lyne

Most popular questions and responses by lyne
1. chemistry

Nitrogen (N2) and hydrogen (H2) react to form ammonia (NH3). Consider a mixture of six nitrogen molecules and six hydrogen molecules in a closed container. Assuming the reaction goes to completion, what will the final product mixture be? number of NH3

2. chemistry

The total acidity in water samples can be determined by neutralization with standard sodium hydroxide solution. What is the total concentration of hydrogen ion, H+, present in a water sample if 300. mL of the sample requires 7.5 mL of 2.8 10-3 M NaOH to be

3. chemistry

The element rhenium (Re) has two naturally occurring isotopes, 185Re and 187Re, with an average atomic mass of 186.207 amu. Rhenium is 62.60% 187Re, and the atomic mass of 187Re is 186.956 amu. Calculate the mass of 185Re. am i supposed to multiply the

4. chemistry

Hydrogen cyanide is produced industrially from the reaction of gaseous ammonia, oxygen, and methane. 2 NH3(g) + 3 O2(g) + 2 CH4(g) 2 HCN(g) + 6 H2O(g) If 5.00 x 10^3 kg each of NH3, O2, and CH4 are reacted, what mass of HCN and of H2O will be produced,

5. chemistry

a.Write the balanced chemical equation for the reaction of methane and sulfur. (Type your answer using the format CO2 for CO2. Use the lowest possible coefficients.) 1CH4 + 4S --> 1CS2 + 2H2S (b) Calculate the theoretical yield of carbon disulfide when

6. chemistry HELP

A 46.2 gram sample of copper is heated to 95.4 degrees celcius and then place into a calorimeter containing 75.0 grams of water at 19.6 degrees celcius. The final temp of the water and copper is 21.8 degrees celcius. Calculate the specific heat capacity of

7. chemistry

Ca(s) + Br2(l) --> CaBr2 is synthesis my teacher also said that the cause of the reaction is stable electron configuration is that the same thing as the electrolytes one

8. chemistry

A student prepared aspirin (C9H8O4) in a laboratory experiment using the following reaction. C7H6O3 + C4H6O3 C9H8O4 + HC2H3O2 The student reacted 2.00 g salicylic acid (C7H6O3) with 2.67 g acetic anhydride (C4H6O3). The yield was 2.00 g aspirin. Calculate

9. chemistry

Consider the following unbalanced reaction. P4(s) + 6F2(g) 4PF3(g) How many grams of F2 are needed to produce 114. g of PF3 if the reaction has a 78.1% yield? i tried it and got this 114g PF3 x (mol PF3/87.97g PF3) x (6 mol F2/ mol PF3) x (38g F2/mol

10. chemistry again :)

A compound containing only sulfur and nitrogen is 69.6% S by mass; the molar mass is 184 g/mol. What are the empirical and molecular formulas of the compound? i solved for empirical and got a 1:1 ratio so it would be SN. for the molecular do i take

11. math

Define variables and write a system of equations for each situation. Solve using substitution. Suppose you are thinking about buying one of two cars. Car A will cost \$17,655. Youn can expect to pay an average of \$1230 per year for fuel, maintenance, and

12. chemistry

#2) Consider the preciditation reaction of a solution containing 3.50 grams of sodium phosphate mixed with a solution containing 6.40 grams of barium nitrate. How many grams of Barium phosphate can form? Ba(NO3 )2 + Na3 PO4 yields Ba3 (PO 4 )2 + NaNO3 #2b)

13. chemistry

What volume of .101 M HNO3 is required to neutralize each of the following solutions? there are four and i got them all right but this one... 51.1 mL of .127 M NH3 i got 193 mL can someone please help???

14. chemistryy

Most window cleaners are aqueous solutions of ammonia. A 9.00 mL sample of a particular window cleaner requires 42.95 mL of 0.0508 M HCl for its titration. What is the molarity of ammonia in the window cleaner? i am completely lost i cant even find the

15. chemistry

Aspirin (C9H8O4) is synthesized by reacting salicylic acid (C7H6O3) with acetic anhydride (C4H6O3). The balanced equation is given below. C7H6O3 + C4H6O3 C9H8O4 + HC2H3O2 What mass of acetic anhydride is needed to completely consume 3.60 x 10^2 g salicylic

16. chemistry

why is COCl2 polar a. different electronegativities b. nonsymmetric c. tetrahedral d. symmetric e. trigonal planar more than one can be chosen also wht is HCN polar a. nonsymmetric b. different electronegativities c. trigonal planar d. linear e. bent f.

