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November 24, 2014

Posts by hannah


Total # Posts: 2,904

chemistry(Please check)
1)Which thermochemical equation and data does not agree with the other two written? a) 2NO (g)+ O2 (g) ->2 NO2 (g) deltaH=-169.8 b) NO (g) + 1/2 O2 (g) -> NO2 (g) delta H = -56.6 c) 4 NO2 (g) -> 4 NO (g) + 2 O2 (g) delta H = +226.4 d)all three equations are in ...
January 20, 2012

Chemistry
ok so the lowest mass is Xe and the highest mass is NO2.
January 18, 2012

Chemistry
Is K the temp in kelvins? So for an example He would be 373K(sqrt 1/4.0026) = 186.43 Did I do that right?
January 18, 2012

Chemistry
Which molecule below has the greatest average velocity at 100 degrees celsius? He, Cl2, Xe, O2, NO2 I know that I already posted this the other day and the response I was given was to use the root mean squared equation. I know that the molecule with the smallest mm will be the...
January 18, 2012

chemistry
What is the molarity if 750. mL of a solution containing 332.5g of copper (II) sulfate
January 18, 2012

Chemistry
Ok thank you
January 16, 2012

Chemistry
Exactly 5.02 grams of an unknown gas was sealed in a 3.0L flask at 37 degrees celsius and a pressure of 1.25 atm. Which on of the following is most likely to be the unknown? H2O, HBr, HCN, H2S, C2H2 ok so I did (1.25)(3.0) = n(0.0821)(310) 3.75 = n(25.451) n=0.1473 Then I did ...
January 16, 2012

Chemistry
ok so I did (1.25)(3.0) = n(0.0821)(310) 3.75 = n(25.451) n=0.1473 Then I did 0.1473= 5.02/mm but I am not sure if this is right.
January 15, 2012

Chemistry
Exactly 5.02 grams of an unknown gas was sealed in a 3.0L flask at 37 degrees celsius and a pressure of 1.25 atm. Which on of the following is most likely to be the unknown? I am not sure how to start this.
January 15, 2012

Chemistry
oh ok because the answer of 0.258 threw me off but I understand why thats not the answer.
January 15, 2012

Chemistry
Ok so the answer has to be in mm Hg since the total pressure was in mm Hg correct?
January 15, 2012

Chemistry
Nevermind I didnt realize 1380 was stated in the problem, but I still not sure which answer choice to choose.
January 15, 2012

Chemistry
Ok and how did you get 1380? When I did 0.258*1380 I got 356.04. The answer choices that they gave me are 0.258atm, 300mm Hg, 360 mm Hg, 5300mm Hg, and 8000 mm Hg.
January 15, 2012

Chemistry
ok so for Ar i got 1.49. Then I added 1.27+1.49+3.04 = 5.8 and then I did 1.49 / 5.8 = 0.256. Now do I have to multiply 0.256 by the total?
January 15, 2012

Chemistry
A mixture of three gases has a total pressure of 1380 mm Hg at 25 degrees celsius. If the mixture contained 56 grams CO2, 3.04 mol CO and 9.03 X 10^23 atoms of Argon, the partial pressure of argon would be about? ok so first I did 56 CO2 X 1/44.01 = 1.27 then 3.04 CO X 1/28....
January 15, 2012

Chemistry
Ok I understand thank you!
January 15, 2012

Chemistry
I got 467460 = p2(683.85) then i divided 683.85 by 467460 and got 683.57. Th answer choices that were given are 110 mm Hg, 680mm Hg, 260 mm Hg, 280 mm Hg, and 1560 mm Hg so the closest to my answer is 680. Does that sound correct?
January 15, 2012

Chemistry
A sample of chlorine gas at a pressure of 420 mm Hg and in a volume of 3.50L was heated from 18.0 degrees celsius to 45 degrees celsius after being transferred to a container of volume 2.35L. The pressure in this new container should be about? The original T is 18 degrees ...
January 15, 2012

Chemistry
Ok thank you!!
January 15, 2012

Chemistry
Maybe, so in that case I would just have to plug everything into the van der waals equation to find the answer?
January 15, 2012

Chemistry
My teacher is going to list the molar masses of five gases and ask us which has the largest molar volume at STP. How would I go about solving this? Would the smallest number have the largest volume?
January 15, 2012

Chemistry
ok so first I did 56 CO2 X 1/44.01 = 1.27 then 3.04 CO X 1/28.01 = 0.108 then 9.03e23 Ar X 1/39.95 = 2.26e22 but im not sure I did this right. Is this correct so far before I continue? Thank you for your help.
January 14, 2012

Chemistry
A mixture of three gases has a total pressure of 1380 mm Hg at 25 degrees celsius. If the mixture contained 56 grams CO2, 3.04 mol CO and 9.03 X 10^23 atoms of Argon, the partial pressure of argon would be about? First I did 9.03e23 * 760/1 = 2.26e22 and then I was going to do...
January 14, 2012

