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October 1, 2014

Posts by hannah


Total # Posts: 2,869

Chemistry
The following thermochemical equation is for the reaction of iron(s) with chlorine(g) to form iron(III) chloride. 2Fe(s) + 3Cl2(g) 2FeCl3(s) H = -799 kJ How many grams of Fe(s) would have to react to produce 107 kJ of energy? I am not sure how to start this.
February 4, 2012

Chemistry(Please help, thank you)
Find the value of delta H net for the following equation: SnBr2(s) + TiCl4(l) -> TiBr2(s) + SnCl4(l) Use the following reactions to help solve for the net value: 1) SnCl2(s) + TiBr2(s) -> SnBr2(s) + Ticl2(s) Delta H=+4.2 2) SnCl2(s) + Cl2(g) -> TiCl4(l) deltaH=-195 3...
February 4, 2012

Chemistry
Find the value of delta H net for the following equation: SnBr2(s) + TiCl4(l) -> TiBr2(s) + SnCl4(l) Use the following reactions to help solve for the net value: 1) SnCl2(s) + TiBr2(s) -> SnBr2(s) + Ticl2(s) Delta H=+4.2 2) SnCl2(s) + Cl2(g) -> TiCl4(l) deltaH=-195 3...
February 4, 2012

Physics
The heat of fusion of water is 80 cal/g. When 25 g of ice at 0ºC is placed in the contents of a 12 oz can of Coke (≈350 g) at 25ºC, what is the final temperature of the beverage?
February 4, 2012

Physics
Eighty calories must be added to one gram of ice at 0ºC to melt it. What is the approximate mechanical equivalent of this amount of energy?
February 4, 2012

Poetry
Thanks
February 4, 2012

Poetry
Without knowing the context of of the poem, does this poem title stand out to you, get your attention, and sound good? He Makes Our Joy Full also. do you normally capitalize all words in a poems title or is that just for books? thanks:)
February 4, 2012

Chemistry
I dont know if this will help but I realized there was more information for the problem. 1) SnCl2(s) + TiBr2(s) -> SnBr2(s) + Ticl2(s) Delta H=+4.2 2) SnCl2(s) + Cl2(g) -> TiCl4(l) deltaH=-195 3) TiCl2(s) + Cl2(g) ->TiCl4(l) deltaH=-273 SnCl2(s) + Cl2(g) -> SnCl4(l...
February 3, 2012

Chemistry
Ok well thank you for trying!
February 3, 2012

Chemistry
Find the value of delta H net for the following equation: SnBr2(s) + TiCl4(l) -> TiBr2(s) + SnCl4(l) I know that I already posted this once but I am still lost on what to do. I know that TiCl4=-804.2 and SnCl4=-511.3 but I thought that the values for SnBr2 is 0 as well as ...
February 3, 2012

speech
What is the diference between formal and technical language in speech? thanks
February 2, 2012

Chemistry
How should I go about solving this problem? Am I missing information?
February 1, 2012

Chemistry
Find the value of delta H net for the following equation: SnBr2(s) + TiCl4(l) -> TiBr2(s) + SnCl4(l) I know that I already posted this once but I am still lost on what to do. I know that TiCl4=-804.2 and SnCl4=-511.3 but I thought that the values for SnBr2 is 0 as well as ...
February 1, 2012

Chemistry
How many kilograms of water at 15oC can be heated to 95oC by burning 143 grams of methane, CH4, assuming that 100% of the heat is used to heat the water. The heat of combustion of methane is 891 kJ per mole of methane. (The specific heat of water is 4.184 J/goC.) I am not sure...
January 30, 2012

Chemistry
ok thank you!!
January 30, 2012

Chemistry
Why is it that the straight chain is higher?
January 30, 2012

Chemistry
1)Which compound below would be expected to have the highest boiling point? a) CH3-CH2-CH2-CH2-CH2-CH2-CH3 b) CH3-CH2-CH2-CH2-CH-CH3 | CH3 c) CH3-CH-CH2-CH-CH3 | | CH3 CH3 d) CH3 | CH3-CH-C-CH3 | | CH3 CH3 Do I use molar mass to determine which is the highest?
January 30, 2012

Chemistry
oh ok I understand now, thank you for your help!
January 30, 2012

Chemistry
1) Three factors control the rate of evaporation of a liquid: surface area, temperature, and strengths of intermolecular forces. More than one of the statements given described a correct effect. The statements are (1) the larger the surface area, the faster the rate of ...
January 30, 2012

Chemistry
ok
January 29, 2012

Chemistry
for TiCl4 i got -804.2 and for SnCl4 I got -511.3 and then i subtracted them to get -292.9 but I dont think this is right.
January 29, 2012

Chemistry
1) Determine the value of delta H net for the following equation: SnBr2(s) + TiCl4(l) -> TiBr2(s) + SnCl4(l) I am not sure how to solve this.
January 29, 2012

