Friday
March 7, 2014

# Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

ap chemistry
What is the concentration of hydrogen ions in a solution containing 0.785 M HOCN (cyanic acid) and 0.659 M (NaOCN) (sodium cyanate)? The ionization constant of cyanic acid is 3.5 × 10−4. Answer in units of M
Tuesday, February 4, 2014 at 6:57pm

ap chemistry
What is the concentration of H+ ions in a buffer solution containing 0.305 M benzoic acid (with ionization constant 6.5 × 10−5)and 0.834 M sodium benzoate (a salt of benzoic acid)?
Tuesday, February 4, 2014 at 6:56pm

ap chemistry
.......KOH + HA ==> KA + H2O I.....0.23..0.45....0....0 C....-0.23.-0.23...0.23..0.23 E......0....0.22...0.23 (KA) = 0.23 mols/0.680 L = ?M (HA) = 0.22 mols/0.680 L = ?M pH = pKa + log (base)/(acid) pH = ?
Tuesday, February 4, 2014 at 6:40pm

ap chemistry
A buffer solution is made by dissolving 0.45 moles of a weak acid (HA) and 0.23 moles of KOH into 680 mL of solution. What is the pH of this buffer? Ka = 2.4×10−6 for HA.
Tuesday, February 4, 2014 at 6:34pm

Chemistry
3 M means 3 mols/L of solution which is 3*molar ,mass NaCl = approx 175 g NaCl/L solution mass of the 1L = 1000 mL x 1.05 g/mL = 1050g solution - 175 = appox 875 g H2O or 0.875 kg. m = mols/kg solvent = about 175/0.875 = ? You need to work the problem with more accuracy than I...
Tuesday, February 4, 2014 at 6:21pm

Chemistry
A solution is 3.00M NaCl. The solution density is 1.05 g/mL. Calculate the molality?
Tuesday, February 4, 2014 at 6:12pm

Chemistry
You must describe what you are doing before we know how to answer. Probably this is a limiting reagent problem.
Tuesday, February 4, 2014 at 5:28pm

Chemistry
How many moles of dichloromethane (CH2Cl​2) would be produced if we doubled the amount of chlorine, but still had the same amount of ethene (C2H4) available in the reaction?
Tuesday, February 4, 2014 at 4:51pm

college chemistry
Linda, I answered this problem for you earlier. Don't you check your questions for responses.?
Tuesday, February 4, 2014 at 4:22pm

college chemistry
sorry, Damon. this is a word problem that is on my homework. I think they want to know the kilocalories on this.
Tuesday, February 4, 2014 at 4:05pm

college chemistry
sorry, Damon. this is a word problem that is on my homework. I think they want to know the kilocalories on this.
Tuesday, February 4, 2014 at 4:03pm

college chemistry
I do not think the 1/2 cup has anything to do with this problem. It just happens that your amounts, the 16 g, 17 g, and 5 g fit in the half cup. I will just have to believe you about kilocal per gram for each type of poison.
Tuesday, February 4, 2014 at 3:55pm

college chemistry
Yes, on the right track. The 16 x 4 will give kcal for carbs. The 17 x 9 will give kcal for fat. The 5 x 4 will give kcal for proteins. Then add all of them together for total kcal. You don't need to factor in the 1/2 cup because the problem tells you the grams of protein...
Tuesday, February 4, 2014 at 3:47pm

college chemistry
to calulate the calories(kcal) in 1/2 cup of soft ice cream that contains 16g carbs, 17g fat, 5g protein. do I multiply 16g x 4 for carbs 17g x 9 for fat 5g x 4 for proteins? then do I do conversion factors for grams to 1/2cup? am I on the right road?
Tuesday, February 4, 2014 at 3:46pm

college chemistry
to calulate the calories(kcal) in 1/2 cup of soft ice cream that contains 16g carbs, 17g fat, 5g protein. do I multiply 16g x 4 for carbs 17g x 9 for fat 5g x 4 for proteins? then do I do conversion factors for grams to 1/2cup? am I on the right road?
Tuesday, February 4, 2014 at 3:36pm

college chemistry
q = mass H2O x specific heat H2O x (Tfinal-Tintial) You choose the mass H2O specific heat = 1 Kcal/g Tfinal = 37 Tinitial = you choose. Of course it can't be 100 C (or even 90C) without causing severe burns.
Tuesday, February 4, 2014 at 2:41pm

