Thursday
December 8, 2016

Posts by K

Total # Posts: 905

**CHEM**
this order came up being correct. Thank you
November 13, 2007

**CHEM**
Arrange the following elements in order of decreasing atomic radius: Cs, Sb, S, Pb, Se *(list from largest to smallest...or..."the correct ranking cannot be determined") ***I think the answer 'should be', from largest to smallest: ***Cs, Pb, Sb, Se, S***???? ...
November 13, 2007

CHEM
the 4th one was correct as well. Thank you!
November 13, 2007

CHEM
Could someone please tell me if I am correct on the following???: Pick the larger species from each of the following pairs. Sr or Sr^2+ *(I think it is Sr) N or N^3- *(I think it is N^3-) Ni or Ni^2+ *(I think it is Ni) S^2- or Ca^2+ *(I think it is S^2-)
November 13, 2007

CHEM
Z wasn't correct. Element Z has a larger radius than elements X and Y. Because the outer electrons of element Z are not attracted as tightly to the nucleus as the outer electrons of elements X and Y, we can expect element Z to have a lower first ionization energy than ...
November 13, 2007

CHEM
Which of the following elements has the highest first ionization energy? Element then radius (pm): X = 105pm Y = 175pm Z = 274pm I think that the answer is "Z-274pm", but I just would like to make sure.
November 13, 2007

CHEM
Consider the following neutral electron configurations in which 'n' has a constant value. Which configuration would belong to the element with the most negative electron affinity, E-ea? a) ns^2 b) ns^2 np^2 c) ns^2 np^5 d) ns^2 np^6 would the answer be "d"...
November 13, 2007

CHEM
Consider the relation shown for the radius of the species indicated. Which choice presents a valid comparison? a) Na > Na+ b) Ca^+2 > Ca+ c) Cl > Cl- d) S- > S^2- I think that the answer is "a"...but not 100% certain. pls help.
November 13, 2007

CHEM
if you were to draw a Lewis dot structure for HOCl...would it be H:Cl:O: (with double dots above & below the Oxygen & Chlorine) or would it be: H:O:Cl: (same thing for the double dots being above & below the Cl & O? Basically...is Oxygen the central atom in this case or is Cl ...
November 10, 2007

CHEM
WOOO! 3.12*10^4 came to be correct indeed! Thank you ever so much for your time & patience.
November 5, 2007

CHEM
so just divide by 1000? I tried that when I had 5.19*10^-20 & it told me I was incorrect? or did you mean to divide somewhere else along the way?
November 5, 2007

CHEM
where am I going wrong?
November 5, 2007

CHEM
apparently 5.18*10^-17 kJ/mol isn't the correct answer either.
November 5, 2007

CHEM
Soooo??? KE = hc/lambda - 1.602*10^-19J*956eV?? 6.6261*10^-34*3.0*10^8 / 9.7*10^-10m minus 1.53*10^-16?? =5.19*10^-17??? That can' be right??
November 5, 2007

CHEM
the answer came to 3.2*10^-35m. I kept typing the values into the calculator wrong. I multiplied the 765m/s, rather than dividing. I still don't understand the other question though. Q#2.
November 5, 2007

CHEM
I just have a couple of questions that I need some help with: 1) A 0.22-caliber handgun fires a 27g bullet at a velocity of 765m/s. Calculate the de Broglie wavelength of the bullet. Express your answer using two significant figures in meters. ~and~ 2) An X-ray photon of ...
November 5, 2007

CHEM
2.0*10^-34 was correct. Thank you.
November 5, 2007

CHEM
so...would I find the answer to be: lambda=6.626*10^-34 J s/(0.0459kg)(72.0m/s) answer= 2.00*10^-34 or should I have squared the 72.0m/s velocity?
November 5, 2007

CHEM
The mass of a golf ball is 45.9g. If it leaves the tee with a speed of 72.0 m/s, what is its corresponding wavelength? Express your answer numerically in meters. Would the correct answer be: lambda=h/mv lambda=6.626*10^-34/(45.9g)(72.0m/s) lambda=2.00*10^-37 ??? Is the ...
November 5, 2007

unsramble words
1. secret 2. search 3. new finder?? 4. dwindce?? dwinced??...not sure if those are words so much.
November 4, 2007

