chemistry

Most popular questions
  1. Chemistry

    Hi. Is PO4(3-) polar or non-polar? Why or why not? Thanks! Look up the electronegativity of P and O. I think I remember that O is about 3.5 and P is about 2.1; therefore, each P-O bond is somewhat polar. Thus, the ion will be polar unless the Lewis

    asked by Sally on November 23, 2006
  2. Chemistry

    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

    asked by tec on March 19, 2014
  3. Chemistry

    Identify the predominant intermolecular force in each of these substances. 1. Hydrogen 2. Dipole-Dipole 3. London A)H20 B)NH3 C)CH3 C=O OCH3 D)CH4 E)CH OH-C-OH CH3 what I have so far is A) 1 B) 1 C) 2 D) 3 E) I'm not sure about E, I think it might be

    asked by Dan on December 7, 2015
  4. Chemistry

    Consider the following reaction: 2Fe2O3 --> 4Fe + 3O2 ∆Hrxn° = +824.2 kJ The decomposition of 29.0 g of Fe2O3 results in a. the release of 150 kJ of heat b. the release of 12000 kJ of heat c. the absorption of 12000 kJ of heat d. the absorption of 150

    asked by Anonymous on September 21, 2013
  5. Chemistry

    Anthracene is a yellow, crystalline solid found in coal tar. Complete this structure for anthracene, C14H10, by adding bonds and hydrogen atoms as necessary. What type of hybrid orbitals are utilized by carbon in anthracene? >>sp3 How many σ bonds and π

    asked by Dan on November 22, 2015
  6. chemistry

    Is NH4+ a polar or nonpolar bond?

    asked by Lin on November 30, 2007
  7. chemistry

    Suppose you take a trip to a distant universe and find that the periodic table there is derived from an arrangement of quantum numbers different from the one on Earth. The rules in that universe are: 1. principal quantum number n = 1, 2, . . . (as on

    asked by Anonymous on April 2, 2013
  8. Chemistry

    how do i write the complete electron configuration for Ga3+ and Mg2+????????????

    asked by mariana on August 4, 2013
  9. Chemistry

    A gas is allowed to expand at constant temperature from a volume of 2.00 L to 11.20 L against an external pressure of 1.500 atm. If the gas loses 256 J of heat to the surroundings, what are the values of q, w, and ΔU? Pay careful attention to units.

    asked by Syed on October 9, 2012
  10. Chemistry

    The standard internal energy change for a reaction can be symbolized as ΔU°rxn or ΔE°rxn. For the following reaction equations, calculate the energy change of the reaction at 25 °C and 1.00 bar. Sn(s) + 2Cl2(g) --> SnCl4(l) ΔH°rxn = -511.3 kJ/mol

    asked by Anonymous on September 21, 2013
  11. chemistry

    Which of the following reactions have a positive ΔSrxn? Check all that apply. A(g) +B(g) -----> 3C(g) A(g)+ B(g)------> C(g) 2A (g) +2B (g)-----> 3C(g) A(s)+B(s)------> C(g) I picked the first one and it marked me wrong. Please help(:

    asked by Jerry on March 14, 2012
  12. chemistry

    What is the complete ionic equation for CaS(aq) +CuCl2(aq)=CuS(s)+CaCl2(aq)

    asked by lupe on April 8, 2010
  13. Chemistry

    Consider each of the following reactions and decide whether the standard entropy change for the reaction will be, (a) Positive; or (b) Very close to Zero; or (c) Negative. Matching pairs N2 (g) + 3 H2 (g) = 2 NH3 (g) Mg (s) + CO2 (g) = MgO (s) + CO (g)

    asked by Chem Lover on November 28, 2009
  14. Chemistry

    Which of the following electron configurations of neutral atoms represent excited states? ( ) [Xe]6s24f1 ( ) 2s2 ( ) 1s22s22p63s23p63d2 ( ) [Ar]4s23d3 ( ) [Kr]5s14d5

    asked by Garcia on November 11, 2012
  15. Chemistry

    How many grams of CO are needed to react with an excess of Fe2O3 to produce 209.7gFe? Fe2O3(s) + 3CO(g) => 3CO2(g) + 2Fe(s)

