Friday

January 20, 2017
Total # Posts: 3,295

**chem**

A certain first-order reaction has a rate constant of 2.75 10-2 s−1 at 20.°C. What is the value of k at 50.°C if Ea = 75.5 kJ/mol? i know to use the ln(k1/k2)= (ea/R)((1/T1)-(1/T2)) but how do i know what T2 is when i only have one temp? there is a b part to the ...

*February 10, 2013*

**science**

I figured that one out but can smoneoe help me with this one. The activation energy of a certain reaction is 65.7 kJ/mol. How many times faster will the reaction occur at 51°C than at 8°C?

*February 9, 2013*

**science**

Calculate the fraction of atoms in a sample of argon gas at 365 K that has an energy of 11.0 kJ or greater.

*February 9, 2013*

**Physics, help!!**

How do I get the equation T=2pi(sqrt(m/k)) to the linear equation y=mx+b?

*February 4, 2013*

**chem**

torr

*February 2, 2013*

**chem**

does the temperature it gives have anything to do with the problem?

*February 2, 2013*

**chem**

i just tried that and it is wrong.

*February 2, 2013*

**chem**

is k negative because of the s-1? without making it negative i got 15.21 which seemed more reasonable but when i plugged it in it was wrong

*February 2, 2013*

**chem**

i got 11873 which seems kinda high..?

*February 2, 2013*

**chem**

The decomposition of sulfuryl chloride (SO2Cl2) is a first-order process. The rate constant for the decomposition at 660 K is 4.5 10-2 s-1. (a) If we begin with an initial SO2Cl2 pressure of 425 torr, what is the pressure of this substance after 74 s? what is the equation to ...

*February 2, 2013*

**science**

sorry this was the info given Molecular iodine, I2(g), dissociates into iodine atoms at 625 K with a first-order rate constant of 0.271 s−1.

*January 31, 2013*

**science**

If you start with 0.054 M I2 at this temperature, how much will remain after 5.42 s assuming that the iodine atoms do not recombine to form I2?

*January 31, 2013*

**Physics**

How much energy is released when 1 gram of steam condenses to water at 100 degrees Celsius?

*January 31, 2013*

**Physics**

what is the number of grams of steam at 100 degrees C that will condense as 5g of ice at 0 degrees C melts?

*January 31, 2013*

**physics**

if 8100 calories are released from 200g of steam at 100C, how much of the steam condenses?

*January 31, 2013*

**chemistry**

i don't know how to do any of it

*January 30, 2013*

**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 .0250 1.13 X ...

*January 30, 2013*

**algebra**

Jet #1 leaves an airport at 600 km/h. Jet #2 leaves 3/4 hour after jet #1 in same direction. How long until jet #2 overtakes jet #1

*January 28, 2013*

**Spanish help please.**

Acabar de means "to have just." So, acabo de estudiar means "I just studied." You conjugate "acabar," but NOT the verb that follows "de." You always follow a preposition (like de) with a verb that is NOT conjugated (a verb that ends in -...

*January 28, 2013*

**science**

Using data from this table of molal boiling-point-elevation and freezing-point-depression constants, calculate the freezing and boiling points of each of the following solutions. a)0.39 m glucose in ethanol (b) 22.8 g of decane, C10H22, in 53.9 g CHCl3 (c) 3.90 g NaOH in 109 g...

*January 23, 2013*

**Chemistry**

I did that. doesnt it have to be liters of the total solution? so how do we factor in the asprin into the liters?

*January 22, 2013*

**Chemistry**

What is the osmotic pressure formed by dissolving 50.8 mg of aspirin (C9H8O4) in 0.200 L of water at 18°C?

*January 22, 2013*

**math**

10+2n=8n-8(+8)

*January 22, 2013*

**astronomy**

36,000000

*January 16, 2013*

**Physics**

For the problem (8.99 X 10^9 NM^2/c^2)(1 X 10^-6c) / (.1m)^2 = .90 N When I put this in my calculator I did not get .90N. Am I suppose to convert the units to get the answer. Thank you for your help.

*January 11, 2013*

**5th grade math**

and how do i do that please

*January 8, 2013*

**5th grade math**

I am sorry, can u show your division please. when i divide 87 for 60 i get 1.45. Please help!

*January 8, 2013*

**5th grade math**

Hello Ms. Sue, How did you get 15 27/60 please? Thanks, Hannah

*January 8, 2013*

**5th grade math**

please help solved the following fraction 11 13/15 + 3 7/12 = 14 3/4 + 7 + 5 7/8 = Thanks, Hannah

*January 8, 2013*

**science**

how did the invention of the microscope help doctors to understand what caused diseases.