Chemistry
the steps are right but its not al its zn.
Tuesday, February 4, 2014 at 2:38pm

chemistry
This is a limiting reagent (LR) problem. You know that because amounts are given for BOTH reactants. 6Na + Fe2O3 ==> 3Na2O + 2Fe 1. mols Na = grams/molar mass 2. mols Fe2O3 = grams/molar mass 3a. Using the coefficients in the balanced equation, convert mols Na to mols of ...
Tuesday, February 4, 2014 at 2:33pm

chemistry
What is the question?
Tuesday, February 4, 2014 at 2:26pm

Chemistry
If I can sort through this maze of hieroglyphics mols aspirin = grams/molar mass Substitute and solve for mols. m = mol/kg solvent Substitute and solve for m delta T = Kf*m Substitute and solve for delta T. Then add delta T to normal boiling point to find the new boiling point.
Tuesday, February 4, 2014 at 2:21pm

college chemistry
Ifwater cools to body temp.37 degrees C., how many kilocalories of heat could be transferred to sore muscles?
Tuesday, February 4, 2014 at 2:16pm

chemistry
a. The law of impenetrability says that two objects can't occupy the same space at the same time. So the object displaces its own volume. b. "instruments that must be followed" Are you talking about protocol or objects? c. Safety precautions for what. It sure ...
Tuesday, February 4, 2014 at 2:09pm

chemistry
a. I don't understand the question. Also, I think it matters how and where the temperature is being measured. b. clean it up. c. volumetric pipettes. volumetric flasks.
Tuesday, February 4, 2014 at 2:05pm

chemistry
You may but that isn't required. About 3 g means you could weigh 2.995, 2.900, 3.001, 3.050, 3.100, 3.200, etc. You want somewhere close to 3g and I would think anywhere between 2.500 and 3.500 would be ok. Others may think a better range is 2.750 to 3.250. It really ...
Tuesday, February 4, 2014 at 2:00pm

chemistry
3 part question If an object is completely submerged in a liquid, what volume of liquid does the object displace? List the special waste disposal instruments that must be followed. List the special safety precautions that must be taken.
Tuesday, February 4, 2014 at 1:57pm

chemistry
3 part question List the three techniques that can minimize error in measuring temperatures. What should you do if you spill anything on or near the balance? Name a piece of laboratory equipment is specifically designed to measure volumes.
Tuesday, February 4, 2014 at 1:54pm

Chemistry
mL x N x mew = grams. 20 x 0.1 x mew = 0.25 Solve for milliequivalent weight. Then equivalent weight = 1000 x mew. (molar mass/3) = equivalent weight. Solve for molar mass
Tuesday, February 4, 2014 at 1:53pm

chemistry
if you are asked to "obtain about 3 g of sodium chloride weighed to the nearest 0.001 g should you weigh out exactly 3.000 g? explain your answer.
Tuesday, February 4, 2014 at 1:50pm

Chemistry II
what is the complete & balanced equation for the following reactions & include the catalysts if any: 1. Combustion of Methane: 2. Halogenation of Cyclopentene with Br2 4. Hydrogenation of 3-methyl-1-butyne 5. Combustion of 2-methylpropene 6. Hydrohalogenation reaction between ...
Tuesday, February 4, 2014 at 12:56pm

Chemistry
If 20mL of a 0.100 M NaOH solution are required to titrate 0.25 grams of an unknown acid, what is the equivalent mass of the acid? If the acid actually contains 3 moles of H+ per mole of acid what is the molecular mass of the acid?
Tuesday, February 4, 2014 at 12:00pm