CHEM
guess it was correct... the real answer, rounded though, came to be: -2.05*10^-18J thank you.
November 4, 2007

CHEM
I used: E = -(Rhc)/n^2 R= 1.097*10^7 m^-1 h= 6.6261*10^-34 J s c= 3.00*10^8 m s^-1 E= -(1.097*10^7)(6.6261*10^-34)(3.00*10^8)/16 E= -1.36*10^-19 J so I just use final minus initial? How so? when I do the same as above...but put in 1squared=1, rather than 4squared=16.. I get: -...
November 4, 2007

CHEM
The electron from a hydrogen atom drops from an excited state into the ground state. When an electron drops into a lower-energy orbital, energy is released in the form of electromagnetic radiation. Part A: How much energy does the electron have initially in the n=4 excited ...
November 4, 2007

CHEM
thank you..I reworked it & the answer came to: 0.73%.
November 4, 2007

CHEM
The mass of an electron is 9.11*10^-31kg. If the de Broglie wavelength for an electron in a hydrogen atom is 3.31*10^-10m, how fast is the electron moving relative to the speed of light? The speed of light is 3.00*10^8m/s. Express your answer numerically as a percentage of the...
November 4, 2007

economics
Where does Bexar County rank among texas counties in per capita income? <br><br> Where does Cameron County rank among texas counties in per capita income? <br><br> what was the inflation rate in hungary in 1945-1946?
October 30, 2007

Lunch
take some almonds as a snack throughout the day. As for lunch, take a balanced lunch = with some fruit for dessert, ex.an apple or pear or something of the sort. Main course could be something like a turkey sandwich on whole wheat, or on a whole wheat begal if you so choose. ...
October 29, 2007

CHEM
i mean... 0.574L didn't work.
October 29, 2007

CHEM
Butane, C4H10, is a component of natural gas that is used as fuel for cigarette lighters. The balanced equation of the complete combustion of butane is: 2C4H10(g) + 13O2(g)->8CO2(g) + 10H2O(l) At 1.00atm and 23*C , how many liters of carbon dioxide are formed by the ...
October 29, 2007

CHEM
I worked the info above out &, yes, your thinking was indeed correct. Thank you heeps.
October 28, 2007

CHEM
I tired 7.79g of He added & it told me this: This number looks like the final mass of He multiplied by 2. Instead, find the difference between the final and initial masses.
October 28, 2007

CHEM
A cylinder with a movable piston contains 2.00g of helium, He, at room temperature. More helium was added to the cylinder and the volume was adjusted so that the gas pressure remained the same. How many grams of helium were added to the cylinder if the volume was changed from ...
October 28, 2007

CHEM
well...I managed to use the correct equation: M=mRt/PV...& the answer came to Ar. Thank you very much!!
October 28, 2007

CHEM
the only prob left is: do I just add the variables? or which ones do I take into account? PV=nRT n=RT/PV...or should I be using: M=mRT/PV???
October 28, 2007

CHEM
#2= 1.61atm:)
October 28, 2007

CHEM
ok...I tried my answer...I got the first part correct..it was actually 0.455atm.
October 28, 2007

CHEM
for Part 1: would the P2 just be 0.454 atm then? I went: P1*V1=P2*V2 then: P2=P1*V1/V2? So...1atm*1L/2.20L = P2= 0.454atm??
October 28, 2007

CHEM
A) a picture shows a container that is sealed at the top by a movable piston. Inside the container is a ideal gas at 1.00atm , 20.0 *C, and 1.00L. (The pic is of a 2L container which has a piston pushed downward to the 1L level. Under the piston, under the 1L mark, is a sample...
October 28, 2007

CHEM
thank you!
October 21, 2007

CHEM
Thank you muchly!! (the questions are just from an old MT that we were to go over to study for the real MT this coming Sat.)
October 21, 2007

CHEM
so for #14 I got: 4mols #16: 1.0mL #17...the other two choices were b-0.1MCH3COOH & then d) both A&B, that's why I didn't bother putting them in, considering b is not an electrolyte. #25: b- HCl? #2, about Av's #...the options were: a)the # of Hydrogen atom in ...
October 21, 2007

