Saturday
April 19, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Post a New Question | Current Questions

Chemistry
How much water is needed to prepare 8M of NaOH solution with 1kg of NaOH pellets?
Wednesday, February 26, 2014 at 9:02am

chemistry
at an equilibrium mixture of PCl5, PCl3, and Cl2 has partial pressures of 217.0 Torr, 13.2 Torr and 13.2 Torr respectively. a quantity of Cl2 is injected into the mixture, and the total pressure jumps to 263.0 Torr (at the moment of mixing). the system then re-equilibrates. ...
Wednesday, February 26, 2014 at 5:14am

Chemistry
A molecular compound has the empirical formula CH2. When 100mg of the compound is dissolved in 1.00 g of benzene, the solution freezes 1.75 degrees celsius lower than pure benzene. The Kf for benzene is 4.90 C/m. What is the MM of the compound?
Wednesday, February 26, 2014 at 1:44am

chemistry
from what? If s/he produced it from shoe leather I would call it a phenomenal percent yield. If from 45 g Na2CO3 it is only 100% yield.
Wednesday, February 26, 2014 at 12:11am

chemistry
mols KI = grams/molar mass Then M = mols/L solution.
Wednesday, February 26, 2014 at 12:09am

chemistry
if a college student went into the lab and produced 45 grams of Na2CO3, what is percent yield of this trial?
Tuesday, February 25, 2014 at 11:29pm

chemistry
What is the molarity of a solution composed of 2.23 g of potassium iodide (KI) dissolved in enough water to make 0.181 L of solution? Answer in units of M
Tuesday, February 25, 2014 at 11:25pm

Chemistry
(NaOH) = 0.190M x (1.90 mL/1500 mL) = ?
Tuesday, February 25, 2014 at 9:55pm

Chemistry
Calculate [OH−] for 1.90mL of 0.190M NaOH diluted to 1.50L .
Tuesday, February 25, 2014 at 9:45pm

Chemistry 1150
heat lost by warm water + heat gained by cool water = 0 [mass warm water x specific heat water x (Tfinal-Tinitial)] + [mass cool H2O x specific heat H2O x (Tfinal-Tinitial)] = 0 Solve for Tfinal. Watch the units.
Tuesday, February 25, 2014 at 9:44pm

Chemistry
One day at the fertilizer factory, your boss Mr. Haber comes to you with a problem. The process used by the factory to produce ammonia,the raw material for your fertilizer, is just not optimized. He would like to modify the conditions to achieve a better yield of ammonia in ...
Tuesday, February 25, 2014 at 9:24pm

Chemistry 1150
Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the following endothermic reaction: NH4NO3(s)→NH+4(aq)+NO...
Tuesday, February 25, 2014 at 9:14pm

Chemistry
When 10.00g of phosphorus is burned in O2(g) to form P4O10(s), enough heat is generated to raise the temperature of 2990g of water from 18.0 ∘C to 38.0 ∘C. Calculate the heat of formation of P4O10(s) under these conditions. -------------------------------------- ...
Tuesday, February 25, 2014 at 9:03pm

Chemistry
Calculate the total heat energy needed to convert 110g of ice at -10°C to steam at 110°C..?
Tuesday, February 25, 2014 at 9:02pm

chemistry
You must want the head of solidification which is the heat fusion. For H2O that is 80 cal/grams
Tuesday, February 25, 2014 at 8:56pm

chemistry
I would have answered that k2o is unknown. I agree that K2O is potassium oxide.
Tuesday, February 25, 2014 at 8:52pm

chemistry
CH4 is not. CF4 is not CH3F is. All three molecules are tetrahedral shapes. The C-H bonds are slightly polar BUT the tetrahedral shape is symmetrical and the individual bond polarities cancel so the overall polarity is zero for the molecule. Same argument for CF4. However, for...
Tuesday, February 25, 2014 at 8:51pm

chemistry
Is deltaH standard of TdeltaS standard more important in determining whether KHT will be soluble in water at a given temperature?
Tuesday, February 25, 2014 at 8:48pm