Chemistry
According to the ideal gas law a 9.03 sample of oxygen gas in a 0.8112 container at 499k should exert a pressure of 456atm. By what % does the pressure calculated using van der waals equation differ from the ideal pressure? For O2 gas a=1.36 L^2atm/mol2 and b=3.18e-2 Hint: %...
January 14, 2012

chemistry
My teacher is going to list the molar masses of five gases and ask us which has the largest molar volume at STP. How would I go about solving this?
January 14, 2012

Chemistry
Yes the original T is 18 degrees celsius so would it be 420*3.50 / 291 K = p2 * 2.35 / 318 5.05 = p2 * 2.35 / 318. I am just not sure how to solve for the right side of the equation to find p2.
January 14, 2012

Chemistry
A sample of chlorine gas at a pressure of 420 mm Hg and in a volume of 3.50L was heated from 18.0 degrees celsius to 45 degrees celsius after being transferred to a container of volume 2.35L. The pressure in this new container should be about? Would I use (p1)(v1) = (p2)(v2) ...
January 14, 2012

Chemistry
so I just have to compare the molar mass of each gas and the smallest is the greatest?
January 13, 2012

Chemistry
What is RT? So for He I would do square root 3 times (value of RT) / 1.0079 correct?
January 13, 2012

Chemistry
Which molecule has the greatest average velocity at 100 degrees celsius. He, Cl2, Xe, O2, NO2 I used the root mean squared formula but I think I did it wrong. I got Xe as my answer. Is this correct?
January 13, 2012

Chemistry
ok thank you
January 13, 2012

Chemistry
Well the answer choices were 18L, 8.0L, 12.8L, 15L and 11.3L and when i divided 12 by 0.9399 which I got from 313/333 I got 12.76.
January 13, 2012

Chemistry
I tried again and got 12.8
January 13, 2012

Chemistry
I got 11.3 L as my answer. Is this correct?
January 13, 2012

Chemistry
So would I set it up as 12.0L / v2 = 313 K / 333K ?
January 13, 2012

Chemistry
A 12.0L sample of a as at a constant pressure of 608 mm Hg was heated from 40 degrees celsius to 60 degrees celsius. What volume does the gas now occupy? would I multiply 608 by 12 and then divide by the degrees celsius?
January 13, 2012

Chemistry
O ok thank you!!
January 13, 2012

Chemistry
What compound forms when one molecule of HCl and one molecule of NH3 combine? It is an ionic compound. I am not sure how to find this out. I thought is was H3O but that is not right.
January 13, 2012

Chemistry
Which molecule below has the greatest average velocity at 100 degrees celsius? He, Cl2, Xe, O2, NO2 I am not sure how to find this out. Thank you for your help!
January 12, 2012

Chemistry
I got 2.98g/L. Is this correct?
January 11, 2012

Chemistry
Calculate the density of sulfur trioxide gas at 35 degrees celsius and 715 torr pressure. I know that d=m/v = PM/RT. Im not sure how to set this up. I know the molar mass of sulfur trioxide is 80.0642 but im not sure if I need to use that.
January 11, 2012

Chemistry(Please check)
1) Which statement below is incorrect if any? a)when gas is at STP, the pressure of the gas is at 1.00 atm. b)when a gas is at STP, the temperature of the gas is 25 degrees celsius c)at STP the molar volume of a gas is 22.4L d)at STP the molar volume of all gases are the same ...
January 11, 2012

Chemistry(Please check)
1) choose the correct statement about the postulates of kinetic theory of gases. a) a sample of a gas consists of a small number of large particles close together. b) the movement of gas molecules is predictable, not random. c) when gas molecules collide, they permanently ...
January 10, 2012

Algabra A(1)
a solution of 67% soution is mixed with a solution o f57% to make 30 liters of a 59% solution. How many of each solution is used?
January 3, 2012

algebra
i need help
January 2, 2012

Physics
The angular speed of a propeller on a boat increases with constant acceleration from 12 rad/s to 26 rad/s in 2.5 revolutions. What is the acceleration of the propeller?
December 17, 2011

physics13
Find the mass of each of these weights in kg (a) 97 N (b) 83 N (c) 1.03 N
December 11, 2011

physics12
The instruments attached to a weather balloon have a mass of 5.1 kg. (a) The balloon is released and exerts an upward force of 102 N on the instruments. What is the acceleration of the balloon and instruments? (b) After the balloon has accelerated for 13 seconds, the ...
December 11, 2011

physics10
A sled of mass 51 kg is pulled along snow-covered, flat ground. The static friction coefficient is 0.30, and the sliding friction coefficient is 0.10. (a) What does the sled weigh? (b) What force will be needed to start the sled moving? (c) What force is needed to keep the ...
December 11, 2011