CHEM
I was just wondering if someone would be able to critique my answers for the following Chem questions? they range from pretty basic to a bit more... 2)which of the following is the definition of the value of Avogadro's constant: b) the # of Carbon atoms in exactly 12g of ...
October 21, 2007

ECON-HELP!!
% Change in M + % Change in V = % Change in P + % Change in Y. i.e, % Change in P = % Change in M + % Change in V – % Change in Y. % Change in P = 14% + 0% – 5% = 9%. % Change in P is the inflation rate π. From the Fisher equation, we have i = r + π, i is ...
October 21, 2007

Science
What would be the likely function of a plant cell containing many chloroplasts?
October 18, 2007

CHEM
Help on part "c": The forensic technician at a crime scene has just prepared a luminol stock solution by adding 19.0g of luminol into a total volume of 75.0mL of H2O. a)What is the molarity of the stock solution of luminol? answer I got: molarity of luminol solution...
October 18, 2007

CHEM
this answer, 83.9mL worked...thank you for the guidance.
October 18, 2007

CHEM
Help on part "c": The forensic technician at a crime scene has just prepared a luminol stock solution by adding 19.0g of luminol into a total volume of 75.0mL of H2O. a)What is the molarity of the stock solution of luminol? anwer I got: molarity of luminol solution...
October 18, 2007

CHEM-last part prob.
(oh...slightly dislexic...yes...I meant 0.225 moles, that would have helped if I had noticed before & typed it in correctly.)
October 16, 2007

CHEM-last part prob.
ok...so I shouldn't have multiplied through by 2. That makes a lot more sense. Thank you, yet again, and it came out alright.
October 16, 2007

CHEM-last part prob.
I tried this answer & it was incorrect.
October 16, 2007

CHEM-last part prob.
Aluminum reacts with chlorine gas to form aluminum chloride via the following reaction: 2Al(s) + 3Cl2(g) -> 2AlCl3(s) You are given 19.0g of aluminum and 24.0g of chlorine gas. a)If you had excess chlorine, how many moles of of aluminum chloride could be produced from 19.0g...
October 16, 2007

CHEM
I kept trying it, via comparing it to a, & finally did come up with 0.255mol AlCl3...I had just gotten the question incorrect,somehow, 4x...so I had to ask. Thank you for your patience with me. I will be looking into getting a tutor shortly.
October 15, 2007

CHEM
Aluminum reacts with chlorine gas to form aluminum chloride via the following reaction: 2Al(s) + 3Cl2(g) -> 2AlCl3(s) You are given 19.0g of aluminum and 24.0g of chlorine gas. a)If you had excess chlorine, how many moles of of aluminum chloride could be produced from 19.0g...
October 15, 2007

CHEM
it worked out beautifully. Thank you!
October 15, 2007

CHEM
My balanced equation is: a) 2C8H18(g) + 25O2(g) -> 16CO2(g) + 18H2O(g) b) 0.290 mol of octane is allowed to react with 0.670mol of oxygen. Which is the limiting reactant? (((Which I found Oxygen to be the limiting reactant.))) I do not understant how to work out "c&...
October 15, 2007

CHEM
THIS time I got it correct! answer = 5.13x10^-19 molecules! THANK YOU soooo much!! I only had 2 attempts remaining!
October 15, 2007

CHEM
How many molecules of ammonia are produced from: 2.58x10^-4g of Hydrogen? My balanced equation: 3H2 + N2 = 2NH3 I worked this question as: mol of H = 2.58x10^-4g/1.00794g/mol= 2.559676x10^-4 mol mol of NH3 produced = 2x2.559676x10^-4mol/3mol NH3 = 1.706450701x10^-4 Molecules...
October 15, 2007

CHEM
Calculate the mass (in grams) of the product formed when 10.1g of the underlined reactant completely reacts. Assume that there is more than enough of the other reactant. 2K(s) + __Cl2(g)__ -> 2KCl(s) I cannot get the correct answer.
October 15, 2007

CHEM
A scientist wants to make a solution of tribasic sodium phosphate,Na3PO4 , for a laboratory experiment. How many grams of Na3PO4 will be needed to produce 575mL of a solution that has a concentration of Na^+ ions of 1.40 M? Answer: mass of Na3PO4 = _____ How is this question ...
October 15, 2007