Chemistry
What is the normal boiling point in ∘ C ^\circ {\rm C} of a solution prepared by dissolving 1.50 g {\rm g} of aspirin (acetylsalicylic acid, C 9 H 8 O 4 {\rm C}_{9}{\rm H}_{8}{\rm O}_{4}) in 75.00 g {\rm g} of chloroform (CHCl 3 ) ({\rm CHCl}_{3})? The normal boiling ...
Tuesday, February 4, 2014 at 11:07am

chemistry
a 2.50-mole quatity of NOCL was initially in a 1.50-L reaction chamber at 400 degrees celcius. after equilibrium was established, it was found that 28.0 percent of the NOCL had dissociated. 2NOCL(g) <---> 2NO(g)+ Cl2(g)
Tuesday, February 4, 2014 at 10:43am

chemistry
6Na+Fe2O3=3Na2O+2Fe if Interact 100g of Na with 100g of Fe2O3,Calculate: - The resulting mass of iron?
Tuesday, February 4, 2014 at 10:05am

chemistry
348 g
Tuesday, February 4, 2014 at 10:03am

Chemistry
.07=masssugar/(350+masssugar) can you solve for the mass of sugar?
Tuesday, February 4, 2014 at 8:01am

Chemistry
How many grams of sucrose (molecular weight = 342.3 g/mol) would you dissolve in 350 ml to get a 7% solution?
Tuesday, February 4, 2014 at 7:51am

chemistry
0.80 M
Tuesday, February 4, 2014 at 6:58am

Chemistry-help
bananananananananana
Tuesday, February 4, 2014 at 4:54am

Science (Chemistry)
I hope you realize I can easily track your IP address and figure out who you are. I will not tolerate a student of mine posting homework questions online. Remove immediately, and if I catch you again I will report you and have you withdrawn from the class with a 0!
Tuesday, February 4, 2014 at 2:21am

Chemistry
I looked up the Ksp values. It would have helped if you had since my values in the book I used for Ksp values probably will not agreed with the values in your text. My book is old. Ag2SO4 ==> 2Ag^+ + SO4^2- Ksp = (Ag^+)^2(SO4^2-) Plug in Ag^+ and solve for SO4. I obtained ...
Tuesday, February 4, 2014 at 12:49am

Chemistry
Sodium sulfate is slowly added to a solution containing 0.0500 M Ca2 (aq) and 0.0370 M Ag (aq). What will be the concentration of Ca2 (aq) when Ag2SO4(s) begins to precipitate?
Tuesday, February 4, 2014 at 12:13am

chemistry
fds
Tuesday, February 4, 2014 at 12:04am

chemistry
All of them are solids for one. How many do you need? I suggest you google each, list the physical properties of each, then make a list of those in common.
Monday, February 3, 2014 at 10:46pm

Chemistry
Use PV = nRT to solve for pH2 initial. Use PV = nRT to solve for p I obtained approx 100 for pBr2 and 128 for pH2 initially but you need to go through and do it more accurately. ...........H2 + B2 ==> 2HBr I..........128..100.....0 C...........-p..-p......+2p E.......128-p...
Monday, February 3, 2014 at 10:43pm

Chemistry
A 0.960mol quantity of Br2 is added to a 1.00 L reaction vessel that contains 1.23mol of H2 gas at 1000 K. What are the partial pressures of H2, Br2, and HBr at equilibrium? At 1000 K, Kp=2.1×106 and ΔH∘ = -101.7 kJ for the reaction H2(g)+Br2(g)⇌2HBr(g).
Monday, February 3, 2014 at 9:58pm