    asked by Shelly on May 17, 2012
  16. chemistry

    Ethanol (C2H5OH) melts at -114 °C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135 °C to liquid

    asked by Anonymous on February 3, 2012
  17. Chemistry

    At 298 K, the Henry\'s law constant for oxygen is 0.00130 M/atm. Air is 21.0% oxygen.At 298 K, what is the solubility of oxygen in water exposed to air at 1.00 atm? At 298 K, what is the solubility of oxygen in water exposed to air at 0.896 atm? If

    asked by Colleen on February 7, 2013
  18. Chemistry

    A colourless solution contains one type of ion. When one adds dilute HCl to it, a white precipitate initially forms. However, once more of the HCl solution is added, the precipitate dissolves. Explain why the ion is Pb2+ and not Al3+, Hg22+, Cu2+ nor Ag+.

    asked by Vic on September 3, 2007
  19. chemistry

    Which of the following diatomic species are paramagnetic and which are diamagnetic? A blank molecular orbital diagram (Part B 1 figure) has been provided to help you. Drag the formulas to the appropriate magnetic bin :C2^2+,Li2-,B2^2-

    asked by defferan on November 19, 2008
  20. Chemistry

    I just need someone to check over my answers, I'm pretty confident in all of them! In which six-membered hydrocarbon rings are all of the C-C-C angles roughly the same, i.e., within 1o? Select ALL that apply. Question 1 options: A)cyclohexane B)cyclohexene

    asked by Dan on December 9, 2015
  21. Chemistry

    Write a balanced net ionic equation (include physical states) for the following reaction: Fe(NO3)3(aq) + LiOH(aq) → LiNO3(aq) + Fe(OH)3(s)

    asked by Emily on June 27, 2011
  22. CHEMISTRY

    Consider the following balanced equation: 2N2H4(g)+N2O4(g)→3N2(g)+4H2O(g) Complete the following table showing the appropriate number of moles of reactants and products. If the number of moles of a reactant is provided, fill in the required amount of the

    asked by Run on October 5, 2014
  23. Chemistry

    FeSCN2+ -> Fe3+ + SCN- Solution is initially dark red. If some Ag+ is added to form AgSCN. what happens to position of equilibrium? what happens ot the color?

    asked by Grace on February 8, 2011
  24. Chemistry

    Consider the decomposition of a metal oxide to its elements, where M represents a generic metal. M203(s)---> 2M(s) + 3/2 O2(g) info given for Gf(kJ/mol): M203= -10.60 M(s)=0 O2(g)= 0 1.) what is the standard change in Gibbs energy for rxn as written in

    asked by Kelsey on March 15, 2012
  25. Chemistry

    Part A Calculate the standard enthalpy change for the reaction 2A+B --->2C +2D Use the following data: Substance Delta H(kJ/mol) A -263 B -391 C +203 D -523 Express your answer in kilojoules. MY ANSWER FOR PART A: Delta H =277 kJ PART B----THIS ONE I NEED

    asked by tina on June 16, 2011
  26. Chemistry

    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..

    asked by Lalo on October 27, 2012
  27. Chemistry

    For the following: i) HClO4 > HBrO4 > HIO4 ii) NH3 > PH3 > AsH3 > SbH3 iii) HOClO3 > HOClO2 > HOClO > HOCl iv) HBr>HCl>HF The order of acidity is correct for which series? 1. ) all are correct 2. ) ii and iii 3. ) ii and iv 4. ) ii 5. ) i, iii, iv

    asked by Apple on November 22, 2009
  28. Chemistry

    The normal boiling point of ethanol is 78.4°C. When 9.16 g of a soluble nonelectrolyte was dissolved in 100. g of ethanol, the vapor pressure of the solution at that temperature was 7.40 102 Torr. (a) What are the mole fractions of ethanol and solute? (b)

    asked by Daiyo on December 10, 2010
  29. Chemistry

    For Mn3+, write an equation that shows how the cation acts as an acid.

