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April 18, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
In a 1.0 x10-6 M of HNO3 (aq) at 25 degrees celsius identify the relative molar amounts of theses species HNO3- H3O+ OH- NO3- H2O
Friday, February 21, 2014 at 2:51pm

Chemistry 2
A solution of NaOH (aq) contains 8.2 grams of NaOH(s) per 100.0 mL of solution. Calcualte Ph and POH at 25 degrees celsiuis
Friday, February 21, 2014 at 2:30pm

Chemistry
a mixture of 10cm^3 of C5H12 and 0.084g of C12H24 was passed with an excess of oxygen. after cooling to room temperature, the reaidual gas was passed through aqueous potassium hydroxide. what volume was absorbed by the alkali
Friday, February 21, 2014 at 2:25pm

Chemistry 2
Calcualte PH and POh of an aqueous solution that is 0.050 M in HCL and 0.085 M in HBr at 25 degrees C
Friday, February 21, 2014 at 2:23pm

Chemistry
. ' ' ' ; ;;; ; ; ; ; ; ; ; ; ; ;;; ; ; ; ; ; ; ; ; ; ; ; ;
Friday, February 21, 2014 at 1:45pm

Chemistry 2
Calculate Kp for the reaction C(s)+CO2(g)<-->2CO(g) kp=? C(s)+2H2O(g)<--->CO2(g)+2H2 kp1=3.47 H2(g)+CO2(g)<--->H2O(g)+CO(g) kp2=0.735
Friday, February 21, 2014 at 1:30pm

college chemistry
Rubidium metal, Rb, crystallizes in a body-centered cubic arrangement. What is the radius of one atom of Rb, if its density is 1.5320 g/cm3?
Friday, February 21, 2014 at 1:27pm

Chemistry
A+2B--->2C Kc=2.27 2c--->D Kc=0.144 Calculate the equilibrium constant for the reaction D--->A+2B
Friday, February 21, 2014 at 1:18pm

chemistry
Which of the following would make a good semiconductor? aluminum germanium gold concrete
Friday, February 21, 2014 at 1:02pm

Chemistry
Write the K expression. Now, to have K 7.0 (greater than 1.0), must products or reactants be greater or less?
Friday, February 21, 2014 at 12:29pm

Chemistry
Didn't I do one like this for you yesterday. c1v1 = c2v2 c = concn v = volume 5*200 = 2*mL mL = total volume.
Friday, February 21, 2014 at 12:26pm

Chemistry
How much water would I need to add in order to dilute 200mL of a 5 M solution down to 2 M?
Friday, February 21, 2014 at 12:17pm

Chemistry
I tried and didn't get a accurate answer.
Friday, February 21, 2014 at 11:53am

Chemistry
I honestly don't know the teacher have us this worksheet that says percent compostion.
Friday, February 21, 2014 at 11:46am

Chemistry
For the reaction given, the value of the equilibrium of the constant at 400 K is 7.0. Br2(g)+ Cl2(g)=2BrCl(g) Does the: Reaction proceed to the left? Reaction proceed to the right? Partial pressure represent a system in an equation?
Friday, February 21, 2014 at 10:44am

Chemistry
determine the amount of water formed in 4NH3 + 5O2 4NO + 6H2O if 10 g of Oxygen is mixed with 10g nitrigen trihydride in grams
Friday, February 21, 2014 at 10:43am

Chemistry
120.0g of ice is melted, how much energy is absorbed?
Friday, February 21, 2014 at 9:04am

chemistry
How much heat is released when 28.95g of water is frozen?
Friday, February 21, 2014 at 9:04am

chemistry
idont know theb answer
Friday, February 21, 2014 at 8:38am

Chemistry
Your second problem is a limiting reagent (LR) problem. You know it is a LR problem because amounts are given for BOTH reactants. You do these just like simple stoichhiometry problem BUT do it for EACH reagent then take the smaller amount formed as the product formed. Convert ...
Friday, February 21, 2014 at 12:39am

