Thursday
December 18, 2014

Posts by Lauren


Total # Posts: 1,549

Chemistry
Answer check: Define a catalyst and explain a catalyst's role in a chemical reaction. A catalyst is a substance that speeds a chemical reaction without being permanently changed itself. It works by providing a convenient surface for the reaction to occur. The reacting ...
January 14, 2008

English
Hi, I need to know the background on the literay term: interjection. I have the definition and examples of it, but I can't seem to find any history on it. Help would be appreciated. Thank you so much!
December 16, 2007

Chemistry
Which if the following compounds is insoluble in water (NH4)2CO3 AgBr CuSO4 KI LiNO3 is it CuSO4 because sulfates are insolube
December 12, 2007

Chemistry
to lead nitrate because it is solube
December 12, 2007

Chemistry
a precipitate is expected when an aqueous solution of potassium iodide is added to an aqueous solution of: sodium sulfate iron(II) chloride calcium perchlorate barium hydroxide lead nitrate
December 12, 2007

Science
Explain Why A Hot Air Balloon Rises
December 12, 2007

Chemistry
Which if the following compounds is insoluble in water (NH4)2CO3 AgBr CuSO4 KI LiNO3 I thought it might be AgBr
December 11, 2007

Chemistry
When an aqueous solution of lithium chloride is mixed with an aqueous solution of ammonium sulfate a precipitate forms a new salt is formed a gas is evolved an acid and base are formed no reaction occurs I either thought it was a precipitate forms or no reaction occurs
December 11, 2007

Chemistry
All of the following are weak acids except HF H3PO4 H2SO4 HNO2 HC2H3O2
December 11, 2007

Chemistry
Which of the following is a weak base HOCl LiOH Ba(OH)2 KOH NH3
December 11, 2007

Chemistry
Which of the following indicates the exsistence of stron intermolecular forces of attraction in a liquid? a very low boiling point a very low vapor pressure a very low critical pressure a very low viscosity a very low heat of vaporization
December 11, 2007

Chemistry
Which of the following molecules has polar bonds and is nonpolar? HF ICI3 NF3 SF4 BF3
December 11, 2007

Chemistry
How do you make CIF2 into a Lewis Structure
December 5, 2007

Chemistry
Can you tell me if i did these right?? Lewis Dot Structure A. BrF = 5 dots around Br-F with 5 dots around it B. PBr3 = ? I dont know how to do because of the 3 C. NOF= 3 dots around N 2 dots around O and 5 dots around F N-O-F D. CO = 3 dots around C double bond between O and 4...
December 3, 2007

Chemistry
i dont know what the resonance description is so i dont have anything yet
December 3, 2007

Chemistry
write the resonance desription for the following A. ClNO2 B. NO-2
December 3, 2007

Chemistry
Decide which of the following bonds is least polar on the basis of electronegativities of atoms, H---S, Si---Cl, N---Cl.
November 30, 2007

Chemistry
nevermind i got it
November 30, 2007

Chemistry
Use Lewis Symbols to show the reaction of atoms to form arsine, AsH3. Indicate bonding pairs in the Lewis formula of AsH3 are bonding and which are lone pairs.
November 30, 2007

Math
How do I do a tree diagram to find the least common multiple
November 28, 2007

Chemistry
The principal quantum number of the valence electrons in an atom of lead is: A. 2 B. 3 C. 4 D. 5 E. 6
November 19, 2007

Chemistry
Which of the following elements has the smallest ionization energy? A. F B. Be C. B D. Mg E. C
November 19, 2007

Chemistry
How many valence electrons does phosphourous have
November 18, 2007

Chemistry
The maximum number of electrons that can be accomodated in a p subshell is A.2 B.4 C.6 D. 8 E. 10
November 18, 2007

Chemistry
The principal quantum number of the valence electrons in a atom of lead is A. 2 B. 3 C. 4 D. 5 E. 6
November 18, 2007