Chemistry
See your other post.
Tuesday, February 25, 2014 at 8:45pm

Chemistry
Yes, 0.206 mol HCl remaining is exactly right; however you went around the barn to work the problem. Here is an easier way. Let's say you've already determined that FeS is the limiting reagent. So 0.223 mols FeS x (2 mols HCl/1 mol FeS) = 0.446 mols HCl used. 0.652 ...
Tuesday, February 25, 2014 at 8:41pm

Chemistry
The problem asked to find the amount (in moles) of reactant left. .223moles FeS and .652moles of HCl FeS+2HCl--> FeCl2+H2S .223molFeS(1moleFeCl2/1moleFeS)=.223mole​FeCl2 .652molHCl(1moleFeCl2/2molHCl)=.326moleF​eCl2 .223/.326x100=68.4% used HCL 100-68.4=31.6% ...
Tuesday, February 25, 2014 at 8:30pm

Chemistry
The problem asked to find the amount (in moles) of reactant left. .223moles FeS and .652moles of HCl FeS+2HCl--> FeCl2+H2S .223molFeS(1moleFeCl2/1moleFeS)=.223mole​FeCl2 .652molHCl(1moleFeCl2/2molHCl)=.326moleF​eCl2 .223/.326x100=68.4% used HCL 100-68.4=31.6% ...
Tuesday, February 25, 2014 at 8:30pm

chemistry
which of the following tetrahedral molecules is polar? please explain CH4 CF4 CH3F thanks
Tuesday, February 25, 2014 at 8:18pm

Chemistry
yes.
Tuesday, February 25, 2014 at 8:15pm

chemistry
potassium oxide as far as I know
Tuesday, February 25, 2014 at 8:13pm

chemistry
what is the correct name for k2o
Tuesday, February 25, 2014 at 8:07pm

chemistry
50 g * heat of vaporization of water I do not know if you are using calories or Joules or BTU. Use whatever but convert your grams properly
Tuesday, February 25, 2014 at 8:03pm

Chemistry
The problem asked to find the amount (in moles) of reactant left. .223moles FeS and .652moles of HCl FeS+2HCl--> FeCl2+H2S .223molFeS(1moleFeCl2/1moleFeS)=.223mole​FeCl2 .652molHCl(1moleFeCl2/2molHCl)=.326moleF​eCl2 .223/.326x100=68.4% used HCL 100-68.4=31.6% ...
Tuesday, February 25, 2014 at 8:00pm

chemistry
how much energy is released to the environment by 50.0 grams of condensing water vapor?
Tuesday, February 25, 2014 at 7:47pm

chemistry
what is the solidification for water?
Tuesday, February 25, 2014 at 7:44pm

College Chemistry
And I have no intention of working this problem BUT I certainly can tell you where to start. You ALWAYS start by writing and balancing the equation. H2O2 + KMnO4 ==> a. You have density and grams KMnO4 solution, convert g to mL. b. You now have mL and molarity KMnO4, mols...
Tuesday, February 25, 2014 at 7:07pm

chemistry
g C = 2.20g CO2 x (atomic mass C/molar mass CO2) = about 0.6g g H = 0.4g H2O x (2 atomic mass H/molar mass H2O) = 0.044 g O = 1.00g - g C - g H Note: you need to redo all of this more accurately than I've done them. Convert to mols mols C = 0.6/12 = about 0.05 mols H = 0....
Tuesday, February 25, 2014 at 6:57pm

Chemistry
empirical formula mass = about 12 + 1 + 35.5 = 48.5 (CHCl)x = 290.8 x*48.5 = 290.8 x = approx 5.996 which we round to 6 so the formula is (CHCl)6 or C6H6Cl6
Tuesday, February 25, 2014 at 6:34pm

Chemistry
The empirical formula of a group of compounds is CHCl. Lindane, a powerful insecticide, is a member of this group. The molar mass of lindane is 290.8 g/mol. How many atoms of carbon does a molecule of lindane contain?
Tuesday, February 25, 2014 at 6:24pm

chemistry
You take an aspirin tablet (a compound consisting solely of carbon, hydrogen, and oxygen) with a mass of 1.00 g, combust it under an oxygen atmosphere, and collect 2.20 g of carbon dioxide and 0.400 g water. The molar mass of aspirin is between 170 and 190 g/mol. The molecular...
Tuesday, February 25, 2014 at 6:23pm