CHEMISTRY
1.2454 = ((217+x)/(32.8-x).(13.2-x)) 324.2-58.5x+1.25x^2=0 Solved for x= 6.42 Pcl5 = 217+x=223.42 PCl3 = 13.2-x = 6.78 Cl2 = 26.38
Monday, February 3, 2014 at 8:43pm

chemistry
What physical properties of calcium chloride, citric acid, sodium iodide, potassium iodide, and sucrose have in common?
Monday, February 3, 2014 at 8:41pm

chemistry
q1 = heat needed to convert water at 25 to water at 100 q1 = mass x specific heat H2O x (Tfinal-Tinitial) (Note:) Tf is 100; Ti is 25 q2 = heat needed to convert H2O to steam. q2 = mass H2O x heat vaporization. qtotal = q1 + q2
Monday, February 3, 2014 at 6:54pm

chemistry
how many calories are needed to convert 20.0g of water at 25 Celsius to steam at 100 Celsius?
Monday, February 3, 2014 at 5:42pm

chemistry
193080
Monday, February 3, 2014 at 5:19pm

Chemistry
Simple problem and I think this guy is over thinking it. It's an intro to Chem class. Anyway you have initial temp/initial volume. Unknown secondary temp/known secondary volume. Charle's law is V1/T1 = V2/T2. I'm sure you can figure it out from here...
Monday, February 3, 2014 at 4:06pm

chemistry
how can we separate MnCl2(aq)+Na2SO4(aq)?
Monday, February 3, 2014 at 3:27pm

chemistry
A 0.25 kg length of aluminum wire is warmed 10.0°C by an electric current. How much heat was generated by the current?
Monday, February 3, 2014 at 3:16pm

Chemistry
Henry constant for the dissolving of nitrogen in water was reported as 7e-4 mol/Latm at 20 deg Celsius. What is the value of the equilibrium constant, K, at 20 deg Celsius for the process N2(g0)=N2(aq). If the amount of nitrogen in aqueous solution is .1 mol N2 and the partial...
Monday, February 3, 2014 at 2:49pm

Chemistry
27.32
Monday, February 3, 2014 at 2:36pm

Chemistry
17.7
Monday, February 3, 2014 at 10:54am

chemistry
2part question a camper obtained a sample of water from a mountain stream for cooking, but the water appeared to be cloudy with slit. what would be the best method of separating the silt from the water? Draw a flow chart for the separation you have described, using: mixture 10...
Monday, February 3, 2014 at 9:02am

chemistry
a student tried to separate a mixture of sand and red-colored water using a suction filtration apparatus. From a mixture of 10.0g of sand and 90.0g of water, the student recovered 9.5g of sand. what was the percent recovery of sand from the mixture? the sand, originally white...
Monday, February 3, 2014 at 8:57am

CHEMISTRY
HELP MY REPORT IS ABOUT SATURATED ND UNSATURATED SOLUTIONS
Monday, February 3, 2014 at 4:52am

Chemistry II
See your post above.
Monday, February 3, 2014 at 12:34am

Chemistry
delta T = i*Kf*m 2.43 = 3*1.86*m solve for m.
Monday, February 3, 2014 at 12:33am

Chemistry
What is the molal concentration of an aqueous calcium chloride solution that freezes at -2.43 degrees C?
Monday, February 3, 2014 at 12:29am

Chemistry II
What is the molal concentration of an aqueous calcium chloride solution that freezes at -2.43 degrees C?
Monday, February 3, 2014 at 12:06am

chemistry
For Au. I would change the dimensions to cm so the volume comes out in cc. volume square based pyramid is V = (1/3)*(b^2)*h = ?cc Look up the density of Au in g/cc and mass Au = density Au x volume from above. Using the conversion from grams to troy oz, convert to troy oz, ...
Sunday, February 2, 2014 at 11:56pm

chemistry
I am too, gold, I think. thanks sooo much for your help
Sunday, February 2, 2014 at 11:43pm

chemistry
yes
Sunday, February 2, 2014 at 11:37pm

chemistry
Do you want gold or rhodium? I'm confused by the problem.
Sunday, February 2, 2014 at 11:33pm

chemistry
In case the vacuum caused the flask to implode the shards of glass would be contained within the tape.
Sunday, February 2, 2014 at 11:31pm

chemistry
I would filter it with a coffee filter. I might try setting the sample aside and see if the silt would settle to the bottom, then decant it.
Sunday, February 2, 2014 at 11:30pm