physics9
You are driving a 2460.0-kg car at a constant speed of 19.0 m/s along an icy, but straight and level road. While approaching a traffic light, it turns red. You slam on the brakes, Your wheels lock, the tires begin skidding, and the car slides to a halt in a distance of 27.0 m...
December 11, 2011

physics8
Your new motorcycle weighs 2411 N. What is its mass in kilograms?
December 11, 2011

physics7
A 81.0-kg (179 lb) boxer has his first match in the Canal Zone (g = 9.782 m/s2) and his second match at the North Pole (g = 9.832 m/s2). (a) What is his mass in the Canal Zone? (b) What is his weight in the Canal Zone? (c) What is his mass at the North Pole? (d) What is his ...
December 11, 2011

physics6
A 64-kg boy and a 42-kg girl use an elastic rope while engaged in a tug-of-war on an icy frictionless surface. If the acceleration of the girl toward the boy is 3.5 m/s2, determine the magnitude of the acceleration of the boy toward the girl.
December 11, 2011

physics5
A race car has a mass of 707 kg. It starts from rest and travels 40 m in 4.0 s. The car is uniformly accelerated during the entire time. What net force is applied to it?
December 11, 2011

physics4
After a day of testing race cars, you decide to take your own 1540-kg car onto the test track. While moving down the track at 12 m/s, you suddenly accelerate to 27 m/s in 9 s. What is the average net force that you have applied to the car during the 9-s interval?
December 11, 2011

physics3
when a karate strike hits wooden blocks, the hand undergoes an acceleration of -6500 m/s2. Medical data indicates the mass of the forearm and hand to be about 0.7 kg. What is the force exerted on the hand by the blocks?
December 11, 2011

physics2
A 873 kg (1930 lb) dragster completed the 402.0 m (0.2498 mile) run in 4.950 s. If the car has constant acceleration, what would be its acceleration and final velocity?
December 11, 2011

physics
A 880-kg (1945 lb) dragster, starting from rest, attains a speed of 27.3 m/s (61.0 mph) in 0.60 s. (a) Find the average acceleration of the dragster during this time interval? (b) What is the size of the average force on the dragster during this time interval? (c) Assume the ...
December 11, 2011

us history
what do you think were the 15 most important events in us history between the founding of jamestown(1600's) and the end of the great depression (1930's)???
December 9, 2011

english
"big and solid as twelve pounds of mashed potatoes in an eight-pound bag" is an example of what?
December 8, 2011

Physics
Thanks but that just made me more confused.
December 7, 2011

Physics
The space shuttle has a weight 2.00 x 10^7 N. The shuttle is accelerated upward at a rate of 5.50 m/s^2. What is the mass of the shuttle? What is the thrust (force) of the combined engines? What is the magnitude of the net force applied to the space shuttle?
December 7, 2011

psychology
the effects of mood and gender on proxemics
December 6, 2011

science
Earths mass is 6 x 10^24kg and its radius is 6.38 x 10^6m (6380 km ). Use the inverse-square law to show that in space-shuttle territory, 200 km above the earths surface the force of gravity on a shuttle is about 94% of that at the earths surface.
December 5, 2011

Chemistry
1) what mass of oxygen will react with 2.64g of magnesium? 2Mg + O2 -> MgO I was going to do 2.64g * (1/2) from the equation but im not sure. Do I have to add a 2 in front of the MgO? 2) How many moles of sodium ions are present in 2.50 L of 0.300 M Na3PO4? I know M=moles/L...
December 4, 2011

Chemistry
For #2 I got 55.41 from (.5184 * 106.9051) so 55.41 + 0.4816x = 107.87 -55.41 -55.41 then divide by 0.4816 The answer is 108.91amu but I did not get this.
December 4, 2011

Chemistry
1) How many miles are covered in a 15km race? (1 mile=5280, 12 in=1 ft, 1in=2.54cm) I know that I have to convert but I do not know where to start. 2) Silver (107.87amu) has two naturally occuring isotopes. In a typical sample, 51.84%of silver exists as Ag-107 (106.9051 amu). ...
December 4, 2011

Chemistry
oh i see thank you!!!
December 4, 2011

Chemistry
I know the answer for protons is 45 and electrons 50 but i do not understand where that came from
December 4, 2011

Chemistry
1)How many protons and electrons are in a sulfate ion SO4^2- ? I know the answer is 48 protons and 50 electrons but i do not know how to get this from the ion. 2) What is the charge on a sulfide ion? The answer is -2 but im not sure why. Is sulfide always -2?
December 4, 2011