Chemistry
All of the following are true EXCEPT; A. the n=4 energy level has no f orbitals B. the 2p orbitals can have a maximum if 6 electrons C. the s orbital has a spherical shape D. there are 5 orbitals in a set E. the n=3 energy level has a set of d orbitals.
November 18, 2007

physics
6.4 m/s
November 11, 2007

Chemistry
so I did 1 divided by 4797297.498 and got 2.085 X 10^-7
November 4, 2007

Chemistry
so i got 1/4797297.498
November 4, 2007

Chemistry
okay so it should look like this 1/lambda= 1.0967758341 x 10^7(3^2)*[(1/3^2)-(1/4^2)] 1.0967758341 x 10^7(9)(.0486) i got 4798394.274
November 4, 2007

Chemistry
What is the wavelength of the transition from n=4 to n=3 for Li2+? In what region of the spectrum does this emission occur? Li2+ is a hydrogen-like ion. Such an ion has a nucleus of charge +Ze and a single electron outside this nucleus. The energy levels of the ion are -Z^2RH/...
November 4, 2007

Chemistry
Help needed for writing up a balance chemical equation for an acid/base titration: for an extended experimental experiment we tested the total acid content of orange juice, then had to write the balanced chemical equation for the experiment to do further calculations but i am ...
November 3, 2007

Chem
so am I solving for Rh This is what the equation should look like right: 1/9= Rh (1/2)-(1/3)
November 3, 2007

Chem
What is the wavelength of the transition from n=4 to n=3 for Li2+? In what region of the spectrum does this emission occur? Li2+ is a hydrogen-like ion. Such an ion has a nucleus of charge +Ze and a single electron outside this nucleus. The energy levels of the ion are -Z^2RH/...
November 3, 2007

Chemistry
What is the wavelength of the transition from n=4 to n=3 for Li2+? In what region of the spectrum does this emission occur? Li2+ is a hydrogen-like ion. Such an ion has a nucleus of charge +Ze and a single electron outside this nucleus. The energy levels of the ion are -Z^2RH/...
November 3, 2007

Chem
Thank you
November 3, 2007

Chem
well 9.98 X 10^11 / 3.00 x 10^8 = 3326.66
November 3, 2007

Chem
yes as you can see i put them in the answer i just dint type them out
November 3, 2007

Chem
9.98 X 10^11m = 3.00 X 10^8m/s (time) so I converted 998 million km into m now I divided 9.98/ 3.00 and got 3.33 x 10^19 is this correct
November 3, 2007

Chem
So rate is the speed of light too
November 3, 2007

Chem
The space probe Pioneer 11 was launched April 5,1973, and reached Jupiter in December 1974 traveling a distance of 998 million km. How long did it take an electromagnectic signal to travel to earth from Pioneer 11 when it was near Jupiter. The speed of light is, for all ...
November 3, 2007

Chemistry
so that website means that i need to use 1.6726 x 10^-27 kg why that number
November 3, 2007

Chemistry
What is the wavelength of a proton traveling at a speed of 6.21 km/s? What would be the region of the spectrum for electromagnetic radiation of this wavelength. For this one I did the same thing 6.63 X 10^-34/ (? kg)(6210 m/s) = How do get the kg for the problem
November 3, 2007

Chemistry
6.63 X 10^-34/ (2.66X 10^-26 kg)(521 m/s) = 1.30 X 10^-5 is this correct
November 3, 2007

Chemistry
so I dont need to go any father I just plug this back into the original problem and get my answer right
November 3, 2007

Chemistry
2.66 X 10 ^-23 (0.001 kg/1 g) = 2.66X 10^-26 that is what I want is kg
November 3, 2007

Chemistry
so that equals 2.66 grams/ 1 atom now where do I go from there
November 3, 2007

Chemistry
yes I know how big that is but I figured that you had 2 atoms of 6.02 x 10^23 so I divided by 2 to get the mass of 1 mol which is 3.01 X 10^23... why wouldnt you just take the 100 pm and make it into kg.
November 3, 2007