chemistry
What experiment did you perform?
Sunday, February 2, 2014 at 11:28pm

Chemistry
A very general question which requires a very general answer. The student made an error in weighing or some other part of the experiment. Another possibility is that the "chemistry" of the experiment did not go as expected.
Sunday, February 2, 2014 at 11:28pm

chemistry
Rhodium metal currently costs $1251. per troy ounce (note this is different than a regular ounce! 1 troy ounce = 31.1035g). What would the cost be in dollars to purchase enough gold to form a solid square based pyramid with base dimensions 0.750m by 0.750m and height of 0.500m? Sunday, February 2, 2014 at 11:24pm chemistry mols Al = 9.1080E25 atoms/6.0221E23 = ? mols Al x atomic mass = grams Al Look up the density Al. volume = grams/density. Then volume = pi*(r^2)*h You know pi, r, and volume. Solve for h = length of the wire.Note that I would change r to meters so the answer will be in meters. Sunday, February 2, 2014 at 11:24pm chemistry A sample of aluminum metal containing 9.1080 x 10 to the 25 power atoms is drawn into a cylindrical wire with radius r=0.833 mm. how long must the wire be in meters? Sunday, February 2, 2014 at 11:01pm Science (Chemistry) After submitting the answer, this is what I received as feedback. The system is marking that the amount of moles of precipitate was incorrect, although when I did the problem originally I got the same number that you did. I am just posting this feedback for future reference, ... Sunday, February 2, 2014 at 10:22pm Chemistry 2 Sunday, February 2, 2014 at 10:11pm chemistry the suction filtration flask has been taped with strong black tape. Why was this safety precaution a good idea? Sunday, February 2, 2014 at 10:01pm chemistry A camper obtained a sample of water from a mountain stream for cooking, but the water appeared to be cloudy with silt. What would be the best method of separating the silt from the water? Sunday, February 2, 2014 at 9:59pm chemistry the sand originally white, was a light pink after drying. How could the student improve the color of sand further? Sunday, February 2, 2014 at 9:57pm Chemistry a student used a piece of copper with a mass of 2.85g and obtained 2.95g of copper at the end of the experiment, an apparent recovery of 104$. How could the student account for this result, since the best to expect is 100%.
Sunday, February 2, 2014 at 9:56pm

chemistry
Oh that's true, so you're saying to measure out the amount of methanol needed for a 0.2% solution and the amount of isopropanol needed for a 0.2% solution, adding both to the same 1 mL of water, correct?
Sunday, February 2, 2014 at 9:43pm

Chemistry
We can't draw these things on this website. The best you can do is to google "lewis dot structure CH3CH3C3COH but don't know what this is. You have 5-valent carbons and 2 valent carbon. Can't be.
Sunday, February 2, 2014 at 9:41pm

chemistry
If you interpret the question to be to prepare 0.2% solution methanol and 0.2% solution of isopropanol, and you want to put them in the same container, you add the volume of each required as if the other component were not there. Remember that if you prepare them separately ...
Sunday, February 2, 2014 at 9:38pm

chemistry
I have to prepare a 0.2% water solution of n-propanol and a water solution of methanol and isopropanol at 0.2% that can be in the same container. It didn't specify but I'm pretty sure the solutions are v/v%. For the n-propanol a 0.2% solution should just be 2mg/mL of ...
Sunday, February 2, 2014 at 9:28pm

Analytical chemistry
You want 1000 ppm Cu. You have CuSO4.5H2O; how much of that do you need? That is 1000 x (molar mass CuSO4.5H2O/atomic mass Cu) = approx 3930 g CuSO4.5H2O. That is 3930 grams CuSO4.5H2O/10^6 g solution. You don't want 10^6 g solution, only want 500 g. 500 x (3930/1E6) = ...
Sunday, February 2, 2014 at 9:26pm

Chemistry
Draw the Lewis Structures of the following compounds: CH3CH3CH3COH, H2NCOCH3, HCCCH2OH.
Sunday, February 2, 2014 at 9:26pm