Chemistry(Please help)
Disregard
December 4, 2011

Chemistry(Please help)
1)How many protons and electrons are in a sulfate ion SO4^2- ? I know the answer is 48 protons and 50 electrons but i do not know how to get this from the ion. 2) What is the charge on a sulfide ion? The answer is -2 but im not sure why. Is sulfide always -2?
December 4, 2011

Physics
Well I know density is equal to mass/volume. So I guess find both! I know that doesn't really help at all (I'm taking physics too so I understand) but maybe going back to simplicity can help! Sorry!
December 1, 2011

us history
What was Scott Joplin most known for duirng the 1920's? please do not just give me a url to a site with his biography because i have already looked at many! I am trying to narrow my answer down to 3 sentences. thanks!
December 1, 2011

5TH GRADE MATH
the rule is subtract 8. I'm not sure if thats what you're asking or not but thats my answer! Hope it helped:D
November 30, 2011

Animal Science
I need a statistic of how many dogs and cats are currently in a foster home in the us. Does anyone know a website that has this credible statistic? thanks
November 30, 2011

math
how would i find the area of the parallelogram if the area of each right triangle region is 7 1/2 square inches
November 29, 2011

Algebra (direct variation)
the value of y varies directly with x, and y=-2 when x=-4 Find y when x=8 -2=k(-4)
November 28, 2011

Math
for the point deterime all six trigonometric ratios and the value of the principal angle and the related acute angle P( -3,0)
November 26, 2011

math
a store has a total of 108 full-time staff and part time staff. There are three times as many full-time staff as part time staff. How many of the staff are in each category?
November 24, 2011

Chemistry(Please help)
Nitrogen monoxide + Hydrogen --> nitrogen + water I need to balance this equation but I do not know how. NO + H --> N + H2O 2NO + 2H --> 2N Would this be correct? Thank you!!
November 23, 2011

history
what offically started and ended WWI? and what made the us enter the war?
November 23, 2011

chemistry
sulfur dioxide (g) + oxygen (g) sulfur trioxide (g) SO2 + O = SO3 Is this correct for the balanced equation?
November 20, 2011

chemistry(Urgent Please help)
A student is asked to standardize a solution of barium hydroxide. He weighs out 0.945 g potassium hydrogen phthalate (KHC8H4O4, treat this as a monoprotic acid). It requires 33.9 mL of barium hydroxide to reach the endpoint. A. What is the molarity of the barium hydroxide ...
November 20, 2011

Chemistry
A 8.71 g sample of an aqueous solution of hydroiodic acid contains an unknown amount of the acid. If 25.0 mL of 0.388 M barium hydroxide are required to neutralize the hydroiodic acid, what is the percent by weight of hydroiodic acid in the mixture? I understand how to solve ...
November 20, 2011

speech
I am doing a persuasive speech on why you should foster a dog or cat. but I am not sure what my three main points should be. do you guys have any idea?
November 19, 2011

Chemistry
I am doing similar homeowrk and I was wondering how you calculate the ph after the equivalence point?
November 17, 2011

History
diary + the poems he wrote
November 17, 2011

History
so was his main contribution when he fuoght with the french or the diary that he kept that showed what the war was like?
November 17, 2011

History
What was Alan Seeger do that made an impact during WWI?
November 17, 2011

Chemistry
For a lab experiment we have to draw the lewis structures of hydrides. 1) Carbon It asks for the formula of hydride. Total # of valence electrons and the lewis structure. Total electrons would be four. I am not sure what the formula would be or how to find that and and the ...
November 16, 2011

Chemistry
The compound butane, has two structures. They have the same molecular formula but different arrangements of bonds in their structures. As a result, they can have different chemical and physical properties. Draw the lewis structures of all the isomers of pentane, C5H12. I am ...
November 16, 2011

geometry
why do elephants have pointy tails
November 14, 2011

Math
Your friend states that your mortgage is "an annuity where you are the bank."What does she mean?
November 10, 2011

Chemistry
Is the structure for chlorous acid H O Cl O or H Cl O ? O I was thinking that both could be correct but I am not 100% sure.
November 9, 2011

Chemistry
Is the structure for chlorous acid H O Cl O or H Cl O ? O I was thinking that both could be correct but I am not 100% sure.
November 9, 2011

physics
Two dogs pull on a toy. One pulls with a force of 10 N, the other with a force of 15 N. (a) In what relative directions can the dogs act to give the toy the smallest acceleration?
November 8, 2011

english
where in the book The Importance of Being Earnest does the author make fun of the victorian value of Social Responsibility?
November 7, 2011

Chemistry
We have to conduct a lab experiment for a photochemical reaction. We will be using a redand violet film and filter paper labeled 40W and 60W. On each piece of paper we will add 1 drop of NaCl and AgNO3 and then let it sit under a lamp to see what happens. At the end we will ...
November 2, 2011

Chemistry
ok thank you I apprieciate all of your help!!
November 2, 2011

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