Chemistry
3.01 x 10^23 ???
November 3, 2007

Chemistry
sorry I copied the wrong problem it is supposed to be: 521 m/s not 6210 m/s 6.63 X 10^-34/ (? kg)(521 m/s) How do I get the kg for this problem
November 3, 2007

Chemistry
What is the de Broglie wavelength of an oxygen molecule, O2 traveling at 521 m/s? Is the wavelength much smaller or much larger than the diameter of an atom. (on the order of 100 pm) De Broglie wavelength = h/mv h = Planck's constant in J*s. m is mass in kg. v is velocity ...
November 3, 2007

Chemistry
The space probe Pioneer 11 was launched April 5,1973, and reached Jupiter in December 1974 traveling a distance of 998 million km. How long did it take an electromagnectic signal to travel to earth from Pioneer 11 when it was near Jupiter. Where do I begin???
November 1, 2007

Chemistry
What is the de Broglie wavelength of an oxygen molecule, O2 traveling at 521 m/s? Is the wavelength much smaller or much larger than the diameter of an atom. (on the order of 100 pm) How do I do this
November 1, 2007

Chemistry
What is the wavelength of a proton traveling at a speed of 6.21 km/s? What would be the region of the spectrum for electromagnetic radiation of this wavelength. How do I do this
November 1, 2007

Chem
How much heat is released when a mixture containing 10.0g CS2 and 10.0 g Cl2 reacts by the equation. CS2 + 3Cl2 ----> S2Cl2 + CCl4 Delta H = -230 kJ
November 1, 2007

Chemistry
A sample of natural gas is 80.0% CH4 and 20.0% C2H6 by mass. What is the heat from the combustion of 1.00 g of this mixture? Assume the products are CO2 and H2O. CH4 = -74.87 and C2H6 = -84.68
November 1, 2007

Chem
is 3.00 x 10^8 m/s the speed of light
November 1, 2007

Chem
distance is 998 million km what is veloctyoflight
November 1, 2007

Chem
The space probe Pioneer 11 was launched April 5,1973, and reached Jupiter in December 1974 traveling a distance of 998 million km. How long did it take an electromagnectic signal to travel to earth from Pioneer 11 when it was near Jupiter.
November 1, 2007

Chem
frequency = speed of light/656 nm how do you find the speed of light
November 1, 2007

Chem
Calculate the frequency associated with light of wavelength 656nm. (this corresponds to one of the wavelengths of light emitted by the hydrogen atom.)
November 1, 2007

Chem
Microwaves have frequencies in the range 10^9to 10^12/s (cycles per second) equivalent to between 1 gigahertz and 1 terahertz. What is the wave length of microwave radiation whose frequency is 1.258 X 10^10/s? How do I solve this problem
November 1, 2007

Chemistry
what do you mean by proportions???
November 1, 2007

Chemistry
How much heat is released when a mixture containing 10.0g CS2 and 10.0 g Cl2 reacts by the equation. CS2 + 3Cl2 ----> S2Cl2 + CCl4 Delta H = -230 kJ
November 1, 2007

Chemistry
so CH4 = -74.87 and C2H6 = -84.68 what do you mean by take 80% and 20%???
November 1, 2007

Chemistry
A sample of natural gas is 80.0% CH4 and 20.0% C2H6 by mass. What is the heat from the combustion of 1.00 g of this mixture? Assume the products are CO2 and H2O. How do I do this
November 1, 2007

Chemistry
sorry it is supposed to say When 23.6 of calcium chloirde CaCl2 was dissolved in water in a calorimeter, the temperature rose from 25.0 degrees C to 38.7 degrees C. If the heat capacity of the solution and the calorimeter is 1258 J/ degrees C, what is the enthalpy change when ...
November 1, 2007

Chemistry
When 23.6 of calcium chloirde CaCl2 was dissolved in water in a calorimeter, the temperature rose from 25.0 degrees C to 21.56 degrees C. If the heat capacity of the solution and the calorimeter is 1071 J/ degrees C, what is the enthalpy change when 1 mol of sodium nitrate ...
November 1, 2007

