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April 23, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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chemistry
1.)Calculate the number of moles in 3.50 x 10^21 atoms of silver. Show all work. 2.) Calculate the number of atoms in 2.58 mol antimony. Show all work 3.) Determine the mass of 1.45 mol FePO4. Show all work. 4.) Calculate the number of mol in 6.75 g of NaCl. Show all work. 5...
Sunday, February 9, 2014 at 8:01pm

chemistry
I would go with d but you should know how to do these.
Sunday, February 9, 2014 at 7:34pm

chemistry
AgOH ==> Ag^+ + OH^- Mg(OH)2 ==> Mg^2+ + 2OH^- Ksp Mg(OH)2 = (Mg^2+)(OH^-)^2 Ksp AgOH = (Ag^+)(OH^-) Calculate (OH^-) in a saturated solution of Mg(OH)2. That is .........Mg(OHO2 ==> Mg^2+ + 2OH^- I........solid........0.......0 C........solid........x.......2x E...
Sunday, February 9, 2014 at 7:33pm

AP Chemistry- Equilibrium
See your other post.
Sunday, February 9, 2014 at 7:22pm

AP Chemistry- Equilibrium
MgCl2 + 2NaOH ==> Mg(OH)2 + 2NaCl millimols MgCl2 = 10.0 x 0.18 = 1.8 mmols NaOH = 20.1 x 0.56 = about 11.3 but you should do these more accurately. The remaining steps are approximations too. 1.8 mmols MgCl2 will use 3.6 mmols NaOH and form 1.8 mols Mg(OH)2. The solubility...
Sunday, February 9, 2014 at 7:21pm

chemistry
volume of sphere = (4/3)*pi*r^3 Plug into mass = volume x density I assume you either have or can look up the other information.
Sunday, February 9, 2014 at 7:09pm

Chemistry
Iron(III) selenide It indicates the ion Fe is a Plus 3 valence chromiumIIInitride CrN3 -2, -1, -3 You really ought to be memorizing these. Sr(OH)2
Sunday, February 9, 2014 at 7:06pm

Chemistry
The correct name for the ionic compound Al2Se3 is? I would name this aluminum selenide but some might prefer the name aluminum triselenide. The correct name for the ionic compound Fe2Se3 is? I would name this iron(III) selenide; some may prefer iron(III) triselenide. the Roman...
Sunday, February 9, 2014 at 7:06pm

Chemistry
Hi I was hoping to get some help on this. It's review for my chemistry text on Monday and I would be grateful if someone could help me out. My teacher has been out for two weeks but we still have to know this material. 1. The following data was collected for the reaction ...
Sunday, February 9, 2014 at 7:05pm

chemistry
Assuming that a neutron star has the same density as a neutron, calculate the mass in kilograms of a small piece of a neutron star the size of a spherical pebble with a radius of 0.30mm .
Sunday, February 9, 2014 at 7:03pm

chemistry
I would go with C.
Sunday, February 9, 2014 at 7:02pm

chemistry
the correct formula for the ionic compound containing Tl^3+ and Te^2- ions would be: a. TlTe b. Tl3Te2 c. Tl2Te3 d. Tl2Te
Sunday, February 9, 2014 at 6:54pm

Chemistry
6 separate questions. I have figured out the other 20 questions I am stuck. Please help Thanks The correct name for the ionic compound Al2Se3 is? The correct name for the ionic compound Fe2Se3 is? the Roman numerall III in the name Iron(III)oxice indicates what? Which of the ...
Sunday, February 9, 2014 at 6:49pm

Chemistry
CaCO3 ==> CaO + CO2 mols CaCO3 = 0.01 mol. You get 1 mol CO2 for each mol CaCO3; therefore, you can produce a maximum of 0.01 mol CO2. How many grams is that? g CO2 = mols CO2 x molar mass CO2.
Sunday, February 9, 2014 at 6:49pm

Chemistry
How many moles do you want? That'x M x L = ? Then mols = grams/molar mass.
Sunday, February 9, 2014 at 6:47pm

Chemistry HELP
With 1:2.24 you can't round to 1:2. Multiply by a whole number until you get two whole numbers (or at least to close whole numbers). 1:2.24 2:4.48 3:6.72 4:8.96 which I would round to 4:9 for the formula C4H9. Having done that I don't know what to do except look at ...
Sunday, February 9, 2014 at 6:46pm