Chemistry
mols AgNO3 = M x L = ? Using the coefficients in the balanced equation, convert mols AgNO3 to mols NaCl. Now convert mols NaCl to grams. g = mols x molar mass.
Friday, February 21, 2014 at 12:32am

Chemistry
l
Friday, February 21, 2014 at 12:31am

Chemistry
168
Friday, February 21, 2014 at 12:15am

Chemistry
2.5 mol Zn and 8.75 mol HCl react according to the equation Zn + 2 HCl −→ ZnCl2 + H2 . Calculate the amount in moles of ZnCl2 formed. Answer in units of mol
Friday, February 21, 2014 at 12:12am

Chemistry
AgNO3 + NaCl → AgCl + NaNO3 . How many grams of NaCl would be required to react with 446 mL of 0.211 M AgNO3 solution? Answer in units of grams
Friday, February 21, 2014 at 12:10am

chemistry
mols NH3 = grams/molar mass A. Convert mols NH3 to mols F2 using the coefficients the balanced equation. ?mols NH3 x (5 mols F2/2 mol NH3) = ? mols F2. Then convert mols to grams. g F2 = mols F2 x molar mass F2. B. and C. are done the same way.
Thursday, February 20, 2014 at 11:17pm

chemistry
CuCl2 + 2NaNO3 ==> 2NaCl + Cu(NO3)2 mols CuCl2 = grams/molar mass Using the coefficients in the balancaed equation,convert mols CuCl2 to mols NaCl formed. Convert mols NaCl formed to grams. g = mols x molar mass. This is the theoretical yield (TY). The acuual yield (AY) is ...
Thursday, February 20, 2014 at 11:14pm

Chemistry
To keep the can from exploding due to increased pressure from the heating.
Thursday, February 20, 2014 at 11:12pm

Chemistry
Can't draw pictures. 6.0M x 500 mL = 2M x ?mL ? mL is the total volume needed.
Thursday, February 20, 2014 at 11:10pm

AP Chemistry
See your later post above.
Thursday, February 20, 2014 at 11:09pm

Chemistry
What's the problem?
Thursday, February 20, 2014 at 11:08pm

to abdul---chemistry
You should post your own question from the top of the page instead of piggy backing onto another.
Thursday, February 20, 2014 at 11:07pm

chemistry
q to melt ice @ 0C to liquid H2O @ 0C. q to move T from zero C to 100 C q to change liquid at 100 to steam at 100.
Thursday, February 20, 2014 at 11:06pm

Chemistry
You must take HF into consideration during the calculation. The whole point of these problems is to show you that BaF2 has a certain solubility in neutral solution. As the solution becomes more and more acid the formation of HF becomes more (because HF is a weak acid); that ...
Thursday, February 20, 2014 at 11:04pm

Chemistry
py + HBr ==> PyH + Br^- You know how many mols pyridine you started with. That's M x L = ? Now take M x L of the titrant to give yo mols HBr added. Since the reaction is 1:1 you know 1 mol HBr neutralizes 1 mol pyridine. Subtract mols py-mol HBr to see which is in ...
Thursday, February 20, 2014 at 11:01pm

Chemistry
No. You need to brush up on the difference between precision and accuracy. The students obtained 7.32 for a 2 g weight. That isn't very accurate at all or they would have obtained 2g wouldn't they? However. all of them obtained the same value of 7.32 so the precision ...
Thursday, February 20, 2014 at 10:52pm

chemistry
THANK YOUUU!
Thursday, February 20, 2014 at 10:51pm

Chemistry
.........NH4^+ + H2O ==> NH3 + H3O^+ I........1E-3.............0.....0 C.........-x..............x......x E.......1E-3-x............x......x Ka for NH4^+ = (Kw/Kb for NH3) = (x)(x)/(0/001-x) Solve for x = (H3O^+). Then (H3O^+)(OH^-) = Kw = 1E-14 and solve for OH^-
Thursday, February 20, 2014 at 10:47pm

chemistry
What is the percent yield of NaCl if 31.0 g of CuCl2 reacts with excess NaNO3 to produce 21.2 g of NaCl?
Thursday, February 20, 2014 at 10:43pm

additional---AP Chemistry
After (SO2) in M, then mol = M x L Then mols = grams/molar mass. Solve for grams.
Thursday, February 20, 2014 at 10:43pm