Chemistry
Possible Sources of error in a reaction or sodium bicarbonate and acetic acid. Also known as baking soda and vinegar.
Tuesday, February 25, 2014 at 5:42pm

Chemistry
See your post above.
Tuesday, February 25, 2014 at 5:29pm

Chemistry
mols NaOH = M x L = ? 1 mol NaOH = 2 mol ascorbic acid g ascorbic acid = mols x molar mass %asc = (g asc/mass sample)*100 = ?
Tuesday, February 25, 2014 at 5:28pm

Arrhenius Reaction
Roses are red, Violets are blue, I'm terrible at Chemistry And apparently, you are too <3
Tuesday, February 25, 2014 at 5:20pm

Chemistry
How would I find the collision frequency factor with this information? Slope- -8111.4 EA- 74089.36 j/mol y-int 24.897 1/T .003
Tuesday, February 25, 2014 at 5:14pm

AP Chemistry
You could work out each one? right?
Tuesday, February 25, 2014 at 4:47pm

AP Chemistry
Which solution has the highest pH? 1. 0.1 M C6H5NH3Cl, Kb C6H5NH2 = 4.2 × 10−10 2. 0.1 M NH2(OH)2Cl, Kb NH2OH = 6.6 × 10−9 3. 0.1 M NaCl, Kb  zero 4. 0.1 M NH4Cl, Kb NH3 = 1.8 × 10−5 5. 0.1 M CH3NH3Cl, Kb CH3NH2 = 5.0 × 10−4
Tuesday, February 25, 2014 at 4:30pm

Chemistry
Element P electron configuration is 2-8-8-1 Element Q electron configuration is 2-8-18-7
Tuesday, February 25, 2014 at 4:25pm

Chemistry
The element P (mass no.=39) and Q (mass no. =80) contain 20 and 45 neutrons respectively in their nucleus. Give their electron configuration separately
Tuesday, February 25, 2014 at 4:09pm

College Chemistry
The density of a 0.0122 M KMnO4 is 1.037 g/mL. Suppose 26.35 g of 0.0122 M KMnO4 are required to titrate 1.072 g of a household H2O2 solution. a)Calculate the mL of MnO4^- added to reach the endpoint. b)Calculate the moles of MnO4^- added to reach the endpoint. c)Calculate the...
Tuesday, February 25, 2014 at 3:47pm

Chemistry
Ascorbic acid (vitamin C) is a diprotic acid having the formula H2C6H6O6. A sample of a vitamin supplement was analyzed by titrating a 0.3252 g sample dissolved in water with 0.0284 M NaOH. A volume of 13.27 mL of the base was required to completely neutralize the ascorbic ...
Tuesday, February 25, 2014 at 2:11pm

Chemistry
Ascorbic acid (vitamin C) is a diprotic acid having the formula H2C6H6O6. A sample of a vitamin supplement was analyzed by titrating a 0.3252 g sample dissolved in water with 0.0284 M NaOH. A volume of 13.27 mL of the base was required to completely neutralize the ascorbic ...
Tuesday, February 25, 2014 at 1:48pm

Chemistry
First off, remember HI is a strong acid; i.e., it ionizes 100%. Therfore, (H^+) = (HI). mols HI = grams/molar mass M HI = mols HI/L solution (H^+) = (HI) pH = -log(H^+) 5 is done the same way since HNO3 is a strong acid also. I should point out it is stated incorrectly. The ...
Tuesday, February 25, 2014 at 12:35pm

chemistry
..........PCl5 --> PCl3 + Cl2 E.........217.......13.2 13.2 Kp = pPCl3*pCl2/pPCl5. Substitute the E line into Kp expression and solve for Kp. Cl2 added. Total P = 217 + 13.2 + 13.2 = 243.4 New total P = 263 Cl2 added = 263-243.4= 19.6 torr New Cl2 = 19.6 + 13.2 = 32.8 torr...
Tuesday, February 25, 2014 at 12:29pm