AP Chemistry- Equilibrium
If 10.0 mL of 0.18 M MgCl2 are mixed with 20.1 mL of 0.56 M NaOH, what will be the final concentration of Mg2+ in solution when equilibrium is established? Assume the volumes are additive. Ksp = 1.2 ✕ 10-11 for Mg(OH)2.
Sunday, February 9, 2014 at 6:39pm

AP Chemistry- Equilibrium
If 10.0 mL of 0.18 M MgCl2 are mixed with 20.1 mL of 0.56 M NaOH, what will be the final concentration of Mg2+ in solution when equilibrium is established? Assume the volumes are additive. Ksp = 1.2 ✕ 10-11 for Mg(OH)2.
Sunday, February 9, 2014 at 6:39pm

chemistry
What [Ag1+] is required to start precipitation of AgOH from a saturated solution of Mg(OH)2? Ksp = 2.4 ✕ 10-8 for AgOH and Ksp = 2.6 ✕ 10-11 for Mg(OH)2
Sunday, February 9, 2014 at 6:38pm

chemistry
In which of the following pairs of compounds are both members of the pair ionic compounds? Explain a. Pl3 and HBr b. H2S and NCl3 c. LiF and H20 d. LiI and NiO
Sunday, February 9, 2014 at 6:35pm

chemistry
Did you finish your post? I would write for this particular compound Tl2Te3 which I would name thalium(III) telluride
Sunday, February 9, 2014 at 6:20pm

Chemistry
.0042 kg
Sunday, February 9, 2014 at 5:56pm

chemistry
the correct formula for the ionic compound containing Tl^3+ and Te^2- ions would be: Please show. thank you
Sunday, February 9, 2014 at 5:29pm

Chemistry HELP
Complete combustion of 3.30 g of a hydrocarbon produced 10.2 g of CO2 and 4.68 g of H2O. What is the empirical formula for the hydrocarbon? I did the calculation and the ratio comes out to C: 1 H: 2.24 So I thought the answer is CH2 but apparently its wrong. Anyone help..
Sunday, February 9, 2014 at 5:03pm

Chemistry
GIve me the solution
Sunday, February 9, 2014 at 4:56pm

Chemistry
a chemist wants to make 5.5L of a .3M Cacl2 solution. What mass of CaCl2 should the chemist use?
Sunday, February 9, 2014 at 4:35pm

Chemistry
Find the mass of carbon dioxide that can be produced from 0.01 mols of calcium carbonate
Sunday, February 9, 2014 at 4:33pm

chemistry
so you diluted it by half? then it is .5M? I assume the 75ml added was water.
Sunday, February 9, 2014 at 3:49pm

chemistry
A 25.0-ml sample of 1.00M KBr and a 75.0-ml are mixed. The solution is then heated to evaporate water until the total volume is 50.0 ml. What is the Molarity of the KBr in the final solution
Sunday, February 9, 2014 at 3:47pm

chemistry
I need clarification. Group I and II are cations, not anions.
Sunday, February 9, 2014 at 2:15pm

Chemistry
N2 + 3H2 ==> 2NH3 mols NH3 = grams/molar mass = 42800/17 = ? Using the coefficients in the balanced equation, convert mols NH3 to mols H2. Now convert mols H2 to grams. g = molx x molar mass.
Sunday, February 9, 2014 at 2:14pm

Chemistry
b
Sunday, February 9, 2014 at 1:52pm

chemistry
With a halogen X, a metal M forms ionic compounds MX, MX2 and MX3. The lattice energies of the compounds are -1340, -3840 and -7020 kJ/mol, respectively. The ionization energies of the metal are 360 (for M+), 1236 (M2+) and 2990 (M3+) kJ/mol and the sublimation energy is 334 ...
Sunday, February 9, 2014 at 8:50am

Chemistry
The Haber process is used to synthesize ammonia from hydrogen and nitrogen. How much hydrogen is required to produce 42.8 kg of ammonia?
Sunday, February 9, 2014 at 5:34am

chemistry
where can I use Group I and II anions in the field of medicine especially as a medtech student?
Sunday, February 9, 2014 at 2:06am

chemistry
345
Saturday, February 8, 2014 at 10:36pm

chemistry
thank you
Saturday, February 8, 2014 at 10:11pm

chemistry
5.13 g CO2 x (1 mol CO2/44g) x (1 mol C/1 mol CO2) = ? and I don't believe that is 0.117 2.10g H2O x (1 mol H2O/18) x (2 mol H/1 mol H2O) = ?
Saturday, February 8, 2014 at 9:11pm

chemistry
i got for A) 0.117 mol
Saturday, February 8, 2014 at 8:30pm

chemistry
An unknown compound contains only carbon, hydrogen, and oxygen (CxHxOx). Combustion of 3.50G of this compound produced 5.13G of carbon dioxide and 2.10G of water A.How many moles of carbon, , were in the original sample? b. How many moles of hydrogen, , were in the original ...
Saturday, February 8, 2014 at 8:27pm