AP Chemistry
You need to work out the concns. (SO3) = (1.11g/molar mass SO3)/2L = approx 0.007M but you need to do it more accurately as well as calculations that follow. They are estimates also. (O2) = 1.06/32/2L = approx 0.0015M Kc = (SO3)^2/(SO2)^2(O2) Substitute Kc and concns SO3 and ...
Thursday, February 20, 2014 at 10:42pm

Chemistry
Aerosol cans contain com- pressed gases that, when released, help propel the contents out of the can. Why is it important to keep aerosol cans from overheating?
Thursday, February 20, 2014 at 10:39pm

Chemistry help
1/wavelength = R(1/1 - 1/x^2) wavelength = 93.77E-9 m Solve for x = where the electron has been promoted. Then 1/wavelength = R(1/y^2 - 1/x^2) x is the value from the first part of the problem. y is the new level where the electrons finishes its journey. R = Rydberg constant...
Thursday, February 20, 2014 at 10:34pm

chemistry
mols HCl = M x L = ? mols NaOH = mols HCl Then M NaOH = mols NaOH/L NaOH
Thursday, February 20, 2014 at 10:27pm

chemistry
The reaction of fluorine with ammonia produces dinitrogen tetra fluoride and hydrogen fluorida. 5F2(g)+2NH(g)---> N2F4(g)+6HF(g) A. If you have 66.6gNH3, how many grams of F2 are required for a complete reaction? B. how many grams of NH3 are required to produce 4.65g HFCS? ...
Thursday, February 20, 2014 at 10:21pm

Chemistry
Please help me. :(
Thursday, February 20, 2014 at 9:40pm

chemistry
(a) The measured pH of a 0.200 M HBr solution at 25°C is 0.806. Calculate the activity coefficient for H . (b) The measured pH of a 0.200 M HNO3 solution at the same temperature is 0.822. Calculate the activity coefficient for H in this solution.
Thursday, February 20, 2014 at 9:38pm

chemistry
!@#$%^&
Thursday, February 20, 2014 at 9:11pm

chemistry
What volume of 1.00 M NaOH would be required to neutralize 77.4 mL of 5.4 M HCl? Round to two places after the decimal point and keep it in mL
Thursday, February 20, 2014 at 8:47pm

Chemistry help
A ground state hydrogen atom absorbs a photon of light having a wavelength of 93.77 nm. It then gives off a photon having a wavelength of 94 nm. What is the final state of the hydrogen atom?
Thursday, February 20, 2014 at 8:43pm

AP Chemistry
For 2 SO2(g) + O2(g) equilibrium reaction arrow 2SO3(g), Kp = 3.0 104 at 700. K. In a 2.00-L vessel the equilibrium mixture contains 1.11 g of SO3 and 0.106 g of O2. How many grams of SO2 are in the vessel
Thursday, February 20, 2014 at 8:36pm

Chemistry
How do you find the [OH-] of a 1x10^-3 M solution of NH4Cl?
Thursday, February 20, 2014 at 8:28pm

Bio Chemistry
There are two main ways in which molecules are transported into and out of cells - active transport and passive transport. Which of the following statements is true of passive transport?
Thursday, February 20, 2014 at 8:21pm

chemistry
idontknow
Thursday, February 20, 2014 at 8:07pm

Chemistry
Is it that the three different people weighed something of 2.00g and got the readings of 7.32 g for the weight? So, in that case, would the answer be A?
Thursday, February 20, 2014 at 8:03pm

Chemistry
Three people weigh on a standard mass of 2.00 g on the same balance. Each person obtains a reading of 7.32 for the mass of the standard. These results imply that the balance that was used is ___________. a) neither accurate nor precise b) accurate c) precise d) accurate and ...
Thursday, February 20, 2014 at 8:01pm

chemistry
When a mixture of 13.0g of acetylene (C2H2) and 13.0g of oxygen gas is ignited, the resultant combustion reaction produces carbon dioxide and water. What is the limiting reactant? any helper
Thursday, February 20, 2014 at 7:52pm

