Popular questions and responses by Natash
  1. chem

    choose the compound below that contains at least one polar covalent bond, but is nonpolar a. ICl3 b SeBr4 c. CF4 d. HCN Im stuck between C and D C is a tetrahedral which has no net dipole so is non polar, and D is linear which also makes it non polar.

    asked on May 1, 2008
  2. chem

    For the reaction shown, find the limiting reactant for each of the following initial amounts of reactants. 4Al(s)+3O2 (g)-->2Al2O3 (s) 4 mol Al 2.6 mol O2

    asked on October 1, 2008
  3. chem

    draw the lewis structure for NO2- including any valid resonance structures. which of the following statements are true? a. the nitrite ion contains 2 N-O bonds that are equivalent to 1 1/2 bonds. b. the nitrite ion contains 2 N=O double bonds c. the

    asked on May 1, 2008
  4. chemistry

    determine the vapor pressure of a solution at 55 degrees C that contains 34.2g NaCl in 375 mL of water. The vapor pressure of pure water at 55 degrees C is 118.1 torr. so Psolution=XsolventPsolvent I don't know why I'm not getting the correct answer... so

    asked on May 11, 2008
  5. chem

    A 4.55L sample of water contains .115g of sodium ions. Determine the concentration of sodium ions in ppm if the density of the solutions is 1.00g/mL. Ok so ppm=mass of solute/mass of solution *10^-6 so we have the mass of the solute .115g and for the

    asked on May 9, 2008
  6. chemistry

    which molecule or compound below contains a polar covalent bond? why? C2H4 LiI NCL3 ZnS AgCl

    asked on May 1, 2008
  7. chem

    Calculate the mole fraction of total ions in an aqueous solution prepared by dissolving .400 moles of MgCl2 in 850.0g of water. mole fraction =amount solute(in mols) /total amount of solute and solvent (in mols) so wouldn't it be .400/ .400+ 47.2 which is

    asked on May 11, 2008
  8. chem

    which of the following substances should have the highest melting point? Xe F2 SrS MgO CO2 the answers D, is it because its an ionic compound?

    asked on May 11, 2008
  9. chem

    Okay so Im doing a lab on preparation of K3[Fe(C2O4)3]*3H2O The final weight I got 2.835g. How can I find the theoretical yield of this? What do I need?

    asked on February 13, 2009
  10. chem

    in the ground state electron configuration of Fe3+, how many unpaired electrons are present? I thought it was 1, but im getting a wrong answer.

    asked on November 1, 2008
  11. chem

    How many mL of stomach acid (assume it is .035 M HCI) can be neutralized by an antacid tablet containing .231g Mg(OH)2?

    asked on April 21, 2008
  12. chemmm helppppppppp

    Consider the following reaction: 2N2O(g)--->2N2(g) + O2(g) a. express the rate of the reaction with respect to each of the reactants and products. b.In the first 10.0 s of the reaction, .018 mol of O2 is produced in a reaction vessel with a volume of

    asked on February 1, 2009
  13. acid-base titrations

    For each of the following circumstances, indicate whether the calculated molarity of NaOH would be lower, higher or unaffected. Explain your answer in each case. a.the inside of the pipet used to transfer the standard HCI solution was wet with water. b.You

    asked on April 21, 2008
  14. chem-acid-base titrations

    Acetic acid (HC2H3O2) is an important component of vinegar. A 10.00mL sample of vinegar is titrated with .5052 M NaOH, and 16.88 mL are required to neutralize the acetic acid that is present. a.write a balanced equation for this neutralization reaction

    asked on April 21, 2008
  15. chemistry

    use the data given below to construct a Born-Haber cycle to determine the lattice energy of CaO Ca(s)--->Ca(g) 193 Ca(g)--->Ca+(g) + e- 590 Ca+(g)--->Ca2+(g) +e- 1010 2O(g)---->02(g) -498 O(g) +e--->0-(g) -141 O-(g) + e---->O2-(g) 878 Ca(s) +1/2 O2(g)--->

