Wednesday
July 30, 2014

Posts by hannah


Total # Posts: 2,828

Chemistry
Its suppose to be deltaT f. So would the minimum data required be Tf, Kf, and mass of solute?

Chemistry
1) The molecular mass of a substance was determined by the freezing point depression technique. The minimum data required for the determination are a. ƒ´Tf and Kf only. b. ƒ´Tf , Kf and mass of solute. c. ƒ´Tf , Kf , mass of solute and mass of ...

Chemistry
How would I find the molality of NaCl with the following information? initial temperature= 98degrees celsius final temp=100 degrees celsius. Kbp(water)=0.512

Chemistry
so delta T would be 1.86 but Im not sure what Kf would be?

Chemistry
A solution was made by dissolving 62.07 grams of a compound in 500g of water. The compound was not ionic. The freezing point of the solution was measured and found to be -1.86 degrees celsius. Using the Kf value in your textbook, the molar mass of this conpound can be calculat...

Chemistry
Ok thank you

Chemistry
27.8/80=0.3475 but I dont understand what to do next.

Chemistry
the answer choices that were given are: a)769g b)36.2g c)972g d)34.8g e)157g

Chemistry
How many grams of water are needed to dissolve 27.8g of NH4NO3 (80.0 g/mol) in order to prepare a 0.452 m (molal) solution? 27.8g / 80g/mol X 0.452 = 0.157 Is this correct?

Chemistry
would it be delta T = -5.07C/m * 0.210m?

Chemistry
1) Benzene freezes at 5.45 degrees celsius. The Kf for benzene is -5.07C/m. What would be the freezing point of a 0.210m solution of octane in benzene? I am not sure how to start this. I know the equation for freezing point is Kfp * m solute.

Chemistry
so 0.30m BaCl2 has the largest delta T at 0.90 so it has the lowest freezing point. Would you agree?

Chemistry
Ok thank you!

Chemistry
so NH4NO3 is 2 and MgS04 is 4?

Chemistry
If all ionic substances completely ionized, the aqueous solution with the lowest freezing point would be 1)0.25m NH4NO3 2)0.30m BaCl2 3) 0.35m LiBr 4) 0.50m Sucrose 5) 0.40m MgSO4 I know that i have to multiply m and i to find the largest delta T. I am just not sure if the val...

Chemistry
Which of the following contributes to the bubbling from a cold can of soda when left standing at room temperature. Choose all that apply. 1) the initial rush of CO2 out of the can drags other CO2 molecules out of the solution. 2) the decrease in CO2 partial pressure lowers the...

Chemistry
Thank you for all your help!!

Chemistry
Which aqueous solution below is expected to have the lowest freezing point? Assume 100% dissociation for ionic species. 1)0.25m MgBr2 2)0.30m Na2SO4 3) 0.50m KCl 4) 1.0m sucrose 5) 0.40m Cr(NO3)3 I think that the answer is 0.30NaSO4 but I am not positive. Is this correct? Chem...

Chemistry(Please check)
1) The molecular mass of a substance was determined by the freezing point depression technique. The minimum data required for the determination are: a) delta T and Kf only b) delta T, Kf, and mass of solute c) delta T, Kf, mass of solute, and mass of solvent d) delta T, Kf, m...

Physics
A 520 Hz tuning fork produces a standing wave in a column of air in a closed tube. If the speed of sound is 340 m/s, what is the length of the air column?

physics
a) What is the frequency of a photon of UV radiation ( = 2.00 x 10^-7 m)? (b) Calculate the energy of a photon of UV radiation. (C) What is the frequency of a photon of infrared radiation ( = 1.083 x 10^-6 m)? (d) Calculate the energy of a photon of infrared radiation. (e) How...

Physics
In black-and-white photography, a photon energy of about 4.00 x 10-19 J is needed to bring about the changes in the silver compounds used in the film. (a) What is the frequency of the light needed to bring about these changes? (b) Explain why a red light used in a darkroom do...

Chemistry
when 7.50 grams of iodine (I2) is added to 48.7grams of carbon tetrachloride (CCl4), the iodine dissolves and a solution is formed. The weight percent of the iodine in the solution is? 7.50g I2/ 7.50 + 48.7 X 100 = 13.3 Did I do this correctly?