Chemistry
1. Calculate the pH for each of the following cases in the titration of 25.0 mL of 0.240 M pyridine, C5H5N(aq) with 0.240 M HBr(aq): (a) before addition of any HBr (b) after addition of 12.5 mL of HBr (c) after addition of 22.0 mL of HBr (d) after addition of 25.0 mL of HBr (e...
Thursday, February 20, 2014 at 7:06pm

Chemistry
Consider the two equilibria: BaF2=Ba2+ + 2F- Ksp=1.7x10^(-6) F- + H20=HF + OH- Kb=2.9x10^(-11) Determine the solubility of BaF2 at pH=5? What I'm mostly confused about is how to determine if F- is dominant or if you have to take HF into account while doing your calculations.
Thursday, February 20, 2014 at 6:50pm

chemistry
How many enthalpy changes (ÄH’s) would be required to calculate the total enthalpy change when ice at 0.0oC is turned to steam at 100.0oC?
Thursday, February 20, 2014 at 6:40pm

Chemistry
Zn is almost always 2 as its placement in the periodic table would suggest. Same for Sc at +3. All of the others are variable. At least ONE valence will be the period; for example, Mn has bunches of numbers but +7 is one of them. Cr has several but at least one of them is +6. ...
Thursday, February 20, 2014 at 6:25pm

Chemistry
Christian Brothers Brandy (80%, 1.7 L) what do I do with this problem it's a percent compostion work sheet
Thursday, February 20, 2014 at 6:24pm

Chemistry
3.6 x [750/(750-150)]= ?
Thursday, February 20, 2014 at 6:20pm

AP Chemistry
For 2 SO2(g) + O2(g) equilibrium reaction arrow 2SO3(g), Kp = 3.0 104 at 700. K. In a 2.00-L vessel the equilibrium mixture contains 1.11 g of SO3 and 0.106 g of O2. How many grams of SO2 are in the vessel
Thursday, February 20, 2014 at 6:19pm

chemistry
2.4 x (250/750) = ?
Thursday, February 20, 2014 at 6:18pm

Chemistry
I have 500 mL of a 6.0 M solution that I want diluted down to 2 M. How many mL of water should I add to the solutiion. " FOR EVERY PROBLEM YOU MUST DRAW A PICUTRE"
Thursday, February 20, 2014 at 6:18pm

chemistry
1/3 of the original concentration
Thursday, February 20, 2014 at 6:09pm

Chemistry
If I leve 750 mL of 3.6 sodium chloride solution uncoverd and 150 mL of the solvent evaporates overnight, what is the new solution concentration?
Thursday, February 20, 2014 at 6:08pm

chemistry
if I dilute 250 of mL of 2.4 M lithium hydroxide solution so that it's new volume is 750 mL, what is the concentration of the solution? 
Thursday, February 20, 2014 at 6:06pm

Chemistry
how do i figure out the valences for elements in the transition elements section in the periodic table of elements (i need it for doing nomenclature) and how do i figure out the valences if i don't have the periodic table of elements examples: Zn Cu Ni Co Fe Mn Cr V Ti Sc
Thursday, February 20, 2014 at 5:25pm

Chemistry
after using the dilution formula M1V1=M2V2, i got .6L of water
Thursday, February 20, 2014 at 4:40pm

chemistry
a. NaBr - nearly neutral b. K2SO3 - basic c. NH4NO2 - acidic d. Cr(NO3)3 - acidic
Thursday, February 20, 2014 at 4:22pm

Chemistry
Write the total and net ionic equations for the following molecular reaction: HgNO3 (aq) + NaCl (aq) -> HgCl (s) + 2 NaNO3 (aq)
Thursday, February 20, 2014 at 2:17pm

chemistry
An aqueous solution of HCl has a concentration of .160m and a density of 1.0691 g/mL. What is the concentration of HCl as molarity?
Thursday, February 20, 2014 at 2:12pm