    asked on May 1, 2008
  16. chem

    write the net ionic equation for the unknown titration reaction in this experiment. KHC8H4O4(aq) + NaOH(aq)----> KNaC8H4O4 + H2O(l)

    asked on April 7, 2008
  17. chem

    A 25.0 g aluminum block is warmed to 65.2 C and plunged into an insulated beaker containing 55.3g of water initially at 22.0C. the aluminum and water are allowed to come to thermal equilibrium. Assuming that no heat is lost, what is the final temperature

    asked on October 17, 2008
  18. chem

    HOw much energy is required to heat 36.0g H2O from a liquid at 65C to a gas at 115C? The following physical data may be uselful. Hvap=40.7kJ/mol C liquid=4.18 C gas=2.01 C solid= 2.09 T melting=0 C T boiling=100 C The answers about 87.7 kJ However I'm not

    asked on May 11, 2008
  19. Chemistry

    Why are titanium and gallium not very similar while lithium and sodium would be most similar ?

    asked on September 10, 2008
  20. chem

    what is the orbital diagram for Au+, how do you fit the f orbitals in?

    asked on November 23, 2008
  21. chem

    1. under what circumstances is the molecular geometry around a single central atom the same as the electron group geometry around the central atom? 2.If all of the electron groups around a single central atom are bonding, and the same outer atom is bonded

    asked on April 28, 2008
  22. chemical kinetics

    2H2O2 --->2H2O + O2 What is the instantaneous rate of formation of O2 at 50s? THeres a graph with the concentration of H2O2 as a function of time. at 50s the conc. is .2 But isnt this the concentration of H2O2, I don't understand. Also what is the

    asked on February 4, 2009
  23. chem lab

    set C: AgNO3(aq), Ba(NO3)2 (aq), HCI(aq), H2SO4(aq), NaOH(aq) what preliminary test results are you looking for to identify conclusively your unknown solutions as set C? Explain.

    asked on March 25, 2008
  24. chem

    In the trigonal bipyramidal geometry, which position- axial or equatorial- do nonbonding electrons prefer? why? I know its equatorial but I'm not exactly sure why

    asked on April 27, 2008
  25. chem

    How many oxygen atoms are in 1.90g og quartz (SiO2)? ok so 1.90g SiO2(1mol/60.0843g SiO2)(2 O mols/1 mol SiO2) (6.022*10^23atoms/1mol) what am i doing wrongg???

    asked on September 20, 2008
  26. acid-base titrations

    what is it important to keep the NaOH solution covered at all times? How will the molarity of the NaOH solution be affected by its continued exposure to the atmosphere? The pale pink color of the titration solution at the end point will fade to colorless

    asked on April 21, 2008
  27. chem

    Briefly explain why the transitions associated with the Lyman series correspond to wavelengths in the ultraviolet region of the electromagnetic spectrum.

    asked on April 14, 2008
  28. chem

    consider the following thermochemical equation for the combustion of acetone C3H6O(l)+4O2(g)---->3CO2(g)+3H2O(g) delta H rxn=-1790kJ. If a bottle of nail polish remover contains 179mL of acetone, how much heat would be released by its complete combustion?

    asked on October 17, 2008
  29. chem

    How many isomers of C2H3Br3 are possible? explain.

    asked on May 5, 2008
  30. thermodynamics

    A reaction has deltaHrxn=-127 kJ and delta S rxn=314 J/K. At what temperature is the change in entropy for the reaction equal to the change in entropy for the surroundings? so I made delta H-T delta S=0 plugged in values for S and H and solved for T. I got

    asked on February 18, 2009
  31. chem

    Find the percent by mass of sodium chloride in a 1.15M NaCl solution. The density of the solution is 1.07g/mL.