Chemistry(Please check)
Ok now I got 0.0931, so this is the mole fraction for NaCl?

Chemistry(Please check)
Ok so 100/58.44= 1.71

Chemistry(Please check)
1) If exactly 100.0 grams of NaCl (mm=58.44g/mol) are dissolved in 300 grams of water (mm=18.02g/mol), the mole fraction of NaCl is? a) 1.71 b) 0.0932 c) 0.250 d) 0.103 e) 4.75 I did 100g / 100g + 300g = 100/40 = 0.250. Did I do this correctly?

Chemistry(Please check)
1) The molecular mass of a substance was determined by the freezing point depression technique. The minimum data required for the determination are: a) delta T and Kf only b) delta T, Kf, and mass of solute c) delta T, Kf, mass of solute, and mass of solvent d) delta T, Kf, ma...

Chemistry(Please check)
Thank you!

Chemistry(Please check)
1)For electrolyte solutions, the _____ the concentration of the electrolyte and the ____ the ion charges, then the ____ the ion-pairing. a) lower, smaller, greater b) higher, smaller, smaller c) higher, greater, greater d) lower, greater, smaller e) lower, greater, greater I c...

chemistry(Please check)
ok thank you

chemistry(Please check)
1) In comparing the phase diagram for water with that of a solution of sugar in water, all of the following decrease except a) the vapor pressure b) the boiling point c) the freezing point d) the triple point I chose the boiling point as the answer. Is this correct? Thank you.

Chemistry
Ok so then I just have to find the mass of each solution so KCl = 74.55 X 2 MgBr2 = 184.11 X 3 Na2SO4 = 94.05 X 3 Cr(SO4)3 = 340.21 X 4 So Cr(SO4)3 would have the largest delta T, so the lowest freezing point. Is this correct?

Chemistry
I understand everything except the van't Hoff factor part. I do not understand how you figure that out.

Chemistry
Which aqueous solution below is expected to have the lowest freezing point? Assume 100% dissociation for ionic species. 1)0.25m MgBr2 2)0.30m Na2SO4 3) 0.50m KCl 4) 1.0m sucrose 5) 0.40m Cr(NO3)3 I think that the answer is 0.30NaSO4 but I am not positive. Is this correct?

Chemistry
The following information is given for ether, C2H5OC2H5, at 1atm: boiling point = 34.6oC Hvap(34.6oC) = 26.5 kJ/mol melting point = -116oC Hfus(-116oC) = 7.27 kJ/mol specific heat liquid = 2.32 J/goC At a pressure of 1 atm, what is H in kJ for the process of condensing a 33.7 ...

Physics
15 At a particular location and time, sunlight is measured on a 1 m2 solar collector with an intensity of 500.0 W. If the peak intensity of this sunlight has a wavelength of 5.60 x 10-7 m, (a) What is the frequency of this light? When you input large numbers such as those in t...

Physics
What is the frequency of the electromagnetic radiation from outer space that reaches the earth with a wavelength of 1 x 105 m, and a velocity of 1 x 105 m/s?

physics
Calculate the distance traveled in 6.00 s as a given sound moves through (a) water at 25.0ºC in m/s; (b) water at 25.0ºC in ft/s; (c) seawater at 25ºC in m/s; and (d) seawater at 25ºC in ft/s.

Physics
The lower frequency limit for human hearing is usually considered to be 20.0 Hz. (a) What is the speed of sound in m/s if the air temperature is 20.0ºC? (b) What is the corresponding wavelength for this frequency?

physics
A glass bottle of soda is sealed with a screw cap. The absolute pressure of the carbon dioxide inside the bottle is 1.50 x 105 Pa. Assuming that the top and bottom surfaces of the cap each have an area of 4.20 x 10-4 m2, obtain the magnitude of the force that the screw thread ...

physics
The density of ice is 917 kg/m3, and the density of sea water is 1025 kg/m3. A swimming polar bear climbs onto a piece of floating ice that has a volume of 4.41 m3. What is the weight of the heaviest bear that the ice can support without sinking completely beneath the water? p...

ap chemistry
for the following, mix the equal volumes of one solution from group I with one solution from group II to achieve the indicated pH. calculate the pH of each solution. Group I: .2M NH4Cl, .2M HCl, .2M C6H5NH3Cl, .2M (C2H5)3NHCl Group II: .2M KOI, .2M NaCN, .2M KOCl, .2M NaNO2 a....