    asked by Ari on February 12, 2011
  30. chemistry

    Complete and balance the molecular equation, including phases, for the reaction of aqueous ammonium bromide, NH4Br, and aqueous lead(II) acetate, Pb(C2H3O2). Enter the balanced net ionic equation, including phases, for this reaction.

    asked by Kelly on October 23, 2012
  31. Chemistry

    Carbonic acid forms when carbon dioxide dissolves in water according to this equation: CO2+H2O =H2CO3 How many moles of CO2 must dissolve in an excess of water to produce 3 moles of H2CO3?

    asked by Jake on December 17, 2018
  32. Chemistry

    The density of pure silver is 10.5 g/cm3 at 20 °C. If 5.25 g of pure silver pellets is added to a graduated cylinder containing 11.2 mL of water, to what volume level will the water in the cylinder rise?

    asked by Crissy on September 5, 2012
  33. Chemistry

    Ethanol (C2H5OH) melts at -114 degrees Celsius. The enthalpy of fusion is 5.02 kj/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135 degrees Celsius to

    asked by Kylie on May 4, 2014
  34. Chemistry

    A mixture of C3H8 and C2H2 has a mass of 2.3g . It is burned in excess O2 to form a mixture of water and carbon dioxide that contains 1.6 times as many moles of CO2 as of water. What is the mass of C2H2 in the original mixture?

    asked by Matt on October 19, 2013
  35. Chemistry

    How much work must be done on a system to decrease its volume from 14.0 L to 5.0 L by exerting a constant pressure of 4.0 atm?

    asked by Anonymous on October 22, 2014
  36. Chemistry

    Many power plants produce energy by burning carbon-based fuels, which also produces CO2. CO2 is a greenhouse gas, so over-production can have negative effects on the environment. Use enthalpy of formation data to calculate the number of moles of CO2 (g)

    asked by Harold on January 27, 2011
  37. chemistry

    Consider the reaction, C2H4 (g) + H2 (g)- C2H6 (g) where -137kJ of heat is released. How many kilojoules are released when 55.3g of C2H4 reacts?

    asked by Sandy on July 10, 2011
  38. chemistry

    Write a balanced equation, ionic equation and the net ionic equation for the following: A) Li2SO4 + Sr(NO3)3 ---> B) H2SO4 + Na2CO3 --->

    asked by Mindu on January 12, 2015
  39. chemistry

    the reaction of 7.10g carbon with excess O2 yields 12.25g of CO2. what is the percent yield of this reaction? I have tried everything and looked through all of my notes and nothing is working for stiochiometry

    asked by Heather on October 6, 2014
  40. Chemistry

    2H2+O2 -> 2H20 changeHrxn=-484 KJ Which answer best describes the transfer heat that occurs when 1.30 mol of H2 reacts? 629 KJ released 315 KJ absorbed 315 KJ released 484 KJ absorbed 484 KJ released 629 KJ absorbed

    asked by Anonymous on October 9, 2012
  41. Chemistry

    at 25C and 795 torr, carbon dioxide has a solubility of 0.0356 M in water. What is the solubility at 25 C and 2070 torr? ____ M I know that at a given temperature, the solubility of a gas in a liquid is directly proportional to its pressure but how would

    asked by David on February 16, 2012
  42. Chemistry

    How would the dx2−y2 orbital in the n=5 shell compare to the dx2−y2 orbital in the n=3 subshell? True or False 1.The contour of the orbital would extend further out along the x and y axes. 2. The value of ℓ would increase by 2. 3.The radial

    asked by Kristine on April 24, 2014
  43. Chemistry

    A solution of household bleach contains 5.25% sodium hypochlorite, NaOCl, by mass. Assuming that the density of bleach is the same as water, calculate the volume of household bleach that should be diluted with water to make 500.0 mL of a pH = 10.10

    asked by JayJay on May 29, 2013
  44. Chemistry

    A 0.110-L sample of an unknown HNO3 solution required 52.1 mL of 0.150 M Ba(OH)2 for complete neutralization. What was the concentration of the HNO3 solution?