Chemistry
1) Given the following “substances” and their normal boiling points, in celsius. G:43.8 Celsius J:93.7 M:56.7 T: 83.5 R:63.6 Which set below correctly lists some of these liquids in order of increasing intermolecular forces at 20 oC? a) G < R < J b) J < T &...
January 29, 2012

Chemistry
Is number 1 correct because I thought that was the one that was incorrect?
January 29, 2012

Chemistry
1) Three factors control the rate of evaporation of a liquid: surface area, temperature, and strengths of intermolecular forces. More than one of the statements given described a correct effect. The statements are (1) the larger the surface area, the faster the rate of ...
January 29, 2012

Chemistry
1) Which of the following molecular solids will exhibit dipole-dipole intermolecular forces: NH3, BF3, I2 and H2S? a) NH3, and H2S (correct) b) NH3, BF3, and H2S (BF3 has polar bonds, but is a nonpolar molecule) c) I2 only d) BF3 and I2 e) NH3, BF3, I2 and H2S I think that ...
January 29, 2012

Chemistry
1) The order of the boiling points for the hydrogen halides, except for HF, is HI > HBr > HCl. The reason for this order can be attributed to a) the relative covalent bond strengths. b) differences in hydrogen bonding. c) differences in dipole-dipole attractions. d) ...
January 29, 2012

Chemistry
1) Which one of the following molecules is the most polarizable? a) H3C – I b) H3C – CH3 c) H3C – F d) H3C – H e) H3C – OH I chose H3C-I as the answer because the mm was the greatest. I added the mm of H, C, and I and got 141.934. Did I do this ...
January 29, 2012

Chemistry
So choice b is not correct either?
January 29, 2012

Chemistry
1. Which of the following statements concerning dipole-dipole attractions is correct? a) Dipole-dipole attraction is a weaker force than covalent bonds, being about 50% as strong. b) Dipole-dipole attractions increase as the distance between the dipoles increase. c) Dipole-...
January 29, 2012

Chemistry(Please check)
1) Which one of the following molecules is the most polarizable? a) H3C – I b) H3C – CH3 c) H3C – F d) H3C – H e) H3C – OH I chose H3C-I as the answer because the mm was the greatest. I added the mm of H, C, and I and got 141.934. Did I do this correctly?
January 29, 2012

Chemistry
Ok so would you say just high boiling point and low vapor pressure?
January 29, 2012

Chemistry
1) Which of the following properties of water can be explained using hydrogen bonding arguments? 1. its ability to dissolve most ionic compounds. 2. its high boiling point. 3. its low vapor pressure a) only 1 or only 2 or only 3 b) 1 and 2 only c) 1 and 3 only d) 2 and 3 only...
January 29, 2012

Physics
A weight lifter performs a clean and jerk on 150 kg, raising it 2 m above the ground in 1.5 s. What is his power output during the lift?
January 29, 2012

Chemistry(Please check)
1) Which of the following properties of water can be explained using hydrogen bonding arguments? 1. its ability to dissolve most ionic compounds. 2. its high boiling point. 3. its low vapor pressure a) only 1 or only 2 or only 3 b) 1 and 2 only c) 1 and 3 only d) 2 and 3 only ...
January 29, 2012

Chemistry(Please check)
Oh ok thank you I will look over it again.
January 28, 2012

Chemistry(Please check)
1) Where in the phase diagram of a compound do all phases exist together? a) at the sublimation point b) at the boiling point c) at the melting point d) at the critical point e) at the triple point I chose answer E, the triple point. Is this correct?
January 28, 2012

Chemistry(Please check)
ok thank you
January 28, 2012

Chemistry(Please check)
O ok so it is london forces,dipole,then hydrogen?
January 28, 2012

Chemistry(Please check)
1) For a series of small molecules of comparable molecular mass, which of the following choices lists the intermolecular forces in the correct increasing order? a) dipole-dipole forces < London forces < hydrogen bonds b) hydrogen bonds < dipole-dipole forces < ...
January 28, 2012

English
its number one...
January 26, 2012

physics
Sound travels around 340 m/s in air. If a bat squeaks and hears the echo of its squeak return to it 6 seconds later, how far away is the insect which the bats squeak encountered? This question doesnt even make sense to me!! Does anyone have a formula that I can use to try and ...
January 25, 2012

physics
Sound travels around 340 m/s in air. If a bat squeaks and hears the echo of its squeak return to it 6 seconds later, how far away is the insect which the bats squeak encountered? This question doesnt even make sense to me!! Does anyone have a formula that I can use to try and ...
January 25, 2012