17. chemistry

Ca + Br2 --> CaBr2 its synthesis and the reason the reaction happens is stable electron configuration but i don't understand why. Responses chemistry - DrBob222, Wednesday, January 21, 2009 at 10:06pm Synthesis because it's two elements combining to form a

18. chemistry

How many grams of oxygen are required to react with 2.50 g of propane (C3H8) to form CARBON MONOXIDE and water? this is what i did why is it wrong? 2.50 g C3H8 x 1 mole / 44.09 g C3H8 x 5mole O2 / mole = 9.1 g O2 everything cancels to get grams of O2 which

19. chem

which element has a more favorable (exothermic) electron affinity? K Mg how do i determine this?

20. chemistry

Calculate the number of C, H, and O atoms in 4.50 g of glucose (C6H12O6), a sugar. okay i did it and i got just the C right and not the H and O help?

21. Science

what does the geologic time scale indicate about the change in life-forms over time?

22. chemistry

predict the identity of the precipitate that forms. calcium nitrate, Ca(NO3)2, and sodium chloride , NaCl why does the answer come out as no reaction? couldnt it form to be CaCl2 or NaNO3 i thought it had something to do with the fact that Na and NO3 are

23. chemistry

how many atoms of tungsten are in 504.56 g of tungsten(IV)acetate. i attempted this problem but ended up with atoms of tungsten(IV) acetate in tungsten(IV) acetate instead of atoms of just tungsten in tungsten(IV) acetate. please help thanks

24. chemistry

Write a chemical equation showing how each of the following species behaves as a base when dissolved in water a.) O2- i have O2- + H2O --> HO2- + OH- how do i make this right??

25. chem

what VSEPR "shapes" and bond angles do you find Toluene

26. chemistry

Calculate the hydrogen ion concentration and the pH of each of the following solutions of strong acids. (a) 0.00010 M HCl if you could just explain how to do this that would be great! thanks

27. chemistry

how many moles of hydroxide ions are there in 82.35 mL of a 2.164M Sr(OH)2 solution? i understand how to do the math for problems like these, but i don't know how to find the moles of just hydroxide ions.

28. chem

a certain substance strongly absorbs infrared light having a wavelength of 3.75µm. what is the frequency of this light in hertz? i know that i have to use the equation c = frequency x wavelength and that c = 2.998 x 10^8 m/s. how do i convert that to

29. chemistry

calcium hydroxide reacts in a neutralization reaction with sulfuric acid in a 1:1 ratio to form water and calcium sulfate. if you have 23.5 grams of calcium hydroxide, how many milliliters of water can you form? how do i use dimensional analysis to solve

30. chemistry

How do multiple bonds introduce rigidity into molecules? what is meant by rigidity??

31. chemistry

Chlorine dioxide, ClO2, has been used as a disinfectant in air conditioning systems. It reacts with water according to the following equation. 6ClO2 + 3H2O --> 5HClO3 + HCl If 142.0 g of ClO2 is mixed with 33.0 g of H2O, how many grams of the reactant will

32. chemistry DRBOB

Calculate the hydrogen ion concentration, in moles per liter, for solutions with each of the following pH values. pH=1.10 im guessing that this is what i did in my previous question except now i have to do it backwards. but i don't know how to do the

33. chemistry

How would you prepare 250.0 ml of a 0.6 M aluminum sulfate solution

34. chemistry

When ammonia gas is burned in oxygen the products formed are water and nitrogen monoxide gas. Write the balanced equation showing this reaction NH4 + O2 --> H2O + NO i am stuck balancing this

35. chemistry

Ca + Br2 --> CaBr2 its synthesis and the reason the reaction happens is stable electron configuration but i don't understand why.

36. chemistry

how do i balance the following(fill in the blanks): 1.) __BF3 + __Li2SO3 --> __B2(SO3)3 + __LiF 2.) __CaCO3 + __H3PO4 --> __Ca3(PO4)2 + __H2CO3 3.) __B2Br6 + __HNO3 --> __B(NO3)3 + __HBr

37. chemistry 1

k2=[H][SO4]/[HSO4] .012=(.01+x)(x)/(.01-x) Solve for x, and calculate pH where H is .01+x When I am solving for x does it become .012= .01x + x^2/ .01 -x.. what is the next step of solving for x?

38. chemistry

I have to draw the QMM of CL2C2. For the Lewis structure i think that the two C atoms form a triple bond and the Cl atoms form single bonds. Cl | C'triple bond'C | Cl Therefore i think that the central C atom hybridizes into sp. if this is correct, my

39. CHEMISTRY

How much water should be added to 45.0 mL of 0.225 M HCl to dilute the solution to 0.155 M? i did .225M x .045L / .155M = 65mL so wouldnt 20 mL be added?

40. chemistry

continued from before.... the question was what are three chemical characteristics and ten physical characteristics so then would i have to say something like -when iron rusts or -sugar burns or something like that i was thinking that would just be a

41. chemistry

The compound adrenaline contains 56.79% C, 6.56% H, 28.37% O, and 8.28% N by mass. What is the empirical formula for adrenaline? i worked the problem out and got C8O3N but its not right..what did i do wrong?