    asked by Lori on November 9, 2013
  45. chemistry

    A 100 w lightbulb is place in a cylinder equipped with a moveable piston. The ligshtbulb is turned on for 0.015 hours, and the assembly expands from initial volume of 0.85 L to a final volume of 5.88 L against an external pressure of 1.0 atm. Use the

    asked by Ebimobowei on April 4, 2015
  46. Chemistry

    Balance the following redox equations. All occur in Acidic solutions. 1. Cr2O7^2-^ + C2O4^2-^ -> Cr^3+^ + CO2 2. Cu + NO3^-^ -> CU^2+^ + NO 3. MnO2+ HNO2 -> Mn^2+^ + NO3^-^ 4. PbO2 + Mn^2+^ + SO4^2-^ -> PbSO4 + MnO4^-^ 5. HNO2 + Cr2O7^2-^ -> Cr^3+^ +

    asked by Yukiko on September 3, 2008
  47. Chemistry

    For another picnic, you want to make hamburgers with pickles, again without having any left over. You need to balance the number of packages of buns (which usually contain 8 buns) with the number of packages of hamburger patties (which usually contain 12

    asked by Becca on January 19, 2015
  48. Chemistry

    Predict how the entropy of the substance is affected in the following processes: a) O2 (g,200 kPa, 300k) --> O2 (g, 100, 300k) b)Br2 (l, 1 bar, 25 degree C) --> Br2 (g, 1 bar, 25 degree C) C)Fe (s, 1 bar, 250 degree C)--> Fe(s, 1 bar, 25 degree C) will

    asked by Alexis on April 20, 2014
  49. Chemistry

    Identify any incorrect formulas. explain your answer. a. Mg2(SO4)3 b. Rb3As c. BeCl3 d. NaF

    asked by Minny on November 5, 2009
  50. chemistry

    for a homework problem it says to build both the high spin and low spin complex ion and it gives me spin of Fe (ox)3 3- low high I don't understand what high spin and low spin is and I don't know what Fe (ox)3 3- is suppose to be

    asked by Judy on June 30, 2010
  51. Chemistry

    Imagine that you have a 7.00L gas tank and a 3.50L gas tank. You need to fill one tank with oxygen and the other with acetylene to use in conjunction with your welding torch. If you fill the larger tank with oxygen to a pressure of 135atm , to what

    asked by De'Brickashaw on August 20, 2014
  52. chemistry

    disappearance of NO in ...- Help!!!? The following data were collected for the rate of disappearance of NO in the reaction 2 NO(g) + O2(g) ¨ 2 NO2(g). Run: [NO](M) [O2](M) Initail Rate (M/s) 1 .0126 .0125 1.41 X 10^-2 2 .0252 .0125 5.64 X 10^-2 3 .0252

    asked by Hannah on January 30, 2013
  53. Chemistry

    When the oxide of generic metal M is heated at 25.0 °C, only a negligible amount of M is produced. O2M(s) ----> M(s) +O2(g) delta G= 288.9 Kj/mol When this reaction is coupled to the conversion of graphite to carbon dioxide, it becomes spontaneous. What

    asked by Jerry on March 14, 2012
  54. Chemistry

    CCl3F boils at 23.8 degrees Celcius, and its molar heat of vaporization is 24.8 kJ/mol. Calculate the molar entropy of vaporization of CCl3F (l)

    asked by Kay on January 31, 2012
  55. CHEMISTRY

    At 25°C and 730 mm pressure,380 ml of dry oxygen was collected.If the temperature is constant ,what volume will the oxygen occupy at 760 mm pressure ? ANSWER- 365ml

    asked by Tanya on March 22, 2015
  56. chemistry

    A 15.27 g sample of Mo2O3(s) is converted completely to another molybdenum oxide by adding oxygen. The new oxide has a mass of 18.33 g. Add subscripts below to correctly identify the empirical formula of the new oxide.

    asked by anon on September 18, 2014
  57. Chemistry

    Write a chemical equation representing the second ionization energy for lithium. use e- as the symbol for an electron.