CHEM
My question doesn't have to be answered. I figured out what they were asking and got it correct.
October 15, 2007

CHEM
For the reaction shown, find the limiting reactant for each of the following initial amounts of reactants. 4Al(s) + 3O2(g) -> 2Al2O3(s) 4mol Al, 2.6mol O2? a) 4mol Al, b) 2.6mol O2. I seriously have no idea what they are asking! What do you do with the 4mol Al & 2.6mol O2...
October 15, 2007

CHEM
does this sound correct? 8.00X10^-4 kg?
October 15, 2007

CHEM
I am still not quite grasping how to complete this problem: Posted by K on Sunday, October 14, 2007 at 6:43pm. Many home barbeques are fueled with propane gas C3H8. What mass of carbon dioxide (in kg) is produced upon the complete combustion of 18.9L of propane (approximate ...
October 15, 2007

CHEM
Many home barbeques are fueled with propane gas C3H8. What mass of carbon dioxide (in kg) is produced upon the complete combustion of 18.9L of propane (approximate contents of one 5-gallon tank)? Assume that the density of the liquid propane in the tank is 0.621g/ml. How do I ...
October 14, 2007

banking
two words: aehoumncrrusse
October 1, 2007

chem
A&B worked...thank you
September 24, 2007

chem
it has to be choose all that are possiblities. Do you think that a and b then are the best choices? E and G def. are not, agreed.
September 24, 2007

chem
A blood sample contains several different types of cells, each of which contains different combinations of specific ions and molecules. The cells are suspended in water, and the water also contains many molecules and ions. Which term or terms could be used to describe this ...
September 24, 2007

English
thank you so much!!! you really helped!
September 21, 2007

English
What's the difference between the following sentences: "he looks happy." "he looks like he's happy." "he seems happy."
September 21, 2007

maths
how wod i solve the following two eqautions? either exactly or to 3 significant a)2^x = 5 b)3^x+1 = 7 i know a) is 2.32 and b) is 0.771 but i don't know how to show it out step by step in how i worked it out . can sum1 plz help me You have to use logs, and learn how to do ...
August 14, 2007

art
why do artist use parallel lines that do intersect?? Thank you for using the Jiskha Homework Help Forum. Here is a definition of parallel: extending in the same direction, everywhere equidistant, and not meeting Just what art are you referring to? Parallel lines do not ...
July 30, 2007

lines
] A printed capital letter names a:
July 28, 2007

geometery
[1.04] If B is between A and C, AB=2x-1, BC=3x+5 and AC=24, what is the value of x? Segment A C contains point B. *A=======B======*C If AC = 24; AB = 2x-1 and BC = 3x+5, then AB + BC = AC. Solve for X. Post your work if you get stuck. (2x -1) + (3x +5) = 24 5x +4 = 24 5x = 20 ...
July 28, 2007

maths
A town planner is using a map of a town centre with a scale of 1: 1250 A path in the town is 8cm long on the map. How long is the path in the town? Give your answers in metres. how do i work this out?? set up the proportion: 1/1250 = 8/x x=1250*8 cm = 10000 cm =100 m
May 9, 2007

science
The specific heat capacity of the lava is 1600 J kg -1 degrees Celsius -1 . When all the erupted lava cools from the eruption temperature of 1050 degrees Celsius to 15 degrees Celsius, the heat released is 2 x 10 15 J. Calculate a value for the total mass of lava that erupted...
May 9, 2007

Chemistry
Even though it's been years, 8.58 x 10^-4 M would be the standardized solution of KMnO4. This is usually given by the lab instructor at the beginning of the experiment.
May 7, 2007

maths
The head of an industrial machine moves in a straight line horizontally backwards and forwards from a central position. The movement can be modelled using the sine wave d = 80 sin ( pie t), where d is the horizontal distance (in cm) from the central starting position, and t is...
May 6, 2007

maths
The head of an industrial machine moves in a straight line horizontally backwards and forwards from a central position. The movement can be modelled using the sine wave d = 80 sin ( pie t), where d is the horizontal distance (in cm) from the central starting position, and t is...
May 6, 2007