Chemistry
3.a solution has 64 grams of HI dissolved in 250 L of water. what is its [H+] 4. What is the pH of the solution in question #3? 5. A solution has 189 grams of HNO3 dissolved in 1000 L of water. What is pH?
Tuesday, February 25, 2014 at 12:23pm

Chemistry
Thanks a lot Dr. Bob!
Tuesday, February 25, 2014 at 10:44am

nutrition - science? maybe even chemistry?
.
Tuesday, February 25, 2014 at 9:15am

chemistry
at an equilibrium mixture of PCl5, PCl3, and Cl2 has partial pressures of 217.0 Torr, 13.2 Torr and 13.2 Torr respectively. a quantity of Cl2 is injected into the mixture, and the total pressure jumps to 263.0 Torr (at the moment of mixing). the system then re-equilibrates. ...
Tuesday, February 25, 2014 at 6:42am

Chemistry
I think that your concentrations of Pb and Cl are lower than you think they are. If you were to add 1L of 1M Pb+ to 1L of 1M Cl-, remember that you now have doubled the amount of liquid. You now have 2 L of liquid with 1 mole of Pb+ and 1 mole of Cl- in it. As you add your Cl...
Tuesday, February 25, 2014 at 5:16am

Chemistry
150.248
Tuesday, February 25, 2014 at 12:42am

CHEMISTRY - SCIENCE
mols I2 = grams/molar mass Solve for mols I2. Use density to convert 130 mL propane to grams. m = mols solute/kg solvent
Tuesday, February 25, 2014 at 12:28am

Chemistry
When a blank is used the spectrophotometer is made to read 100% with the blank inserted (you may make it read A = 0 which is the same as 100%T). So if you set the unit to read 100%T (0 Absorbance) with the blank, what will it read if you next insert a dilute Cr solution. We ...
Tuesday, February 25, 2014 at 12:25am

CHEMISTRY - SCIENCE
What is the molality of a solution of 50g of I2 (iodine) dissolved in 130 mL of propane. Propane density .49g/mol.
Tuesday, February 25, 2014 at 12:12am

Chemistry
Why is a blank solution used in absorption spectroscopy? I know it is to nullify the reflection, refraction, and diffraction that occurs, but if the blank solution was a dilute solution rather deionized water, how would the concentration of Cr(VI)in a sample be affected?
Tuesday, February 25, 2014 at 12:08am

Chemistry
Count the electrons and look up the atomic number on the periodic table. But it's an excited atom not in the ground state.
Monday, February 24, 2014 at 11:30pm

Chemistry
What atom is indicated by the following electron configuration. 1s^22s^12p^1 ?
Monday, February 24, 2014 at 11:26pm

chemistry
Here is how you do it if you find that information. delta T = (39.9-normal f.p.) = Kf*m Substitute and solve for m = molality m = mols solute/kg solvent Substitute and solve for mols solute. mols solute = grams solute/molar mass solute. You know mols and grams, solve for molar...
Monday, February 24, 2014 at 11:22pm

chemistry
I don;t know what 81.2 kg/mol means for a Kf. I don't know the normal freezing point of biphenyl.
Monday, February 24, 2014 at 11:15pm

Chemistry
Ca(OH)2 solid in H2O. Saturated solution. Ca(OH)2 + 2HCl ==> CaCl2 + H2O Ca(OH)2 suspension. Saturated solution. Add HCl. The New ionic rxn is 2OH^- + 2H^+ ==> 2H2O. H2O is very weak electrolyte. Rxn goes to completion forming H2O. That reduces the OH^- in solution ...
Monday, February 24, 2014 at 11:12pm

Science: Chemistry - Enthalpy
-128000
Monday, February 24, 2014 at 11:12pm

Chemistry
Some people should not be allowed to help others with chemistry...solids do not have concentrations...therefore doubling the volume would have no effect
Monday, February 24, 2014 at 11:09pm