Chemistry
Nevermind I actually figured it out. Thank you.

Chemistry
Ok when I did the graph I got -2.99e3 as the slope. Is this the answer or do I have to do something else now?

Chemistry
The vapor pressure of the liquid HF is measured at different temperatures. The following vapor pressure data are obtained. Temperature(K) Pressure mmHg 250 129.63 260 206.65 270 318.22 280 475.16 Determine the enthalpy of vaporization. I have know idea how to start this. Thank...

Chemistry
ln 555.6/281.1 = -deltaH vap/8.314J/k mol [1/256.1K - 1/242K]. I have to solve for delta Hvap. I know that the left side would be7.21. I am not sure what step to do next.

physics
n boat starts from rest and accelerates at a constant rate to a final speed of 28 m/s over a distance of 780 m. How much time will this take?

Chemistry
Ok thank you. I know what I was doing wrong. I was just hitting the e^x button and I was getting a different answer. I have to hit the 2nd button first and then e^x on my calculator.

Chemistry
ln p2/368.3 mm Hg = -24900 J/mol / 8.314 J/k mol [1/259.7K - 1/247.4K] I am having trouble doing the mathto solve for p2. Chemistry - DrBob222, Sunday, February 5, 2012 at 12:44pm The easy way is to calculate 1/259 = ? and 1/247 = ?, then subtract them and multiply that by -24...

geometry
ABCD is a rhombus with diagonals intersecting at E. If m<ABC is three times m<BAD, find m< EBC

Chemistry(Please help, thank you)
Thank you

Chemistry(Please help, thank you)
1/2.165 = sqrt x/131.29. I am not sure how to solve for x.

Chemistry
1/2.165 = sqrt x/131.29. I am not sure how to solve for x.

Chemistry
I got 23.6. Is this correct?

Chemistry
The heat of vaporization of benzene, C6H6, is 30.8kJ/mol at its boiling point of 80.1 degrees celsius. How much energy in the form of heat is required to vaporize 102g of benzene at its boiling point? I know that the answer is 24.2kJ but i am not sure how to get this.

Chemistry
For some reason on my computer the answer that was posted was sort of cut of so I had a hard time reading it but when I did 1/259 - 1/247 I got -0.00018 then I multiplied by -24900 and divided by 8.314 and got 0.539. Then I took the sqrt of this number and ended up with p2/368...

Chemistry
ln p2/368.3 mm Hg = -24900 J/mol / 8.314 J/k mol [1/259.7K - 1/247.4K] I am having trouble doing the mathto solve for p2.

Physics
Thank you for your help!

Physics
(a) How much heat in kcal must be provided for a 0.853 kg block of lead to raise the temperature of 0.015 kg block of ice from -5ºC to 0ºC? (b) How much heat in kcal must be provided for a 0.853 kg block of lead to melt a 0.015 kg block of ice from at 0ºC? (c) H...

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.

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)...

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)...

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?

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?

Poetry
Thanks

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:)

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...

Chemistry
Ok well thank you for trying!

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 f...

speech
What is the diference between formal and technical language in speech? thanks

Chemistry
How should I go about solving this problem? Am I missing information?

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 f...

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...

Chemistry
ok thank you!!

Chemistry
Why is it that the straight chain is higher?

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?

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

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 evapora...

Chemistry
ok

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.

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.

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 &l...

Chemistry
Is number 1 correct because I thought that was the one that was incorrect?

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 evapora...

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 ei...

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) diff...

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 correct...

Chemistry
So choice b is not correct either?

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-dip...

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?

Chemistry
Ok so would you say just high boiling point and low vapor pressure?

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...

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?

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 ...

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

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?

Chemistry(Please check)
ok thank you

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

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 < Lond...

English
its number one...

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