Science
As each organism eats each other they transfer energy!! I'm doing the same thing lol
May 5, 2007

science
hi, could any1 tell me in basic words on "the environment and process of formation of schist and sandstone?? Since this is not my area of expertise, I searched Google under the key words "'formation process' schist sandstone" to get these possible ...
April 25, 2007

maths
The head of an industrial machine moves in a straight line horizontally backwards and forwards from a central position. The movement can be modelled using the sine wave d = 80 sin ( pie t), where d is the horizontal distance (in cm) from the central starting position, and t is...
April 23, 2007

Economics
What changes, if any, to the current condition of these tools would you make at the next meeting of the Federal Reserve? Explain why and the benefits/drawbacks of this strategy. You seem to have omitted part of the questin. What tools are you talking about? Monetary policy ...
March 16, 2007

Science Question 1
terrestrial
March 5, 2007

Biology
Hi, I have 4 questions regarding Biology. 1. Does a different chromosome number in two species represent a significant difference? 2. Chromosome 7 has an extra band at the top in chimpanzees; does this extra band affect the quantity of coding DNA? And does it make a ...
February 21, 2007

Chemistry (Check)
there are seven base units not five
January 18, 2007

Algebra
How do you solve for x in this problems?? bx-2=10 x/2+e=9 5x+e=9 These are rather trivial. I will do one. The second: subtract e from both sides, then multiply both sides by 2.
January 18, 2007

decision making
Your manager is concerned and wants to make sure that you learned from this mistake and the likelihood of this happening in the future is minimal. Therefore she would like you to email her a reflective analysis about that decision. Be sure to address the following in your ...
January 11, 2007

math
Write in decimal form.94 17/ 1,000
January 5, 2007

CHEM
in addition to previous Q: for eg: why is the oxidation state (#) of Ca in CaH2 "+2"? According to a p.table I have here +2 is the only oxidation # for Ca...but how is that figured? One other eg: the oxidation state (#) of the maganese atom in KMnO4.6H2O is "+7&...
December 14, 2006

CHEM
What is the exact method/formula used to calculate oxidation state #'s? & how does one know when to use the correct oxidation state #? For example: Carbon carries 4,2,-4; Cl= 1,5,7,-1; and, Mn=2,3,4,7. Thanx. You use the seven rules in your text. Assigning of the oxidation...
December 14, 2006

CHEM
A gaseous hydrocarbon (an organic compound consisting of C & H) weighing 0.232g occupies a volume of 102mL at 23 degrees Celcius and 749mmHg. Calculate the molar mass and identify the compound. The compound is: a)C2H4 b)C3H6 c)C4H8 d)C5H10 e)C6H12 How is this problem worked ...
December 13, 2006

CHEM
thank you VERY much for your replies, DrBob. Another question, however: How many moles of ions -both cations and anions- are present in solution when 0.75 mol of potassium chloride is dissolved in 0.25L of distilled water? How do I work this answer to be: 1.5mol? KCl(s) + H2O...
December 12, 2006

CHEM
how do I work this question out?: 50.00g of NaCl are dissolved in water to give a solution that contains 2.500% NaCl by mass. The density of the solution is 1.030g/mL. The volume of the solution is: a)941.8mL; b)1.942L; c)2.500L; and, d)50.0mL. I know the answer is "b&...
December 11, 2006

Math
Find X 27^4x-2=243^3x=6 Please Explain Thanks Is this a repeat of the problem you posted earlier? If so, it should be 274x-2 = 2433x+6 You might try it the hard way. (4x-2)*log 27 = (3x+6)*log (243) Solve for x. I get -12. Post your work if you get stuck. You have too many = ...
November 28, 2006

Math
Find X 27^4x-2=243^3x+6 Please explain how to do it. Thanks 27^(4x-2)=243^(3x+6) Notice that 27 and 243 are both multiples of 3 Changing them.. (3^4)^(4x-2)=(3^6)^(3x+6) 3^4(4x-2)= 3^6(3x+6) taking the log base 3 of each side. (4x-2)= (3x+6) and solve for x. That doesn't ...
November 28, 2006

Chem
what is NH3 in written form? ammonia As a note, it is becoming more and more common to see ammonia written in IUPAC form, H3N, and the ammonium Ion written as H4N+
November 17, 2006

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