    asked on October 1, 2008
  32. chem

    How many CO2 molecules would be formed from the reaction mixture that produces the greatest amount of products? 2CH3OH(g)+3O2(g)--->2CO2(g)+4H2O(g)

    asked on October 1, 2008
  33. chem

    How much energy is required to ionize a hydrogen atom in its ground (or lowest energy) state? What wavelength of light contains enough energy in a single photon to ionize a hydrogen atom?

    asked on October 27, 2008
  34. chem-calorimetry

    If a 5.26-g sample of copper at 258C is placed in 125mL of water at 21.0C, how hot will the water get? Assume no heat loss to the surroundings. The specific heat of copper is .385 J/g C

    asked on March 31, 2008
  35. chem

    If 17.0g of MgSO4*7H2O is thoroughly heated,what mass of anhydrous magnesium sulfate will remain ? I don't even know where to begin on this one

    asked on September 20, 2008
  36. chromatography

    so we did this lab on chromatography, and in the beaker was 10 mL of HCI and 35 mL of acetone. IF the distilled water used to prepare the HCI solution in this experiment passed through iron pipes, then the HCI will be contaminated with FeCl3. Examine your

    asked on April 26, 2009
  37. chem

    How many CO2 molecules would be formed from the reaction mixture that produces the greatest amount of products? 2CH3OH(g)+3O2(g)--->2CO2(g)+4H2O(g)

    asked on October 1, 2008
  38. trig

    Give exact answers Sin(11pi/8) so this is sin(pi/4+pi/3) sin(pi/4)*cos(pi/3)+cos(pi/3)*sin(pi/4) rad2/2*1/2+1/2*rad2/2 which gives me rad2+rad2 all over 4 ...i don't know y im getting it wrong

    asked on November 15, 2008
  39. pre lab Q on chromatography

    suppose that there are two components, A and B, in a mixture. The chemical affinity of A for the stationary pahse is less than that of B and the chemical affinity of A for the mobile phase is greater than that of B. If the mixture is subjected to paper

    asked on April 19, 2009
  40. chemistry

    Rank the size of a change in temperature of one degree fahrenheit, one degree celsius, and one kelvin. Ok I can't seem to get this question right no matter what I do. Isn't one fahrenheit degree the largest then celsius and kelvin? There are 180 fahrenheit

    asked on August 30, 2008
  41. chemistry

    what are the 3 isomers of C2H2Cl2 what are 2 isomers of C2H3Br3, are any other isomers possible? explain.

    asked on May 5, 2008
  42. physics

    A 0.132kg baseball is dropped from rest. If the magnitude of the baseball's momentum is 0.811kg m/s just before it lands on the ground, from what height was it dropped? Calculate velocity from momentum. Then, knowing velocity at impact calculate height

    asked on April 17, 2007
  43. chem

    a soln. that is .195 M in CH3NH2 and .105 M in CH3NH3Br what is the balanced equation for this ? How do you know ?

    asked on March 8, 2009
  44. physics

    a point charge q=5.0 micro coulombs is placed at each corner of an equilateral triangle with sides .26 m in length. a. what is the magnitude of the electric field at the midpoint of any of the three sides of the triangle?

    asked on September 10, 2007
  45. chem

    Rank the following compounds in order of decreasing boiling point: KCI CO2 CH2O

    asked on December 7, 2008
  46. CHem

    Sterling silver is a mixture of silver and copper having a mole ration of silver to copper equal to 7.8 what is the mass percent composition of this mixture? Ok I know the answer to this and I know how its done: 1 mol Cu weighs 63.5 g 7.8 mol Ag weigh

    asked on September 23, 2008
  47. chem

    what kind of e-pair geometry, molecular geometry, and bond angles does C4H10 exhibit? I'm confused.