*January 8, 2013*

**math**

I don't know how to change 1/3 and 2 1/3 into a decimal and still show my work

*December 19, 2012*

**Physics**

A plane is heading south with a velocity of 150 kilometers/hour. It experiences a tailwind with a velocity of 20 kilometers/hour. Find the resultant velocity of the plane

*December 17, 2012*

**environmental science**

why are cultivation practices for pest control not widely used today?

*December 16, 2012*

**physics**

Sorry, i have no idea!!! I have a physics final tomorrow!!! Freaking out!!!!

*December 13, 2012*

**algebra**

a parking meter gives 30 minutes for each quarter and 6 minutes for each nickel. the equation 30x+6y=60 describes the number of quarters x and nickels y that you need to park for 60 minutes what does the x-intercept represent?

*December 12, 2012*

**social studies**

britain passed the stamp act

*December 4, 2012*

**science**

fertilization is the union of sperm cell and egg cell

*December 1, 2012*

**science**

what is the meaning of fertilization?

*December 1, 2012*

**math**

about 7x10 to the power of 3 babies are born each day in the city. about how many babies are born each day in the city?.give the abswer un standard form

*December 1, 2012*

**math**

if 3 bananas cost £1.14 how much will 5 of them cost? and how do you work it out?

*November 23, 2012*

**math**

if 3 bananas cost £1.14 how much will 5 of them cost? and how do ypu work it out?

*November 23, 2012*

**math**

if 3 bananas cost £1.14 how much will 5 of them cost? and how do ypu work it out?

*November 23, 2012*

**math**

if 3 bananas cost £1.14 how much will 5 of them cost? and how do ypu work it out?

*November 23, 2012*

**Chemistry**

What is the concentration in mol/L of a CuSO4 solution containg 1.0 mole of CuSO4 in 250 mL of Solution? I would like to know how to calculate the answer and be giving the correct answer please.

*November 19, 2012*

**physics**

A projectile is launched off of a 18.6 m high cliff with a velocity of 12.8 m/s. If the projectile is launched at an angle of 20° above the horizontal, how far did it travel horizontal before it hit the ground below?

*November 15, 2012*

**english**

also i have my introduction written and i need someone to check it over (its in outline form now) A. “I will instruct you and teach you in the way you should go; I will counsel you and watch over you.” Psalm 32:8 B. As the main character in Daniel Defoe’s book, ...

*November 15, 2012*

**english**

i am writing a literary research paper on the book robinson crusoe. my thesis is In "Robinson Crusoe" Daniel Defoe uses the protagonist to show the sporadic but guiding relationship between God and man. I am having trouble coming up with a title. So far I have "...

*November 15, 2012*

**Scoial Studies**

As a general rule, homeowners should carry property damage insurance on their structures amounting to at least ____ percent of their value (the cost of rebuilding them). A. 50 B. 60 C. 70 D. 80

*November 15, 2012*

**chemistry**

a chemist puts 6 moles of nitrogen gas and 7 moles hydrogen gas into an evacuated 1 liter container. The system reaches equilibrium at a certain temperature according to the process outlined above. when the system is at equilibrium the chemist determines the ammonia ...

*November 14, 2012*

**math**

Can't remember the way to solve for the variable. 5x + 6 = 7x. Answer is 3, but how to do other problems?

*November 11, 2012*

**algebra**

-13=5(1+4m)-2m

*November 11, 2012*

**chemistry**

If a saline solution has a concentration of 0.25 g per mL, calculate the following. a) The concentration of this solution in %w/v. b) The concentration of this solution in grams per litre (g/L). c) The concentration of this solution in milligrams per mL (mg/mL).

*November 7, 2012*

**please check my answer**

Consider the following equations. N2H4(l) + O2(g) N2(g) + 2 H2O(l) ÄH = -622.2 kJ H2(g) + 1/2 O2(g) H2O(l) ÄH = -258.5 kJ H2(g) + O2(g) H2O2(l) ÄH = -187.8 kJ Use this information to calculate the enthalpy change for the reaction shown below. N2H4(l) + 2 H2O2(l...

*November 6, 2012*

**Math Algr.2**

Convert to standard form (AX+BY=C) 1.y=3/2x+6 2. 2/3y=2x-5 3.7y-21=1/2x 4.-2/3x+3/4y=1 Convert to Slope/intercept form (y=mx+b) 1.3x-27=14 2.-9y-6x-18=0 3.8-2x+4y=0 12x=4y-8 I need help going through this because I am not sure if I am doing everything right and I also don'...

*November 6, 2012*

**chem- i reallyneed help**

oops that's me ^

*November 6, 2012*

**chem- i reallyneed help**

Consider the following equations. N2H4(l) + O2(g) N2(g) + 2 H2O(l) ÄH = -622.2 kJ H2(g) + 1/2 O2(g) H2O(l) ÄH = -258.5 kJ H2(g) + O2(g) H2O2(l) ÄH = -187.8 kJ Use this information to calculate the enthalpy change for the reaction shown below. N2H4(l) + 2 H2O2(l...