Chemistry
Oh, sorry. It was supposed to be 50 ml of water instead of 250 ml.
Saturday, February 8, 2014 at 6:29pm

chemistry
C8H18(g) + 25/2(O2)(g) -> 8CO2(g) + 9H2O(g) STANDARD ENTHALPY VALUES (H): 02(g) = 0 kj/mol CO2 (g) = -393.5 kj/mol H20(g) = -241.8 kj/mol H total = -5094 kJ H of C8H18(g) is your unknown, so call that x. use: H of reaction = H of products - H of reactants so, -5094 kJ = [8(...
Saturday, February 8, 2014 at 6:12pm

Chemistry
I wanted to make sure I knew the correct states. Thanks a lot for your help!
Saturday, February 8, 2014 at 5:32pm

Chemistry
In this case yes. If 48% w/v, that means 48g HBr/100 mL solution so 4.6 mL will have 48 g HBr x (4.6 mL/100 mL) = ? g and that gives grams in the volume you want which can be convert to mols by mol = g/molar mass. The problem with w/w is that you have no way of knowing how ...
Saturday, February 8, 2014 at 5:25pm

Chemistry
K3PO4(s) ==> 3K^+(aq) + PO4^3-(aq) I don't know the level of chemistry for you, but I assume you're not expected to know that the PO4^3- ion will hydrolyze in H2O as PO4^3-(aq) + HOH(l) ==> HPO4^2-(aq) + OH^-(aq)
Saturday, February 8, 2014 at 5:18pm

Chemistry
Write the chemical formula and number of ions formed when the following electrolyte dissolves in water. Make sure to include appropriate states. K3PO4 = ??? Any help with this is greatly appreciated!
Saturday, February 8, 2014 at 5:04pm

Chemistry
Thank you. So it is w/v vs w/w that makes the difference
Saturday, February 8, 2014 at 5:01pm

Chemistry
I don't believe it can be done without the density. I think 48% w/v can be done without density but not w/w.
Saturday, February 8, 2014 at 4:45pm

Chemistry
how many moles are in 4.6ml of 48% HBR? The 48% is by weight. I am not given the density this time.
Saturday, February 8, 2014 at 4:29pm

Chemistry (Analytical) followup
I assume this is the CaC2O4 problem. If the pH is reduced to 2, that makes the H^+ MUCH larger (by a factor of 10,000,000 which is really MUCH larger) and the solubility of the CaC2O4 is increased significantly. The reason is that you add a competing reaction (actually two ...
Saturday, February 8, 2014 at 4:01pm

Chemistry
0.656 C
Saturday, February 8, 2014 at 3:59pm

Chemistry (Analytical) followup
Thanks DrBob for answering the question! I was assuming it was something similar to that, but my confusion is that a follow up question is asking what happens to the dissolved Ca2+ if the pH is reduced to 2, so the pH has some effect, but I don't know what.
Saturday, February 8, 2014 at 3:41pm

Chemistry
Is that 10 mL of the 0.2M H3PO4 added to 250 mL H2O to make 260 mL solution? If you titrate the entire solution, which seems unlikely, then you will have H3PO4 ==> NaH2PO4 + H2O mols H3PO4 = 0.010L x 0.2M = 0.002 mols NaOH required = 0.002 since 1 mol H3PO4 = 1 mol NaOH. ...
Saturday, February 8, 2014 at 3:26pm

Chemistry
You want to calculate the molarity of the H2O2. 35% w/w means 35 g H2O2/100 g solution. Since mass = volume x density, then volume = mass/density = 100g/1.14 = about 87.7 mL. mols in 35 g = 35/about 34) = about 1 mol M = mols/L = about 1/0.0877 = ? Then mols in 0.8mL = M x L. ...
Saturday, February 8, 2014 at 3:04pm

Chemistry
I have .8ml of 35% by weight hydrogen peroxide. The hydrogen peroxide density is 1.14 g/ml. how many moles of hydrogen peroxide are there?
Saturday, February 8, 2014 at 2:46pm

Chemistry
A titration involves titrating 0.4 M NaOH into a solution of 0.2 M H3PO4. a.) Calculate the volume of NaOH that will be required to reach the first equivalence point. b.) Calculate the volume of NaOH required to reach the second equivalence point. Other information: 10 ml ...
Saturday, February 8, 2014 at 2:03pm