Chemistry
Ok thank you for your help!!
January 22, 2012

Chemistry
An insulated beaker contains 250g of water at 25 degrees celsius. Exactly 41.6g of a metal at 100 degrees celsius was dropped in the beaker. The final temperature of the water was 26.4 degrees celsius. Assuming that no heat is lost in any other way, calculate the specific heat...
January 22, 2012

Chemistry
A chemical reaction is run in which 132 joules of work is done by the system amd the internal energy changes by 469 joules. Calculate the amount of heat transferred. u=q+w I was going to do 469 = q + 132 but I think this is wrong.
January 22, 2012

Chemistry
Ok thank you for your help!
January 22, 2012

Chemistry
I did 30kJ X 26.9815/4.00 = 202.36 One of the anser choices that is given is -202 kJ. Is this incorrect or did I do the calculation wrong?
January 22, 2012

Chemistry
For the reaction Al(s) + 3 HCl(aq)->AlCl3(s) +3/2 H2(g) it was observed that when 4.00g of aluminum reacted with excess HCl, exactly 30,0 kJ of heat was released. What is the delta H for this reaction? I do not understand how to get the delta H value.
January 22, 2012

Chemistry
Ok I got 54.9 which would round to 55 which is an answer choice that they gave me.
January 22, 2012

Chemistry
I am having trouble with getting Tf by itself thats all.
January 22, 2012

Chemistry
A cup of teat containing 400g of liquid at 20 degrees celsius was heated. If 58.5 kj of heat was absorbed by the tea, what would the final temperature be? Assume that the specific heat of the tea is the same as that of water (4.18). I am not sure how to start this problem. ...
January 22, 2012

Physics
You have 2 photos of a bicyclist. One shows the rider at the corner of Third and Main streets, the other shows the rider at Twentieth and Main. There are lampposts at every corner in this town, and the first picture shows it to be 10:32:00 exactly. The second picture shows it ...
January 22, 2012

Chemistry
O ok I thought that b was correct also but I see now why it is not.
January 21, 2012

Chemistry
2)Which of the following equations represents a reaction for which the delta H can be called a standard enthalpy of formation, delta Hf? a) FeO(s) + CO2(g) -> FeCO3(s) b) 1/2 N2(g) + 2 O(g) -> NO2(g) c) 2 Na(s) + Cl2(g) -> 2 NaCl(s) d) Ba(s) + N2(g) + 3 O2(g) -> Ba...
January 21, 2012

Chemistry
I did 400/58.5 (4.18) and got 28.6 degrees celsius. Was I suppose to use the 20 degrees that was stated in the problem?
January 21, 2012

Chemistry
so I did 4.18 = 400 X 58.5 X (Tf-30) 4.18 =I amnot sure what to do on this side. Do I multiply 400, 58.5 and 30?
January 21, 2012

Chemistry
A cup of teat containing 400g of liquid at 20 degrees celsius was heated. If 58.5 kj of heat was absorbed by the tea, what would the final temperature be? Assume that the specific heat of the tea is the same as that of water (4.18). I am not sure how to start this problem.
January 21, 2012

Chemistry
Yes all the units are kJ.
January 21, 2012

Chemistry
Did I do this correctly?
January 21, 2012

Chemistry
1) Consider the formation of sulfur trioxide according to the reaction: 2 SO2(g) + O2(g) -> 2 SO3(g) delta H = -198 How much heat is evolved in the formation of 750 grams of SO3? So I did 193 X (750/2*80.0642) = 904. The answer choices given are 10.6, 928, 1.86 X 10^3, 7.43...
January 21, 2012

Chemistry
So I did 193 X (750/2*80.0642) = 904. The answer choices given are 10.6, 928, 1.86 X 10^3, 7.43 X 10^4, 3.71 X 10^3 And how did you get 193?
January 20, 2012

Chemistry
1) Consider the formation of sulfur trioxide according to the reaction: 2 SO2(g) + O2(g) -> 2 SO3(g) delta H = -198 How much heat is evolved in the formation of 750 grams of SO3? I am not sure how to start this problem.
January 20, 2012

Chemistry(Please check)
Ok for number one i got 0.129 and for number 2 did you mean that my answer choice of e was correct or that just equation d is correct? Thank you for your help!!
January 20, 2012

Chemistry(Please check)
1)A piece of metal with a mass of 5.50 grams changed in temperature from 25 to 55 degrees celsius when 21.3 joules was absorbed. What is the specific heat of the metal? a)0.256 b)0.129 c)3.91 d) 7.75 e)0.710 Jg^-1 C^-1 I chose 7.75 because I did 5.50/21.3 and then multiplied ...
January 20, 2012

Chemistry
The four statements below are used for applications of Hess's law. One of the statements is erroneous. Choose that statement. a) the value of delta H for any reaction that can be written in steps is the sum of the values of delta H for each of the individual steps. b) when...
January 20, 2012

chemistry(Please check)
Thank you for checking my work!!!
January 20, 2012

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

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