Chemistry
Ethanol, C2H5OH is mixed with gasoline and sold as gasohol. Use the following to calculate the grams of ehanol needed to provide 293 kJ of heat. C2H5OH + 3O2 ----> 2CO2 + 3H2O Delta H = -1235 kJ How do I do this question
November 1, 2007

Chemistry
Hydrogen H2 is used as a rocker fuel. The hydrogen is burned in oxygen to produce water vapor. 2H2 + O2 ----> 2H2O Delta H = -484 kJ What is the enthalpy change per gram of hydrogen?
October 30, 2007

Chemistry
With a platinum catalyst, ammonia will burn in oxygen to give nitric oxide, NO. 4NH3 + 5O2 -----> 4NO + 6H2O Delta H= -906 kJ What is the enthalpy change for the following reaction? NO + 3/2H2O ---> NH3 + 5/4O2
October 30, 2007

Chemistry
Hydrogen H2, is used asa rocker fuel. The hydrogen is burned in oxygen to produce water vapor. 2H2 + O2 ----> 2H2O Delta H= -484 kJ What is the enthalpy change per gram of hydrogen.
October 29, 2007

Chemistry
Hydrogen sulfide, H2S is a foul smelling gas. It burns to form sulfur dioxide. 2H2S +3O2 ----> 2N2 +6H2O Delta H=-1036kJ Calculate the enthalpy change to burn 26.7 g of hydrogen sulfide.
October 29, 2007

Chemistry
with a platinum catalyst, ammonia will burn in oxygen to gove nitric oxide NO. What is the enthalpy change for the following reaction? NO + 3/2 H2O -----> NH3 + 5/4 O2
October 29, 2007

Chemistry
235 grains (0.0648 g/ 1 grain)(1000 kg/1 g)= 2.52 X 10^3 ft/s (1 m/3.28 feet)= is this the correct set up then where do i go from here
October 29, 2007

Chemistry
A bullet weighing 235 grains is moving at a speed of 2.52 X 10^3 ft/s. Calculate the kinetcic energy of the bullet in joules ahd in calories. One grain equals 0.0648 g. Can someone help me out on this please K. E.= 1/2 mv2 . Convert m to kg Convert ft/sec to meters/second. ...
October 29, 2007

Chemistry
A bullet weighing 235 grains is moving at a speed of 2.52 X 10^3 ft/s. Calculate the kinetcic energy of the bullet in joules ahd in calories. One grain equals 0.0648 g. Can someone help me out on this please
October 28, 2007

Chemistry
-281.0 kJ ( 1 Joules/ 1000 kJ)(1 calorie/ 4.184 Joules)(1 k cal/ 1000 calories) is this the correct set up
October 28, 2007

Chemistry
Hydrogen sulfide H2S is produced during decomposition of organic matter. when .5000 mol H2S burns to produce SO2 and H2O. -281.0 kJ of heat is released. what is this heat in kilocalories. Can you help me start this please
October 28, 2007

Chemistry
3.97m
October 25, 2007

Chemistry
what volume of water must be added to 10ml og 6.0M NaOH to make a solution that is .30 M in NaOH How do I solve for this
October 25, 2007

Chemistry
Chloroform CHCl3, is a volatile liquid solvent. Caculate the density of cholroform vapor at 98 degrees C and 797 mmHg. Give the answer in grams per liter. How do I start this out
October 23, 2007

Chemistry
What is the conversion for kPa to atm What is the conversion for dm^3 to L
October 23, 2007

Chemistry
Magnesium burns in air to produce magnesium oxide MgO and magnesium nitride Mg3N2. Magnesium nitride reacts with water to give ammonia. What volume of ammonia gas at 24 degrees C and 753 mmHg will be produced from 4.56 g of magnesium nitride. P= 753 mmHg (1 atm/ 760mmHg)= .991...
October 23, 2007