Chemistry (Analytical)
I'm assuming that at a pH of 9 the H^+ will not increase the solubility over that of a saturated solution of CaC2O4. ............CaC2O4 ==> Ca^2+ + C2O4^2- I............solid......0........0 C............solid......x........x E............solid......x........x Ksp = (Ca...
Saturday, February 8, 2014 at 12:08pm

chemistry
I'm not sure what you mean by a dry solution. Certainly there are many but I don't think any of them apply here. Do you mean 135 mL of 0.120 M NaNO3 in a solvent. Do you want 1 L of solution. You want how many mols? That's M x L = ? = 0.135 x 0.120 = ? Then mol/L...
Saturday, February 8, 2014 at 12:04pm

Chemistry (Analytical)
Solve for the number of grams of Ca2+ ion in a solution prepared by adding 1.00 gram of calcium oxalate (Ksp=1.3x10^-8)powder to 100 mL at pH 9.
Saturday, February 8, 2014 at 12:00pm

Chemistry
14% (that's v/v) means 14 cc ethanol/100 cc wine so 750 cc wine x (14 cc ethanol/100 cc wine) = about 105 cc ethanol. 14 units x (10 cc ethanol/unit) = 140 cc ethanol 140 cc ethanol x (1 bottle/105 cc ethanol) = ? bottles
Saturday, February 8, 2014 at 11:59am

chemistry
How much dry solution would it take to prepare 135 0.120M NaNO3 to a sovent?
Saturday, February 8, 2014 at 11:52am

Chemistry
Alcoholic drinks contain ethanol. 10cm3 of ethanol is called one unit of alcohol. Men are advised to drink a maximum of 21 units of ethanol a week, while women are advised to drink a maximum of 14 units. Wine contains about 14% ethanol by volume. A) a bottle of wine contains ...
Saturday, February 8, 2014 at 10:36am

chemistry
what are the reaction steps of the reaction between ferric chloride with hydrogen at 600 degree celsius
Saturday, February 8, 2014 at 2:50am

chemistry
205 g of HNO3
Friday, February 7, 2014 at 8:10pm

chemistry
88
Friday, February 7, 2014 at 6:53pm

Chemistry
You might get an average out of this. http://en.wikipedia.org/wiki/Carbon-13_N​MR
Friday, February 7, 2014 at 3:10pm

Chemistry
What is the typical 13 c nmr chemical shift range in ppm?
Friday, February 7, 2014 at 3:03pm

college chemistry
kilocalories released when 20.0 g of steam condenses at 100 degrees C. and the liquid cools to 0 degrees C.
Friday, February 7, 2014 at 2:26pm

Chemistry
Thank you! -MC
Friday, February 7, 2014 at 12:36pm

Chemistry
I would go with Br, Si, Cd.
Friday, February 7, 2014 at 12:36pm

Chemistry
Rank Cd, Br, and Si from worst to best conductor of electricity. Is it Br, Cd, Si? Thanks -MC
Friday, February 7, 2014 at 12:33pm

chemistry
So the new pressure is 101 + (100 x 51/10.2) = ? Then P1V1 = P2V2
Friday, February 7, 2014 at 12:30pm

Physics? Chemistry? What??
.
Friday, February 7, 2014 at 10:33am

chemistry
2)Tf = (0.00089 +/- 0.00008) * (13 +/- 2) + (19.627 +/- 0.004) Tf = (0.012 +/- 0.002) + (19.627 +/- 0.004) Tf = 19.639 +/- what value?
Friday, February 7, 2014 at 9:46am

chemistry
Divers know that the pressure exerted buy the water increases about 100kpa with every 10.2 m of depth. This means that at 10.2 m below the surface, the pressure is 201 kpa; at 20.4 m , the pressure is 301 Kpa; and so forth. Given that the volume of a balloon is 3.5L at STP and...
Friday, February 7, 2014 at 8:55am

Chemistry
%Oxygen = (3*16/molar mass KClO3*100 = ? about 39%
Thursday, February 6, 2014 at 10:47pm

Chemistry
It says 8. In a similar experiment Mary Moreorlesss was to determine the loss of weight when a crucible of potassium chlorate was heated to drive off the oxygen. After finishing the experiment she concluded the potassium chlorate contained 24.0% oxygen. Why did miraculous(...
Thursday, February 6, 2014 at 10:25pm