    asked by anonymous on April 1, 2013
  58. Chemistry

    1) What Physical properties, other than specific heat, could you use to help identify unknown metals? 2) Why is water an excellent material to use in a calorimeter? Density, color, resistivity (or conductitivy), melting point, crystallization. 2) water is

    asked by K. on September 21, 2006
  59. chemistry

    prepare M/20 solution of oxalic acid. Find out the molarity and strength in gram per litre of the given solution of potassium permanganate with the help of the prepared solution of oxalic acid

    asked by sidd on April 5, 2011
  60. Chemistry

    A 30.0 mL sample of 0.165 molL−1 propanoic acid (Ka=1.3×10−5) is titrated with 0.300 molL−1KOH. Calculate the pH at 0, 5,10, at equivalence point, 1/2 of the equivalence point, 20, 25 mL of added base.

    asked by Sam Dowen on November 22, 2016
  61. Chemistry

    What would the net ionic equation be for : HBr (aq) + KOH (aq) = KBr + H2O

    asked by Emma on October 15, 2017
  62. Chemistry

    Using the following data calculate Delta Sfus and Delta Svap for K in J/mol-k Tm(K) = 336, Delta H Fus(kJ/mol) = 2.33, Tb (K) = 1033, Delta H vap (kJ/mol) = 77.1 For Delta S fus i'm supposed to use 336 K the Tm value and for Delta S vap i'm supposed to use

    asked by Katherine on March 9, 2012
  63. Chemistry

    Calculate the maximum wavelength of light capable of removing an electron for a hydrogen atom from the energy state of n=4 if it requires an energy of at least 1.36 x10^-19 J to do this. I just want to know how to find the second n value so i can solve

    asked by Maxx on February 22, 2016
  64. chemistry

    Given that S is the central atom, draw a Lewis structure of OSF4 in which the formal charges of all atoms are zero

    asked by defferan on November 15, 2008
  65. chemistry

    10.0 mL of a Cu2+ solution of unknown concentration was placed in a 250 mL Erlenmeyer flask. An excess of KI solution was added. Indicator was added and the solution was diluted with H2O to a total volume of 75 mL. The solution was titrated with 0.20 M

    asked by Samantha on November 19, 2014
  66. Chemistry

    For the following chemical reaction... HCN (aq) + KOH (aq)----> H2O (l) + KCN (aq) write the net ionic equation, including the phases

    asked by Chelsea on October 4, 2013
  67. chemistry

    An unknown metal is found to have a density of 19.300 g/cm^3 and to crystallize in a body-centered cubic lattice. The edge of the unit cell is found to be 0.31627 nm. Calculate the atomic mass of the metal. Im not sure how to approach this problem...when i

    asked by sam on January 24, 2011
  68. Chemistry

    Express the concentration of a 0.0510 M aqueous solution of fluoride, F-, in mass percentage and in parts per million. Assume the desnity of the solution is 1.00 g/mL Since, we're assuming the density I think that also means were assuming the volume.. but

    asked by Joy on February 19, 2012
  69. chemistry

    For each trial, enter the amount of heat gained by the chemical system of ammonium nitrate, qrxn. The specific heat of water is 4.184 J/goC. Report your answer using 4 digits. The information given is: Trial # Tiwater Tf Masswater #1: 21.2 10.8 24.990 #2:

    asked by Megan on April 6, 2010
  70. chemistry

    For the following: i) H3PO4 > H3AsO4 > H3SbO4 ii) H2Te > H2Se > H2S > H2O iii) HCl > HBr > HI iv) SbH3 > AsH3 > PH3 > NH3 The order of acidity is correct for which series? 1. ) all are correct 2. ) i and ii 3. )i, ii and iv 4. ) ii, iii 5. ii, iv I know

    asked by bob on November 24, 2009
  71. Chemistry

    In a thermochemistry experiment the reaction of 0.0857 g of an unknown metal and an excess of 4.0 M HCl resulted in a 0.210 mL decrease in the volume of an ice/water mixture. Calculate the enthalpy of this reaction per 1 g of metal reacted. Needed data:

    asked by Raj on December 1, 2007
  72. Chemistry

    How much heat is absorbed/released when 35.00 g of NH3(g) reacts in the presence of excess O2(g) to produce NO(g) and H2O(l) according to the following chemical equation? 4NH3(g)+5O2(g)--->4NO(g)+6H2O(l) DeltaH=1168kj

    asked by Daqa on March 18, 2010
  73. Chemistry

    Label each of the following reactions as exothermic or endothermic ("exo" or "endo"), and according to whether work is done on or by the system, or no work is done at all ("on", "by" or "none")? Note that no "endo-on" cases appear here, as these are always

    asked by victor on November 22, 2009
  74. Chemistry

    Explain the difference in acidity of MgO dissolved in water and of P4O10 in water in terms of position of the element in the periodic table and bonding. I found MgO is basic and P4O10 is acidic

    asked by Po on November 16, 2016
  75. chemistry

    select from the following the most appropriate concentration for NaOH to titrate a sample that contains 250mg of aspirin: a. 0.01 M b. 0.10 M or c. 1.0 M and explain why you chose it.

    asked by Anonymous on November 13, 2012
  76. chemistry

    1. For which of these elements would the first ionization energy of the atom be higher than that of the diatomic molecule? a. boron b. helium c. oxygen d. lithium

    asked by Anonymous on November 4, 2013
  77. Chemistry

    Ba(OH)2 is a strong electrolyte. Determine the concentration of each of the individual ions in a 0.700 M Ba(OH)2 solution. I know that Ba(OH)2 -> Ba + 2OH But how do I determine the concentrations? I feel like I am making this more complicated than need be

    asked by Hana on April 8, 2013
  78. Chemistry

    When 20.5g of methane and 45.0g of chlorine gas undergo a reaction that has a 75.0% yeild, what mass of chloromethane forms?

    asked by Sam on September 29, 2009
  79. chemistry

    100 mL of is initially at room temperature (22)C. A chilled steel rod at 2 C is placed in the water. If the final temperature of the system is 21.2 C, what is the mass of the steel bar? Specific heat of water = 4.18J/g(C) Specific heat of steel =

    asked by Lilit on October 20, 2008
  80. chemistry

    When combined with cupric ions (aq, 1M) which will produce the largest standard cell voltage? a. ) KMnO4(aq) b. ) MnO2(s) c. ) MnCl2(aq) d. ) Mn(s)

    asked by Anonymous on November 23, 2008
  81. chemistry

    the vapor pressure of water at 45.0 °c is 71.93 mmhg. Calculate the vapor pressure of a solution of 1.50 m Al(NO3)3 at this temperature (assume 100% dissociation)

    asked by michael on July 16, 2013
  82. CHEMISTRY

    Assuming equal concentrations, rank these aqueous solutions by their freezing point: LiSO4, Li3PO4, SnCl4, NH4Br. (from highest freezing point to lowest freezing poinT) Thanks.

    asked by Kylie on February 18, 2012
  83. Chemistry

    It turns out that the Van Dar Waals constant b is equal to four times the total volume actually occupied by the molecules of a mole of gas. Using this figure, calculate the fraction of the volume in a container actually occupied by Ar atoms: a) at STP b)

    asked by Anonymous on January 9, 2011
  84. Chemistry

    Explain how the calculated molarity of the potassium permanganate would be affected by each of the following experimental errors. In each case, you must also state if the calculated molarity is higher or lower than the actual morality. a) Some sodium

    asked by 4B on December 1, 2011
  85. chemistry

    According to the following thermochemical equation, what mass of H2O (in g) must form in order to produce 975 kJ of energy? SiO2(s) + 4 HF(g) → SiF4(g) + 2 H2O(l), ΔH°rxn = -184 kJ

    asked by Amber on June 14, 2011
  86. chemistry

    Gallium is a metal with a wide variety of uses. Some of its applications include computer memory chips, light emitting diodes and lasers. Radioactive isotopes of gallium are used to image the human body and locate tumors. Naturally occurring gallium