Chemistry Lab
So I did a kinetics lab on the rate of reaction of peroxydisulfate ion with iodide ion. Part 1 was the effect of concentration. One of the questions asked is to calculate the amount of thiosulfate consumed in moles. My results for trial 1 were (Times taken for consumption of 1...
Sunday, February 2, 2014 at 9:25pm

chemistry
458.03
Sunday, February 2, 2014 at 9:04pm

Science (Chemistry)
Pb(NO3)2 + Na2X2O4 ==>Pb(C2O4 + 2NaNO3 millimols Pb(NO3)2 = 35 x 2.82 = approx 98.7 mmols Na2C2O4 = 20 x 0.00221 = approx 0.0442 So 0.0442 mmols PbC2O4 will be formed. (concn) = millimols/mL solution. (Pb^2+) = essentially 98.6/55 = approx 1.8M (NO3^-) = (2*98.7/55) = ? (Na...
Sunday, February 2, 2014 at 8:56pm

Chemistry
0.50M KOH = mols KOH/L solution 0.50 M KOH x 0.050 L = ? mols. Then mols = grams/molar mass. You know mols and molar mass, solve for grams.
Sunday, February 2, 2014 at 8:28pm

Chemistry
%KHCO3 = (0.95/1.50)*100 = ?
Sunday, February 2, 2014 at 8:22pm

Chemistry
Use PV = nRT to convert 2 million liters H2S gas at the conditions listed to mols. Use the coefficients in the balanced equations to convert mols H2S to mols S. That will be mols H2S x (2 mols SO2/2 mols H2S) x (3 mols S/1 mol SO2) = mols S Convert mols S to grams. g = mols S ...
Sunday, February 2, 2014 at 8:20pm

Analytical chemistry
How many grams of solid CuSO4. 5H2O are needed to prepare a 500 ml of a 1000 ppm solution of Cu?
Sunday, February 2, 2014 at 8:18pm

Chemistry
About 50% of U.S. and most Canadian sulfur is produced by the Claus process, in which sulfur is obtained from the H2S(g) that occurs in natural gas deposits or is produced when sulfur is removed from petroleum. The reactions are described by the equations 1)2H2S(g)+3O2(g)=2OS2...
Sunday, February 2, 2014 at 7:45pm

Chemistry
If you total sample mass was 1.50 g, and you determined that 0.95 g were KHCO3, what was the percent mass off the KHCO3 in the sample?
Sunday, February 2, 2014 at 7:40pm

Science (Chemistry)
A student mixes 35.0 mL of 2.82 M Pb(NO3)2(aq) with 20.0 mL of 0.00221 M Na2C2O4(aq). How many moles of PbC2O4(s) precipitate from the resulting solution? What are the values of [Pb2 ], [C2O42–], [NO3–], and [Na ] after the solution has reached equilibrium at 25 °...
Sunday, February 2, 2014 at 7:16pm

Science (Chemistry)
A student mixes 35.0 mL of 2.82 M Pb(NO3)2(aq) with 20.0 mL of 0.00221 M Na2C2O4(aq). How many moles of PbC2O4(s) precipitate from the resulting solution? What are the values of [Pb2 ], [C2O42–], [NO3–], and [Na ] after the solution has reached equilibrium at 25 °...
Sunday, February 2, 2014 at 7:16pm

Chemistry
In a similar experiment, a student needs a 0.50 M KOH solution (MM = 56.11 g/mol). The student only has a 50.00 mL volumetric flask. How much KOH should be added before the flask is filled with water?
Sunday, February 2, 2014 at 7:13pm

Chemistry
millimols = mL x M = ? NOTE: I think 20.0M acetic acid is hard to come by. 18 perhaps but not 20.
Sunday, February 2, 2014 at 6:14pm

Chemistry
20.00 ml of 20.00 M acetic acid is reacted with .1000M NaOh calculate the number of millimoles of acetic acid reacted
Sunday, February 2, 2014 at 6:08pm

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