Chemistry
An aqueous solution of ammonium nitrate NH4NO2 decomposeds when heated to give off nitrogen. This reaction may be used to prepare pure nitrogen. How many grams of ammonium nitrite must have reacted if 3.75dm^3 of nitrogen gas was collected over water at 26 degrees C and 97.8 ...
October 23, 2007

Chemistry
Calculate the total pressure (in atm) of a mixture of 0.0300 mol of helium, He and 0.0200 mol of oxygen O2 in a 4.00 L flask at 20 degrees C. Assume the ideal gas behavior. Can someone help me start this out... Please
October 23, 2007

Chemistry
Magnesium metal reacts with hydrochloric acid to produce hydrogen gas H2 Mg + 2HCl ----> MgCl + H2 Calculate the volume (in liters) of hydrogen produced at 33 degrees C and 665 mmHg from 0.0840 mol Mg and excess HCl P= .875 atm V= ? n= .0840 mol R= 0.0821 T= 306 K V= nRT/ P...
October 23, 2007

Chemistry
Nitric Acid is produced from nitric oxide, NO which in turn is prepared from ammonia by the ostwald process. 4NH3 + 5O2 -----> 4NO + 6H2O What volume of oxygen at 35 degrees C and 2.15 atm is neeeded to produce 50.0 g of nitric oxide T= 273+35 = 308 K P = 2.15 atm n= 50.0 g...
October 23, 2007

Chemistry
Okay I see where I went wrong
October 23, 2007

Chemistry
A 2.50 L flask was used to collect a 5.65 g sample of propane gas, C3H8. After the sample was collected, the gas pressure was found to be 741 mmHg. What was the temperature of the propane in the flask. P= 741 mmHg(1 atm/760 mmHg)= .975 atm V= 2.50 L n= 5.65 g C3H8 (1 mol/44 g...
October 23, 2007

Chemistry
.985(V)=.177(.0821)(296)= Same thing do you multiply and then divide by .985
October 23, 2007

Chemistry
According to your calculations a reaction should yield 5.67 g of oxygen O2. What do you expect the volume to be at 23 degrees C and 0.985 atm? I got the all the amounts 5.67 g 23 degrees C = 296 K .985 atm And use the ideal gas law Can you help me out by starting it again
October 23, 2007

Chemistry
P(5.00L)= .446 mol(.0821)(292K) It would look like this right then do I just multiply it all together and divide by the 5.00 L
October 23, 2007

Chemistry
In an experiment, you fill a heavy walled 5.00 L flask with methane gas, CH4. If the flask contains 7.13g of methane at 19 degrees C, what is the gas pressure. Use the ideal gas law. Can some one help me get started on this problem please
October 23, 2007

Chemistry
Thanks for all the help DrBob I really appreciate it
October 23, 2007

Chemistry
Sorry it should be 8.58 * 1.020/ 1.584= Answer: 5.525 m^3 Is that right now
October 23, 2007

Chemistry
A driving bell is a container open at the bottom. As the bell descends, the water level inside changes so that the pressure inside equals the pressure outside. Intially the volume of air is 8.58m^3 at 1.020 atm and 20 degrees C. What is the volume at 1.584 atm and 20 degrees C...
October 23, 2007

Chemistry
An experiment called for 4.83 L of sulfur dioxide at 0 degrees C and 1.00 atm. What would be the volume of this gas at 25 degrees C and 1.00 atm? V1= 4.83 L V2= ? T1= 273 K T2= 298 K 1 atm P1 and P2 V2 = V1 * T2/T1 4.83 L * 298 K /273 K = ANSWER: 5.27 L Is this correct.
October 22, 2007

Chemistry
A mole of gas at 0 degrees C and 760 mmHg occupies 22.41 L. What is the at 20 degrees C and 760 mmHg? T1= 273 K T2= 293 K V1= 22.41 L V2= ? 22.41 L * 293 K/ 273 K = ANSWER: 24.05 L Is this the correct answer
October 22, 2007

Chemistry
Is this right??
October 22, 2007

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