Chemistry
Along those lines, yes. The calculation is complicated by the fact that NaCl ionizes completely into two ions while the dextrose isn't ionized at all. With NaCl you must use pi = i*nRT where i is 2 for NaCl. For dextrose i = 1. So I would calculate M NaCl and M dextrose, ...
Thursday, February 6, 2014 at 10:18pm

Chemistry
what if you were mixing two different solutions? such as .9% of the NaCl solution and a 5% dextrose solution? would you just find the moles of both like the above and add them together? then divide all of it by the L?
Thursday, February 6, 2014 at 10:00pm

Chemistry
You are. mols NaCl = 0.9g/58.44 = ? ?/0.1 = M
Thursday, February 6, 2014 at 9:27pm

Chemistry
q for ice at -20 to ice at 0. q = mass x specific heat ice x delta T (dT = 20). q to melt the ice is q = mass ice x heat fusion. q to heat from zero to 95. q = mass H2O x specific heat H2O x dT and dT = 95. Then sum the q values.
Thursday, February 6, 2014 at 9:24pm

Chemistry
I'm doing something wrong with osmolarity. I have 100 ml of .9% NaCl. So what i did was take the MW (58.44) and divided it by the .9 because it should be grams, then divided that number by .1 (for the liters) but its coming out with a huge number and its not supposed to. I...
Thursday, February 6, 2014 at 9:23pm

Chemistry
See Damon's response above.
Thursday, February 6, 2014 at 9:04pm

Chemistry
pBr2 = ? n = 0.960 R = 0.08206 T = 273 + 1000 = 1273K p = nRT/V = (0.960)*0.08206 x 1273/1 = 100.28 BUT I said that was approx and you should go through it with more accuracy. I would round that to 100. pH2 = (1.28*0.08206 x 1273/1 = 128.49 with the same recommendation. I ...
Thursday, February 6, 2014 at 9:02pm

Chemistry
This is a limiting reagent (LR) problem. I know that because amounts are given for BOTH reactants. 2K | i2 ==> 2kI mols K = grams/molar mass mols I2 = grams/molar mass Using the coefficients in the balanced equation, convert mols K to mols KI. Do the same for mols I2 to ...
Thursday, February 6, 2014 at 8:48pm

Chemistry
Calculate the amount of energy in calories that is needed to melt 45g of ice at -20°C and then increase the temperature to 95°C
Thursday, February 6, 2014 at 8:43pm

Chemistry
how many grams of potassium iodide can be produced by the reaction of 150 grams of iodide and 45.6 grams of potassium?
Thursday, February 6, 2014 at 8:19pm

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...
Thursday, February 6, 2014 at 8:03pm

CHEMISTRY
85.2 - 48 = 37.2 mg of X 4 X atoms for every 10 O atoms 10 * 16 = 160 4 * X = 4x 4x/160 = 37.2/48 4 X = 160 *37.2/48 X = 31 check 31 * 4 = 124 16 *10 =160 124/160 = .775 and 37.2/48 = .775 good
Thursday, February 6, 2014 at 6:19pm

CHEMISTRY
A 85.2-mg sample of the compound X4O10 contains 48.0 mg of oxygen atoms. What is the atomic mass of element X?
Thursday, February 6, 2014 at 6:10pm

Chemistry
hy
Thursday, February 6, 2014 at 5:45pm

Chemistry
A 85.2-mg sample of the compound X4O10 contains 48.0 mg of oxygen atoms. What is the atomic mass of element X?
Thursday, February 6, 2014 at 5:37pm

Chemistry
What exactly is your problem in doing this?
Thursday, February 6, 2014 at 4:27pm

Chemistry
Use the periodic table and predict the number of electrons that will be lost or gained by the following elements as they change into simple ions. Write an equation using elemental symbols, ionic symbols, and electrons to represent each change. a) Ca b) Aluminum c) Fluorine d) ...
Thursday, February 6, 2014 at 4:10pm

Chemistry
52.6
Thursday, February 6, 2014 at 3:48pm

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...
Thursday, February 6, 2014 at 3:48pm

Chemistry?
a
Thursday, February 6, 2014 at 2:33pm

Chemistry?
a
Thursday, February 6, 2014 at 2:33pm

Chemistry needs help
Indicate your specific subject in the "School Subject" box, so those with expertise in the area will respond to the question.
Thursday, February 6, 2014 at 1:09pm

Chemistry
0.038 mol FeCl2 x (1 mol K2Cr2O7/6 mol FeCl2) = mols K2Cr2O7. Then M = mols/L so L = mols/M = Then multiply by 1000 to convert to mL.
Thursday, February 6, 2014 at 12:50pm

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