    asked on May 5, 2008
  48. physiology

    anaerobic respiration is triggered when the ratio of ________falls below a critical level. a.carbon dioxide supply to oxygen need b.oxygen supply to glucose need c.glucose supply to glucose need d.oxygen supply to oxygen need the electron transport chain

    asked on September 17, 2008
  49. chem-calorimetry

    what approach do you suggest using to prevent your water sample from cooling off beore you start your measurements?

    asked on March 31, 2008
  50. physics

    I neeeeeeeeeed helppp pronto, Measurements show that a honeybee in active flight can acquire an electrostatic charge as great as 93.0 pC a. how many electrons must be transferred to produce this charge? b.suppose 2 bees, each with a charge of 93.0pC, are

    asked on September 10, 2007
  51. physics pre-lab

    By trial and error with your calculator, find the angle theta for which sin theta and theta differ by 5%. This calculation must be done in radians. When you have found theta, express it in degrees. plzzz help thanx

    asked on March 22, 2009
  52. chem lab

    when an aqueous solution suspected of containing BA2+ or Pb2+ or both is mixed with sulfuric acid a precipitate forms. In another test, when the original solution is mixed with an aqueous solution of sodium sulfide no precipitate forms. What do these two

    asked on March 25, 2008
  53. organic chem/ melting pt lab

    why does a soluble impurity reduce the melting point range of a pure compound ? why is it advisable to run a mixed melting point determination on samples of two different compositions before concluding that the two compounds are identical ?

    asked on May 27, 2009
  54. chem

    The American Dental Association recommends that an adult female should consume 3.0mg of flouride per day to prevent tooth decay. If the flouride is consumed as sodium flouride (45.24% F)what amount of sodium flouride contains the recommended amount of

    asked on September 20, 2008
  55. chem lab

    when setting up their experiment, a student discovered that the solution in their flask turned bright pink upon adding 2 drops of the indicator, even before beginning the titration. what do you suspect was the mistake that the student made?

    asked on April 7, 2008
  56. chem

    The minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164kJ/mol. Calculate the longest wavelenght visible to the human eye

    asked on October 27, 2008
  57. chem

    In the reaction of calcium metal and water, 50.0 mL of hydrogen gas is collected over water at 25.0 degrees C with a total pressure of 752 mmHg. Calcualte the number of moles of hydrogen gas that was produced. Do we just plug this into n=pv/rt ? or is

    asked on May 11, 2008
  58. chem

    Is dimethyl ether a polar molecule? between dimethyl ether and ethyl alcohol, which molecule is expected to be more soluble in water? explain.

    asked on May 5, 2008
  59. statistics/probability

    One statistic used to assess professional golfers is driving accuracy, the percent of drives that land in the fairway. Driving accuracy for PGA Tour professionals ranges from about 40% to about 75%. Tiger Woods hits the fairway about 60% of the time. One

    asked on June 17, 2010
  60. chem

    what is the appropriate hybridization for the carbon atom in CO2? the explanation I was given is 2 electron groups around the center atom carbon suggest sp hybridization. the 2 unhibridized p orbitals on carbon form the 2 pi bonds. My question is why pi

    asked on November 24, 2008
  61. chem

    what is the electron configuration for Au+ ? where does f block fit in?

    asked on November 1, 2008
  62. chemistry

    write a balanced equation for the reaction that occurs when an aquesous solution of iron(II) chloride is mixed with an aqueous solution of potassium hydroxide

    asked on March 24, 2008
  63. chem/solubility

    the Ksp of CaF2 = 1.46*10^-10 and Ka of HF = 3.5*10^-4 Calculate the pH of a solution in which the solubility of CaF2 = .0100 moles/liter. so Ksp =[Ca2+][F-]^2 and Ka =[H3O+][F-]/[HF] I'm not sure how to continue...

    asked on May 13, 2009
  64. physics

    why is the total distance traveled by a mass traveling in a circle of radius R during n revolutions =2piRn. The average speed is the distance traveled divided by the elapsed time, so: v=2piRn/delta T, where delta T is the elapsed time.

