do I use M1V1=M2V2? my answer is 0.467, is this correct?

  80. Calcium hydroxide, Ca(OH)2, dissolves in water to the extent of 1.78 g per liter. What is the value of Ksp for Ca(OH)2?

  81. Write the dissociation equation for iron(II) ammonium sulfate hexahydrate in water .

    Fe(NH4)2(SO4)2 * 6H2O --> __?________ I know dissociate means to take apart so for example; NaCl would look like Na^+ + Cl^- And another one like: Fe2(SO4)3 would look like

  82. Calculate the solubility (in g/L) of calcium fluoride in water at 25°C if the Ksp for is 1.5 × 10-10 .

  83. The regression line from a plot of absorbance vs. concentration yields: 𝐴 = 2.31[𝐶] + 0.002. If the absorbance of an unknown is measured to be 0.124, what is the concentration of the analyte [𝐶]?

  84. iron metal & oxygen combine to form magnetic oxide of iron, Fe3O4. How many mols of iron can be converted to magnetic by 8.80 mols of pure oxygen?

  85. Which of the following pairs would make a good buffer?

    A. H2C2O4 and HC2O4- B. HNO3 and NO3- C. NaOH and NaCl D. HCl and NaOH Would it be C? I think I remember learning about these in a lesson about buffers, hence why my instinct is to go with C...

  86. A steel tank at 300 K contains 0.285 L of gas at 1.92 atm pressure. The tank is capable of withstanding a maximum pressure of 5.76 atm. Assuming that doubling the kelvin temperature causes the internal pressure to double,

    a. at what temperature will the

  87. Given the following reaction for photosynthesis, 6CO2 + 6H2O --> C6H12O6 + 6O2, how many liters of O2 can be produced from 100 g of water at standard temperature and pressure?

  88. Which of the following systems could act as a buffer?

    A. HCl/Cl- B. NaOH/OH- C. HSO4-/SO4-2 D. H3O+/OH- E. All of the above my guess is C because A and B are too strong, but I am unsure of D. Can someone explain how to think through this?

  89. How much reaction is complete when Kc=1,

    options: a.10% b.25% c.50% d.100% please explain the answer

  90. What is the only positive ion found in H2SO4(aq)?

    a. ammonium ion b. hydronium ion c. hydroxide ion d. sulfate ion The answer's b, but I don't understand why.

  91. Indicate how many stereoisomers are possible for each compound.

    b) tetrahedral [NiCl2Br2]2– c) octahedral [Fe(CO)4BrCl]

  92. HA and HB are two strong monobasic acids.

    25.0cm3 of 6.0moldm–3 HA is mixed with 45.0cm3 of 3.0moldm–3 HB. What is the H+(aq) concentration, in mol dm–3, in the resulting solution? A 1.9 B 2.1 C 4.1 D 4.5 could you please explain how you reach an

  93. A 500 mL metal cylinder holding 0.100 moles of helium gas is known to rupture at a pressure of 10 atmospheres. At what temperature, in °C, will the container fail?

    Here is what I came up with: T= (1.00mol x 0.0821 LxATM/KxMOL) / 10atm x 0.5L =0.01642K

  94. Determine the number of moles and the mass of argon occupying 37.8L at stp

  95. Calculate the mass of CaCl2 formed when 5 moles of chlorine reacts with chlorine metal?

  96. When 52.7 g of octane (c8 h18) burns in oxygen, the percentage yield of carbon dioxide is 82.5%. what is the actual yield in grams?

  97. Which of the following will be more soluble in an acidic solution than in pure water?

    Be(OH)2 Ag2SO4 RbClO4 CuCN Cul

  98. The concentration of a solution is 284,000 ppm. How many grams of solute is contained in 100 grams of solution?

  99. Calculate the percentage by mass of silicon tetrachloride.

  100. The Ksp for BaCrO4 is 1.2X10-10. Will BaCrO4 precipitate when 10 mL of 1 X10-5M Ba(NO3)2 is mixed with 10 mL of 1X10-3M K2CrO4?

    I am not sure where to start

  101. Which type of sulphide has a Zig-Zag chain structure?

  102. What is the colour of:

    1. Cu+ 2. Cu2+ 3. Cu3+?

  103. Ca(OH)2 has a Ksp of 6.5×10−6.

    If 0.370 g of Ca(OH)2 is added to 500 mL of water and the mixture is allowed to come to equilibrium, will the solution be saturated?

  104. CHECK MY ANSWERS PLEASE.

    1) Which activity would be considered resource extraction? eating beef eating deer hunting deer < MY ANSWER raising cattle ----- 2) How does clear-cutting a forest directly affect climate? Fewer trees lead to less stable soil in

  105. C7H6O3(s) + C4H6O3(l) → C9H8O4(s) + HC2H3O2(l)

    is the equation. At 20 degree celsius, how many liters of acetic acid, HC2H3O2, would be formed? The density of acetic acid is 1.05g/cm3.

  106. What volume of CO2 gas is produced when 20 gm of 20% pure CaCO3 is completely heated?

  107. Describe how you would prepare a pure dry sample of calcium chloride in the laboratory

  108. A 25.0 mL sample of 0.100 M propanoic acid (HC3H5O2, Ka = 1.3 ✕ 10-5) is titrated with 0.100 M KOH solution. Calculate the pH after the addition of the following amounts of KOH.

    a) 20.0 mL b) 25.0 mL c) 30.0 mL

  109. How many carbon tetrachloride (CCl4) molecules are in 3.00 mol of CCl4? How many carbon atoms? How many chlorine atoms? How many total atoms?

    I have no idea how to do all of this =\

  110. What is the mass of 3.01 x 10^22 iron (II) ions, Fe^2+?

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