*November 6, 2012*

**chem urgent!**

Set up a Hess's law cycle, and use the following information to calculate ÄH°f for aqueous nitric acid, HNO3(aq). You will need to use fractional coefficients for some equations. 3 NO2(g) + H2O(l) 2 HNO3(aq) + NO(g) ÄH° = -138.4 kJ 2 NO(g) + O2(g) 2 NO2(g...

*November 6, 2012*

**chem**

(a) When a 4.75-g sample of solid ammonium nitrate dissolves in 60.0 g of water in a coffee-cup calorimeter (see figure), the temperature drops from 23.0‹C to 16.6‹C. Calculate ƒ¢H (in kJ/mol NH4NO3) for the solution process NH4NO3(s) ¨...

*November 6, 2012*

**Algr1**

Find the x and y intercept of the equations. 1.5x+6y=-30 2.x-4y=-16 3.-3x+4y=12 How would I solve these and what is the anwsers

*November 5, 2012*

**Algr1**

Find the x and y intercept of the equations. 1.5x+6y=-30 2.x-4y=-16 3.-3x+4y=12 How would I solve these and what is the anwsers

*November 5, 2012*

**Algr.1**

Find the x and y intercept of the equations. 1.5x+6y=-30 2.x-4y=-16 3.-3x+4y=12 How would I solve these and what is the anwsers

*November 5, 2012*

**Chemistry(Please check)**

Thank you!

*November 3, 2012*

**Chemistry(Please check)**

For an experiment on specific heat capacities my data for measured specifi heats was consistently higher than the accepted values. I am not sure why this is. Would it be because my initial temperature that I started the experiment with was higher than it should have been? ...

*November 3, 2012*

**Chemistry(Please, please help)**

I am trying to draw a constitutional isomer for the compound CH3CH=CHCH3 but I am having some trouble. H-C-C=C-C-H I drew the first compound like this with more hydrogens on the Cs. How could I draw another strucutre?

*November 1, 2012*

**Math(Please check)**

Please diregard, I figured out my mistake.

*November 1, 2012*

**Math(Please check)**

For an experiment on specific heat capacities of metal in physics, I am trying to calculate my percent error but am having some trouble. After collecting my experimental data for c (cal/g) for the object that was used which was aluminum my results are: trial 1 = .19 trial 2...

*November 1, 2012*

**Math/Physics(Please check work)**

Please disregard. I figured out my mistake.

*November 1, 2012*

**Math/Physics(Please check work)**

For an experiment on specific heat capacities of metal in physics, I am trying to calculate my percent error but am having some trouble. After collecting my experimental data for c (cal/g) for the object that was used which was aluminum my results are: trial 1 = .19 trial 2...

*November 1, 2012*

**math**

964

*October 31, 2012*

**please help**

When is the best time to read review or discussion questions? A. Immediately after you have finished all of the reading. B. After you write your notes. C. Before you begin any detailed reading. D. Throughout your detailed reading.

*October 30, 2012*

**Chemistry(Please help)**

ok thank you and for the specific rotation of L-erythrose 4-phosphate would it be the same as for D-erythrose 4-phosphate which I determined was 50 or would it be -50?

*October 28, 2012*

**Chemistry(Please help)**

The path of length was given in cm so I converted it to dm but I am not sure if I calculated the concentration correctly. A 50 gram sample was dissolved in 10 mL solution so would I do 50/10?

*October 28, 2012*

**Chemistry(Please help)**

Oh ok, the question asks me to find the specific rotation for D-erythrose 4-phosphate which I determined was 50 and then it asks me to find the specific optical rotation for L-erythrose 4-phosphate so I thought that it would be a different formula.

*October 28, 2012*

**Chemistry(Please help)**

I know that to calculate the specific rotation for a compound you do observed rotation / path length(dm) * conc. (g/ml). I am confused about how to calculate the specific optical rotation for a compound. Thank you for your help!

*October 28, 2012*

**Chemistry(Please check)**

Determine if the equation is SN1, SN2,E2 or E1. CH3CH2O- + CH3CH2BR = CH3CH2OCH2CH3 + BR- I think that this is SN2. Would you agree?

*October 25, 2012*

**math**

20 Minivans

*October 24, 2012*

**Algebra 1**

A 30-pack of blank CDs cost $9.50. A 50-pack of CDs cost $13. How can you tell which is the better buy?

*October 21, 2012*

**Trigonometry**

The average temperature, in °F, for Atlanta, GA is modeled by the sinusoidal function y = 18.25 sin(pi/6 t - 2.09) + 61.15 where t is the time in months and January is t=1. What is the average Temperature for the month of February? Using the same equation, what is the ...