Chemistry
How does Le Chatelier's principle explain the result you obtained when you add HCL to a suspension of Ca(OH)2 in water? Where the result was, precipitate dissappeared and an increase in temperature resulted.
Monday, February 24, 2014 at 10:51pm

chemistry
Jin? Abby? Use PV = nRT and calculate n to reduce the pressure to that indicated, then n = grams/molar mass. You know n and molar mass, solve for grams.
Monday, February 24, 2014 at 10:46pm

chemistry
Its asking for the molar mass of the unknown, sorry.
Monday, February 24, 2014 at 10:43pm

chemistry
A 33.0-L cylinder contains 481 g O2(g) at 22.5°C. What mass of O2(g) must be released to reduce the pressure in the cylinder to 6.16 atm, assuming the temperature remains constant? Thanks! :D
Monday, February 24, 2014 at 10:35pm

chemistry
Read your question and rephrase it to take care of the errors. You surely don't mean calculate mass. The mass is given. And you don't give the normal freezing point so we don't know delta T. And that 81.2 kg/mol? Kf is usually given in C/m.
Monday, February 24, 2014 at 10:33pm

Chemistry
iytd
Monday, February 24, 2014 at 10:29pm

chemistry
How many mols did yu start with? That's mols NH4NO3 = grams/molar mass Now convert mols NH4NO3 to mols H2O using the coefficients in the balanced equation. Do the same for mol O2 and the same for mols N2. Add mols to find total mols, then use PV = nRT to solve for pressure.
Monday, February 24, 2014 at 10:29pm

chemistry
Suppose that a student calculated Kf of biphenyl to be 81.2C kg/mol. calculate the mass of an unknown if a solution containing 1.64 g of unknown in 18.22 g of biphenyl froze at 39.9 C
Monday, February 24, 2014 at 10:19pm

chemistry
LAST QUESTION: When solid NH4NO3 decomposes, a mixture of gases is obtained: 2 NH4NO3(s)--> 4H2O(g) + O2(g) + 2 N2(g) In an experiment, 5.02 g NH4NO3 decomposes completely in a rigid 5.00-L container. What is the total pressure in the container if the final temperature is ...
Monday, February 24, 2014 at 10:17pm

Chemistry
1s2 2s2 2p6 3s2 3p3 Count the electrons; that's the atomic numbr and you didn't need to write the electron configuration to do that. You can count from the problem. C. Count the p. D.total protons must = total electrons E. Can you find them?
Monday, February 24, 2014 at 10:11pm

Chemistry
2N^2 = ?
Monday, February 24, 2014 at 10:07pm

Chemistry 192
Ni is 1s2 2s2 2p6 3s2 3p6 3d8 4s2 Remove the 2 4s electrons to make the 2+ ion. Now you do Br. Write the neutral atom then add an electron to the outside shell.
Monday, February 24, 2014 at 10:06pm

Chemistry
A neutral atom of an element has 2 electrons with n=1, 8 electrons with n=2, and 5 electrons with n=3. Write its electron configuration and find: A) atomic number B) total number of s electrons C) total number p electrons D) total number of protons E)Paired electrons F)...
Monday, February 24, 2014 at 10:00pm

Chemistry
The Maximum number of electrons that may occupy the third electron shell is A)2 B)8 C)10 D) 18
Monday, February 24, 2014 at 9:57pm

Chemistry 192
Give the electron configuration for the following: A) Ni^2+ B) Br^-
Monday, February 24, 2014 at 9:56pm

chemistry
unk = 10/19.6 = approx 0.5 mL/min He = 10/5.05 = appxox 2 mL/min (2/0.5) = sqrt(M/4) Square both sides. (4/0.25) = M/4 Now solve for M.
Monday, February 24, 2014 at 9:53pm

chemistry
It takes 19.6 mins for a 10.0mL sample of an unknown gas to effuse through a pinhole. A 10.0mL sample of He, required 5.05mins. What is the molar mass of the unknown gas? I got that you have to do : effuse rate of He/Effuse rate of Mx = Square root of (Mx/MHe) but then im ...
Monday, February 24, 2014 at 9:44pm

chemistry
10.0 mL H2O2 x 1.01 g/mL x 0.03 = ? g O2. mols O2 = g/molar mass Then use PV = nRT to solve for volume O2 at the conditions listed.
Monday, February 24, 2014 at 9:30pm