    asked on March 8, 2009
  65. physics

    A 92kg astronaut and a 1.2E3kg satellite are at rest relative to the space shuttle. The astronaut pushes on the satellite, giving a speed of 0.14m/s directly away from the shuttle. Seven and a half seconds later the astronaut comes into contact with the

    asked on April 17, 2007
  66. physics

    what is the magnitude of the electric field produced by a charge of magnitude 6.00 micro coulombs at a distance of a. 1.00m b. 2.00m

    asked on September 10, 2007
  67. chem

    the pH of a .100 M solution of sodium formate = 8.37. Calculate the value of Ka of formic acid. okay so I know that the anion of a weak acid is itself a weak base so A- +H2O---> OH- + HA pOH =14-8.37 so conc of OH is 10^-5.63 Ka=[OH][HA]/[A-] so we know

    asked on May 13, 2009
  68. physiology

    during the absolute refractory period a supramaximal stimulus can bring the cell to threshold true or false

    asked on October 11, 2008
  69. chemistry

    When the following combustion reaction is balanced using the smallest whole number coefficients, determine the coefficients for oxygen: C(5)H(10)0(2) is reacted with oxygen gas. First of all post the equation with no coefficients.

    asked on May 17, 2007
  70. physics

    why is the total distance traveled by a mass traveling in a circle of radius R during n revolutions =2piRn. The average speed is the distance traveled divided by the elapsed time, so: v=2piRn/delta T, where delta T is the elapsed time.

    asked on March 8, 2009
  71. biology

    why do plants of arid environments have fewer smaller vessels than plants of moist environments?

    asked on May 4, 2008
  72. chem-acid base titrations

    If 20.0mL of .2019M HCI requires 39.63mL of a NaOH solution for complete neutralization, what is the concentration of the NaOH solution? how many significant figures are justified in the answer?

    asked on April 7, 2008
  73. chem

    order the elements Mg, K, Ca, S according to second ionization energy I know that K would have the highest second ionization energy, then come S bec it takes more energy to remove an electron from a nonmetal than a metal, which is next ?

    asked on November 24, 2008
  74. chem-Calorimetry

    If the warm water in this experiment (Im not quite sure if you need more information) is at 98C, how much heat must be relesed in order for the temperature of 100. mL of water to decrease to 32C ?

    asked on March 31, 2008
  75. trig

    Use an addition or subtraction formula to write the expression as a trigonometric function of one number: tan75degrees-tan15degrees/1+tan75tan15=tanAdegrees =square root B Its asking for the value of A and B. I know A =60 degrees, what I can't figure out

    asked on November 15, 2008
  76. muscle physiology

    okay so we did a lab on muscle physiology. acquired one small 2 cm length of psoas muscle . teased the bundle of muscle fibers into individual muscle fibers. aligned 3 individual fibers on each of three different microscope slides and placed 1 fiber on a

    asked on February 24, 2009
  77. trig

    Prove that cos4x=8cos^4x-8cos^2x+1 so I'm guessing you begin with the left side cos4x=cos2(2x) then im kinda lost

    asked on November 23, 2008
  78. evolutionary bio

    following a drought on Daphne Major, the beaks of the offspring of the surviving medium ground finches (average 14mm) were larger than the beaks of the entire population prior to the drought ( 12mm average). Based on the prior study, it is known that the

    asked on June 7, 2008
  79. chemistry

    Na is a metal O, Si, Kr, B are nonmetals Mn is a semimetal why am i getting this wrong ?