    asked by billy on August 29, 2014
  87. Chemistry

    A protein subunit from an enzyme is part of a research study and needs to be characterized. A total of 0.135g of this subunit was dissolved in enough water to produce 2.00 mL of solution. At 28 ∘C the osmotic pressure produced by the solution was 0.138

    asked by Al on June 27, 2014
  88. Chemistry

    Rank Cd, Br, and Si from worst to best conductor of electricity. Is it Br, Cd, Si? Thanks -MC

    asked by mysterychicken on February 7, 2014
  89. chemistry

    Compare a mole of Ag-108 and a mole of Pt-195 using atoms, protons, electrons, and neutrons.

    asked by Astrid on March 11, 2010
  90. chemistry

    Q.1 Calculate the extent of hydrolysis of 0.005M K2CrO4.If K2=5*10^-7 for H2CrO4.(It is essentially strong for first ionisation).

    asked by mohit on January 8, 2010
  91. Chemistry

    If you have 320.0 mL of water at 25.00 °C and add 110.0 mL of water at 95.00 °C, what is the final temperature of the mixture? Use 1.00 g/mL as the density of water.

    asked by Ryan on October 18, 2011
  92. chemistry

    how do you know which halide salts confirms a presence of F- ions, Cl- ions, Br- ions, and I- ions?

    asked by Amanda on February 4, 2008
  93. chemistry

    what volume (in ML) of a 0.150 M HNO3 solution is required to completely react wtih 35.7 mL of a 0.108 M Na2CO3 solution according to the following balanced chemical equation? Na2CO3(aq) + 2 HNO3(aq) --> 2NaNO3(aq) + H2O(l) then, in the reaction above,

    asked by samantha on June 21, 2010
  94. Chemistry

    A 35.1g sample of solid CO2 (dry ice) is added to a container at a temperature of 100k with a volume of 4.0L. If the container is evacuated (all of the gas removed), sealed and then allowed to warm to room temperature (T=298K) so that all of the solid CO2

    asked by Ricky on January 20, 2018
  95. Chemistry

    Consider an alloy that is 14.1% copper by mass in tin. Copper makes up what percentage of the atoms in this sample?

    asked by Seth on February 12, 2017
  96. chemistry

    How many calories are required to heat 25.0 g of platinum from 24.5 °C to 75°C (specific heat of platinum = 0.139 J/gK)? 1. 47 cal 2. 42 cal 3. 48 cal 4. 20 cal 5. 80 cal Thank you.

    asked by Danny on November 22, 2009
  97. chemistry

    Calculate the delta H for the reaction N2H4(l)+ O2(g) --> N2(g) + 2H20(l) Given the following data: 2NH3(g) + 3N20(g) --> 4N2(g) + 3H20(l) N20(g) + 3H2(g) --> N2H4(l) + H20(l) 2NH3(g) + 1/2O2(g) --> N2H4(l) + H20(l) H2(g) + 1/2O2(g) --> H20(l)

    asked by kilo on October 28, 2009
  98. CHEMISTRY

    Calculate the change in entropy that occurs when 17.68 g of ice at -12.7°C is placed in 54.05 g of water at 100.0°C in a perfectly insulated vessel. Assume that the molar heat capacities for H2O(s) and H2O(l) are 37.5 J K-1 mol-1 and 75.3 J K-1 mol-1,

    asked by Sarah on October 23, 2012
  99. chemistry

    The standard internal energy change for a reaction can be symbolized as ΔU°rxn or ΔE°rxn. For the following reaction equations, calculate the energy change of the reaction at 25 °C and 1.00 bar. Sn(s) + 2Cl2(g) --> SnCl4(l) ΔH°rxn = -511.3 kJ/mol

    asked by jake on February 28, 2016
  100. CHEMISTRY

    HOW CAN U TELL IF HNO3 +KNO3 IS A BUFFER SOLUTION A buffer solution must contain a weak acid and its conjugate base OR a weak base and its conjugate acid. HNO3 is a strong base and KNO3 is the salt of a strong base (KOH) and a strong acid (HNO3);

    asked by CANDY on February 27, 2007