42. Gen Chemistry

What is the pH ( 3 significant digits) of a 0.01 M solution of sulfuric acid? Hint is that the first ionization constant is "large", and the second is finite, and the [H+] donated by the second equilibrium depends upon the amount of [H+] already donated by

43. chem

if you were to react 14.00 grams of salicylic acid with 8.50 grams of acetic anhydride, what would your theoretical yield be? the reaction is C7H6O3+C4H6O3--> C9H8O4 + C2H4O2 assuming 1:1 ratio.

44. chem

how many grams of a precipitate will form when you mix 45 ml of a 3.5M silver nitrate solution with 45 ml of a 5.4 M magnesium chloride solution i sorted the problem but have no clue how to start

45. chemistry

what is the duet rule?

46. Science

how did geologists determine the divisions of the geologic time scale?

47. chemistry HELP DRBOB

Calculate the sodium ion concentration when 80.0 mL of 4.5 M sodium carbonate is added to 30.0 mL of 1.0 M sodium bicarbonate. how do i solve this I don't really know where to begin.. is there a formula for finding concentration because we don't learn this

48. chemistry

How much of each starting material would you use to prepare 2.00 L of each of the following solutions? 0.240 M NaOH from 1.00 M NaOH stock solution what do i do with the .100 M and .240 M??

49. chem

how do you prepare a solution using the proper lab equipment(both from dry solid and a stock solution) i researched it but all i found was the definition for stock solution any help please!!

50. chemistry -IMPORTANT-

we have to make an instrctinal packet showin relationships between moles and concentration. i cant find the following 1)how is the number of moles dissolved in a set amount of solvent related to the molarity? 2)how to determine the amount of solvent in

51. chemistry

3BaCl + 2Na3PO4 --> Ba3(Po4)2 +^NaCl is Ba3(PO4)2 the ppt. because Cl salts are soluble so it will dissolve?

52. chemistry

NaCl + CuSO4 to write the product would i just do double replacement to get Na2SO4 + CuCl2 so the whole thing would be 2NaCl + CuSO4 --> Na2SO4 + CuCl2

53. chem

sorry for all the questions i have an exam tomoro! but what is intrinsic or intensive are they the same?

54. chem

how many protons, nnutrons, atomic mass, mass number, and charge to each of the following have? sodium atom fluorine ion stannic ion for sodium i have protons=11 electrons=11 neutral charge how do i find the number of neutrons cause im pretty sure mass

55. chemistry

Calculate the number of C, H, and O atoms in 4.50 g of glucose (C6H12O6), a sugar. help please?

56. chemistry

Posted by lyne on Tuesday, March 25, 2008 at 11:44pm. What is the pH ( 3 significant digits) of a 0.01 M solution of sulfuric acid? Hint is that the first ionization constant is "large", and the second is finite, and the [H+] donated by the second

57. chemistry

What is the pH ( 3 significant digits) of a 0.01 M solution of sulfuric acid? Hint is that the first ionization constant is "large", and the second is finite, and the [H+] donated by the second equilibrium depends upon the amount of [H+] already donated by

58. math URGENT

okay i need to find the domain and range of this z(x) = ãx^2 - 100 (everything is in the square root) so i think i found the domain i got [-10,10] but i don't know about the range i solved for x and got stuck here x=ãy^2 + 100 helppp pleaseee :)

59. chemistry

mole can be abreviated as mol right??

60. chemistry

what ionic compounds could you form from the following? Sodium Calcium Neon Phosphorus Chlorine i have NaCl, CaCl2, Na3P, and Ca3P2 is that all and can neon be used?

61. CHEMISTRY HELP

NH3 + HCl --> can someone please finish that?? is it 2H2 + N2 + Cl or something? if so how would i balance it?

62. chemistry

If the volume of solute is 6 ml and the volume of the solution is 300 ml, what is the solute's percent by volume? is it solute/solution so % = 6/300 so then would it be % = .02 would i change it to 2%???

63. Chemistry Web Quest

How do you recover the dissolved solid in a solution?

64. chemistry

we did a lab where we mixed an iron nail with cupric chloride to find the reaction is this the balanced equation... Fe + CuCl2 --> FeCl2 + Cu or would Fe and Cl bond different??

65. math

what is the function rule for this figure sides- 3 4 5 6 7 diagonals- 0 2 5 9 15

66. chemistry

i did a lab and found that of the products two gases were formed H2 and H2CO3 the question is... What are the tests that will verify the identity of these gases? what is this asking?

67. chemistry

What does it mean to say that the ions of an electrolyte behave independently of one another when the electrolyte is dissolved in water? is it something about the compound splitting?