    asked on September 9, 2008
  80. Bio

    1. What are the qualities of H bonds? give some examples of H bonds. 2.examples of saturated and unsaturated fats

    asked on May 12, 2008
  81. trig

    how do you solve Fcos29(degree)-210.308-0.58Fsin29=0 Solving for F? F(cos269-.58sin29)=210.308 F= 210.308/(cos269-.58sin29)

    asked on March 14, 2007
  82. physio

    satiety would be induced by all of the following EXCEPT a. cholecystokinin b. naloxone c. morphine d.seratonin I know its not a or c, because those induce satiety. I'm stuck between b and c ...i think its b though

    asked on December 11, 2008
  83. trig

    solve the following equation in the interval [0,2pi]. Give the answer as a multiple of pi. Do not use decimal numbers (sin(t))^2=3/4

    asked on November 22, 2008
  84. physiology

    dizziness during hyperventilation is due to a decrease in cerebral blood flow. The decreased blood flow is caused by a. vasodilation b. decreased stroke volume c.vasoconstriction d. decreased respriation

    asked on November 11, 2008
  85. physiology

    the primary drive to breath is elicited by which of he following: a.reduced PO2 b.reduced PCO2 c.increased PO2 d.increased PCO2

    asked on November 11, 2008
  86. trig

    If tan(x)=8/3 and sin(x)

    asked on September 14, 2008
  87. biology

    In what ways would you expect a fetus to differ from an animal some time after birth?

    asked on April 10, 2008
  88. trig

    Find cosq and sinq if the terminal side of q lies along the line y = - 2 x in quadrant IV.

    asked on December 8, 2008
  89. trig

    Find all solutions of the equation 2sin^2x-cosx=1 in the interval [0,2pi) x1= ? x2=? x3=?

    asked on November 22, 2008
  90. physiology

    Hypotension could be induced by a.excessive renin secretion b.excessive antidiuretic hormone secretion c.excessive aldosterone secretion d.excessive atrial natriuretic factor secretion

    asked on November 11, 2008
  91. chem lab

    ok I'm having trouble with graphing this chemistry lab. It's on atomic emission spectra. In this experiment we observed the line spectrum of first helium, and here is the data: color: distance: wavelenght: violet 20.35cm light blue 21.70cm green 23.08cm

    asked on April 28, 2008
  92. biology lab

    Lab: claim a pot with pea plants in it. If your pot has more than 3 plants, cut if back to three by cutting the extra plants off at ground level. Leave one plant fully intact. With a toothpick flag, label it "C" for control. Cut the apex of the main shoot

    asked on April 3, 2008
  93. physiology

    what drug that is used as a treatment for asthma, promotes bronchodilation by selectively stimulating beta2-adrenergic receptors? A.singular B.albuterol c.Terbutaline d.epinephrine i think its between b and c

    asked on November 10, 2008
  94. Physiology

    Glial cells normally lose their mitotic ability prior to birth True or False Which of the following is NOT a function of astrocytes? a. can take up NT from a synapse b.can stimulate or inhibit neurons c.needed to form synapses in the CNS d.Phagocytose

    asked on October 11, 2008
  95. chem

    why are the atomic emission line spectra different for each element?

    asked on April 14, 2008
  96. Chemistry

    Which of the following products are insoluble in water? a. AgC(2)H(3)0(2) b. MgSO(4) c.Pb(NO3)2 d.Hg(2)CO(3) e.Ca(OH)2 Try looking up the Material Safety Data Sheet for each using google. A useful tip is that all nitrates are soluble in water.

    asked on May 17, 2007
  97. physiology

    Blood flow is increased by a.hypotension b.anemia c.vasoconstriction d.edema I don't see how any of these can be the answer

    asked on November 11, 2008
  98. physiology

    the scientific method is only concerned with experimentation True or False

    asked on September 16, 2008
  99. chem lab

    I'm doing a lab on helium and hydrogen emission spectra. so I got violet 20.35cm blue/green 21.70cm green 22.75 light green 23.08 yellow 27.70 red 31.70 faint red 33.95 and I also have the wavelenghts for helium spectra, its given. like for ex. violet is

    asked on April 28, 2008
  100. chem

    what colored lines are expected in the atomic emission spectrum for mercury?

    asked on April 14, 2008


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