*October 20, 2012*

**Chemistry(Please answer)**

How many chirality centers does the compound 1,3-dibromo-2,4-dichloro-5-fluorocyclopentane have? This compound has three different elements, a Br which is repeated twice, a cl which is also repeatd twice, and a fluorine. I was thinking that the number of centers would be 3 ...

*October 18, 2012*

**Math**

850 hectare = ? km^2 850 ha (1 km/100 ha) = 8.5km^2 Is this conversions correct? not just the answer but also how I got to the answer. PLEASE let me know if im on the right track, thanks!

*October 17, 2012*

**Math**

Change 300 mm3(cubed) to cm3(cubed). I have no idea how to work this out. Any help you can give me would be greatly appreciated!! Thanks

*October 15, 2012*

**Chemistry(Urgent, please check)**

For C4H10O a constitutional isomer can be written as C-C-C-C-O-H with hydrogens also coming off of the 4 carbons. I know that this is an alcohol. I need to know if there are stereoisomers for this other than conformers. I think that there are stereoisomers because you can just...

*October 11, 2012*

**Chemistry(Please check, thanks)**

For C4H10O a constitutional isomer can be written as C-C-C-C-O-H with hydrogens also coming off of the 4 carbons. I know that this is an alcohol. I need to know if there are stereoisomers for this other than conformers. I think that there are stereoisomers because you can just...

*October 11, 2012*

**math**

There were 12 boys and 18 girls in a class. Then, 3 more boys joined the class and 2 girls left. What is the ratio of the number of boys to the number of girls in the class now?

*October 8, 2012*

**Econ**

what is the purpose of the labor law- executive order- created in 1965

*October 8, 2012*

**Math**

For an experiement to test elastic collision, ball 2 was at rest and ball 1 was released from a certain height and distance and hit ball 2. A set of measurements were collected which was v1 and v2 prime for each ball. I need to calculate the kinetic energy before and after ...

*October 6, 2012*

**Math(Please help, thank you)**

Im alittle confused because my data sheet gives values for mass, height, diameter and then v1 and v'2. So would v1 ball one and V'2 ball two?

*October 5, 2012*

**Math(Please help, thank you)**

For an experiement to test elastic collision, ball 2 was at rest and ball 1 was released from a certain height and distance and hit ball 2. A set of measurements were collected which was v1 and v2 prime for each ball. I need to calculate the kinetic energy before and after ...

*October 5, 2012*

**Chemistry(Please help)**

thank you

*October 4, 2012*

**Chemistry(Please help)**

I am trying to figure out what functional group the compound CH2ClCH3 is in. I know that it is not a ketone, alcohol, ester, ether, amine, amide, ect..I do not know what it could be.

*October 4, 2012*

**Chemistry(Please check)**

identify the functional group and indicate polar bonds by assigning partial positive and negative charges. 1) The structure CH3OCH3 is drawn out and I know that this is an ether because the O is bonded to two carbons but I am not sure how to assign the charges. I think that ...

*October 4, 2012*

**Chemistry**

I am trying to figure out what functional group the compound CH2ClCH3 is in. I know that it is not a ketone, alcohol, ester, ether, amine, amide, ect..

*October 4, 2012*

**Chemistry**

identify the functional group and indicate polar bonds by assigning partial positive and negative charges. 1) The structure CH3OCH3 is drawn out and I know that this is an ether because the O is bonded to two carbons but I am not sure how to assign the charges. I think that ...

*October 4, 2012*

**Physical science.**

A skydiver who jumps out of a plane that has a forward velocity of 40 m/s. That means that the skydiver has a forward velocity of 40m/s. Ignore the air resistance. The questions: What difference is there between the downward velocities of the skydiver who jumped out of the ...

*September 28, 2012*

**Chemistry(Please answer, thanks)**

So then they are not conformers or constitutional isomers correct?

*September 27, 2012*

**Chemistry(Please answer, thanks)**

I have to answer the following questions about C3H7Cl: Are there different constitutional isomers for this formula, are there different cis/trans isomer, and are there different conformers? I know that C3H7Cl can be drawn two ways: H-C-C-C-Cl With H's above and below the ...

*September 27, 2012*

**Chemistry**

I have to answer the following questions about C3H7Cl: Are there different constitutional isomers for this formula, are there different cis/trans isomer, and are there different conformers? I know that C3H7Cl can be drawn two ways: H-C-C-C-Cl With H's above and below the 3...

*September 27, 2012*

**Science**

Which of these statements concerning the interaction of light waves with the glass of a greenhouse is correct? A. Infrared is transmitted through the glass and is changed to heat B. The glass reflects ultraviolet waves C. Visible light is transmitted through the glass Or D. ...

*September 26, 2012*

**career**

your link just brought up the main google page

*September 25, 2012*