68. chemistry

arent the allotropes of carbon diamond buckminsterfullerene(or whatever its called haha) and graphite?

69. math

how many mL in .00670 grams of a substance that has a density of 1.96 g/cm3. do you do 1.96g/cm3 divided by .00670 grams to solve for cm3 since cm3 = mL

if you have 55.6 grams of nitrate ions in a compound that consists of nitrate ions and plumbous ions, how many grams of the compound do you have? how do i do this problem im completely stuck!?

71. chem

DrBob has given you the equation to use: k2 = [H^+][SO4^-]/[HSO4^-] and the values to substitute [H^+] = 0.01 + x [SO4^-2] = x [HSO4^-] = 0.01 - x k2 = 1.2 x 10^-2 you need to substitute these and solve for x. Remember that you are after 0.01+x [H^+] to

72. math

Next step, multiply both sides by (.01-x) .012(.01-x)=.01x+x^2 is the binomial x^2 + .002x-1.2x10^-4 what is the next step is the answer -.021 and -.023 for x

73. chem

Next step, multiply both sides by (.01-x) .012(.01-x)=.01x+x^2 gather terms, put in standard binomial form, use the quadratic equation, and solve for x. is the standard binomial x^2+.022x-1.2x10^-4

74. chem

What is the pH ( 3 significant digits) of a 0.01 M solution of sulfuric acid? Hint is that the first ionization constant is "large", and the second is finite, and the [H+] donated by the second equilibrium depends upon the amount of [H+] already donated by

75. math

i already asked this question for how to divide (x^2 +2x) / 2x-1 i need to find the quoyient not how to simplify it. I need to use the quotient in order to graph an oblique asymptote. can it not be divided?

76. math

how would i do (x^2 + 2x) / (2x-1) thanks

77. math

what would the graph of this look like xy

78. microbiology

what is the common-source outbreak of the H1N1 flu of 2009

79. math

ok this is kinda stupid but i totally just confused myself with the simplest thing haha okay when doing the FOIL methed to this equation (-7-y)(-7-y) would it be 49 + 7y + 7y + y^2 or no??

80. science

are most petri dishes the same size? if so what would the diameter of one be? i need to find the surface area of a petri dish

81. ..

are most petri dishes the same size? if so what would the diameter of one be? i need to find the surface area of a petri dish

82. microscopes

When using a light microscope to look att two hairs crossed over each other... Under low power were both hairs in focus at the same time? What about medium power? What does this tell you about the depth of field as you increase magnification. The answer to

83. Microbiology

what is the best resolution of our light microscopes the formula should be RP = wavelength/2NA right?? so my question is which wavelength do i put as the denominator

84. chemistry

list three ions that are iso-electric with potassium +1 please explain i have no clue

85. chemistry

my teacher told me that polar bonds have a difference in elecronegativities of .4-2.1 is that the only way to find if a bond is polar? also how would you find out if the MOLECULE is polar or not? - i think i remember my teacher saying something about

86. chemistry

what are structural formulas?? also is this correct hybridization is the setting aside of p orbitals in order to form bonds (pi bonds)

87. DRBOB

help with below questions please and thank you

88. chemistry

I have to draw the QMM of CL2C2. For the Lewis structure i think that the two C ayoms form a triple bond and the Cl atoms form single bonds. Therefore i think that the central C atom hybridizes into sp. if this is correct, my question is how do i know

89. chemistry

when do you need to use the octet rule for lewis structures and when does it not apply i am confused for N2O4 i cant get the rules to work with the structure

90. chemistry

Why are all diatomic molecules diatomic molecules linear, regardless of the number of valence electron pairs on the atom? i don't understand this question what is meant by linear?

91. chemistry

okay we are drawing bonds and i was wondering how i am supposed to know if you can make a double or triple bond for example for NH2OH why cant i make the bond between N and O triple instead of leaving lone pairs.. thanks

93. chemistry

Solutions that have large amounts of solute are___ solutions that have small amounts of solute are ___

94. math

function rule for tis points- 1 2 3 4 lines- 0 1 3 6 its similar to an earlir one i posted but i still don't quite understand thanks

95. Dr Bob

okay and i don't understand what they are asking for for chemical characteristics. i was thinking like density, melting point, and boiling point but arent those physical too?

96. chemistry

what are three chemical characteristics and ten physical characteristics so far for physical i have -color -taste -smell -size -luster -shape -texture is this what they are asking for?

97. c++

what would the the answer to 55%7 be?

98. CHEMISTRY HELP

if you have 55.6 grams of nitrate ions in a compound that consists of nitrate ions and plumbous ions, how many grams of the compound do you have? how do i do this problem im completely stuck!?

solve for the variable ã(square root) ãy+6 - ãy = ã2 would i square both sides first? im stuck