chemistry
This is a limiting ragent problem. I know that because amounts are given for BOTH reactants. When dealing with gases and the T and P remain the same, one can take a short cut ans use volume directly as if volume = mols. It saves a little time. a. Calculate volume butane formed...
Monday, February 24, 2014 at 9:26pm

chemistry
Hydrogen peroxide, H2O2, is used to disinfect contact lenses. What volume of O2, in mL, or O2(g) at 31 degree celsius, and 741mmHg can be liberated from 10.0mL of an aqueous solution containing 3.00% H2O2 by mass? The density of aqueous solution of H2O2 is 1.01g/mL. Thanks! :)
Monday, February 24, 2014 at 9:17pm

Gas Law Chemistry
48,48
Monday, February 24, 2014 at 9:16pm

chemistry
Carbon monoxide, CO and hydrogen, H2, react accordingly: 4CO(g)+9H2(g)-->C4H10(g)+4H2O What volume of the EXCESS REACTANT remains if 17.2L CO and 42.1L H2 are allowed to react? Assume both gases are measured at 711 degree celsius and 1.33atm.
Monday, February 24, 2014 at 9:14pm

chemistry
I don't think so.
Monday, February 24, 2014 at 8:58pm

Chemistry
There may be better, faster. and easier ways to do this but this is a fast write up, too. I can't do flow diagrams on this forum so take what I write and turn it into a flow diagram. Add NaOH (but not a huge excess) to ppt Al, Fe and Ni. Ca is in the filtrate. To the ppt, ...
Monday, February 24, 2014 at 8:55pm

chemistry
you know PV=kT solve for V, then use density = mass/volume
Monday, February 24, 2014 at 8:51pm

chemistry
What is the density of CH4 gas at 32.7 degree celsius and 109kPa? The molar mass of CH4 is 16.042g/mol.
Monday, February 24, 2014 at 8:39pm

Chemistry
How would one go about separating the following substances. It's review for my test. A solution contains Al3+, Ca2+, Fe3+ , and Ni2+ ions. Draw a flow chart that outlines the procedure required to separate this mixture (use the back if you need more room)
Monday, February 24, 2014 at 8:09pm

chemistry
When you touch an object, does the electrons from your hand exchange photons with the object?
Monday, February 24, 2014 at 7:44pm

Chemistry
0.240g = mss Cu + S compound -0.192g = mass Cu --------------- 0.048 g = S added to the Cu %Cu = (mass Cu/mass total)*100 = ? Take a 100 g sample. mols Cu = grams/atomic mass Cu mols S = grams/atomic mass S Find the ratio of Cu to S with the smaller number being 1.00 Post ...
Monday, February 24, 2014 at 6:58pm

chemistry
heat lost by Fe + heat gained by Au = 0 [mass Fe x specific heat Fe x (Tfinal-Tinitial)] + [mass Au x specific heat Au x (Tfinal-Tinitial)] = 0 Solve for Tfinal.
Monday, February 24, 2014 at 6:39pm

CHEMISTRY - SCIENCE
[x g solute/(x g solute + 314 g H2O)]*100 = 42 Solve for x
Monday, February 24, 2014 at 6:17pm

CHEMISTRY - SCIENCE
A solution is 42% NaCl by mass. If 314 mL of H2O was used to create the solution, calculate the , mass of salt that was used.
Monday, February 24, 2014 at 6:08pm

chemistry
A sheet of gold of mass 100g and a teperature of 18.0 degrees is placed flat on a sheet of iron weighing 20g and at a temperature of 55.6 degrees. what is the final temperature of the combined metal.
Monday, February 24, 2014 at 6:04pm

Chemistry
If a 0.192 g sample of copper metal reacts with elemental sulfur to form 0.240 g of the sulfide product, (a) find the percent by mass of copper and sulfur in the product and (b) find the empirical formula of the copper sulfide
Monday, February 24, 2014 at 4:32pm

Pages: <<Prev | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | Next>>

Post a New Question | Current Questions

Homework Help: Science

Search
Members