Chemistry
Assign oxidation numbers to each individual element in the following reaction and identify the oxidizing and reducing agents. 2 Zn S + 3 O2 -> 2 S O2 + 2 Zn O Ox#: Zn=+2 S=-2 O=-2 -> S=+2 O=-2 Zn=+2 O=2 Is that correct? I'm not sure how to identify the oxidizing and ...
Thursday, February 20, 2014 at 2:11pm

Chemistry
A0 2.95 cm3
Thursday, February 20, 2014 at 12:26pm

chemistry
A
Thursday, February 20, 2014 at 12:15pm

Chemistry
HCl is a strong acid; i.e., it ionizes 100%. Same for HBr. So the combined M in the solution is 0.5+0.085. pH = -log(H^+), then pH + pOH = pKw = 14.
Thursday, February 20, 2014 at 11:42am

Chemistry
Calculate the Ph and POH of an aqueous soltuion that is 0.500 M in HCl(aq) and 0.085 M in HBr (aq) at 25 degrees C.
Thursday, February 20, 2014 at 10:54am

Chemistry
See your post above.
Thursday, February 20, 2014 at 9:35am

Chemistry
I agree with the last answer.
Thursday, February 20, 2014 at 9:34am

Chemistry
Your mistake is you didn't take into account the van't Hoff factor, i. The equation is delta T = i*Kf*m is for CsX is 2.
Thursday, February 20, 2014 at 9:29am

Chemistry
Look at the equation. The equation tells you 1 mol CaO reacts with 1 mol H2O to yield 1 mol Ca(OH)2.
Thursday, February 20, 2014 at 9:23am

Chemistry
Given the equation CaO + H2O = Ca(OH)2 if you start with 1.86 moles of CaO, how many moles of Ca(OH)2 will result?
Thursday, February 20, 2014 at 9:11am

Chemistry
A compound is known to be a cesium halide, CsX. If 3.00 grams of the salt is dissolved in exactly 100.0 grams of water, the solution freezes at -0.735°C. What is the chemical formula for the salt? i know it would be -0.735= -1.86 * m m= 3g/ X g/mol/kg solvent however the ...
Thursday, February 20, 2014 at 9:00am

Chemistry
replace the 7.77 with 9.23 answer in end in 5.20 x 10^-6
Thursday, February 20, 2014 at 2:46am

Chemistry
Pb(NO3)2 => Pb2+ + 2 NO3- [Pb2+] = [Pb(NO3)2] = 7.77 mM = 7.77 x 10-3 M Pb(IO3)2 <=> Pb2+ + 2 IO3- Ksp = [Pb2+][IO3-]2 = 2.5 x 10-13 7.77 x 10-3 x [IO3-]2 = 2.5 x 10-13 [IO3-] = 5.67 x 10-6 M ˜ 5.7 x 10-6 M
Thursday, February 20, 2014 at 2:44am

Chemistry
Calculate the concentration of IO3– in a 9.23 mM Pb(NO3)2 solution saturated with Pb(IO3)2. The Ksp of Pb(IO3)2 is 2.5 × 10-13. Assume that Pb(IO3)2 is a negligible source of Pb2 compared to Pb(NO3)2.
Thursday, February 20, 2014 at 2:16am

Chemistry
A compound is known to be a cesium halide, CsX. If 3.00 grams of the salt is dissolved in exactly 100.0 grams of water, the solution freezes at -0.735°C. What is the chemical formula for the salt?
Thursday, February 20, 2014 at 1:52am

College Chemistry
See this. http://www.jiskha.com/display.cgi?id=139​2734601
Wednesday, February 19, 2014 at 10:54pm

College Chemistry
J = mass x specific heat x (Tfinal-Tinitial)
Wednesday, February 19, 2014 at 10:53pm

Chemistry
E = hc/wavelength Substitute wavelength and solve for E = ? J/photon. 7 kJ/s/m^2 x 8.40 cm^2 x *(1 m/100 cm)^2 x (1 kJ/1000J) = Joules striking 8.40 cm^2 area. Then ? J/photon x # photons = J striking 8.40 cm^21 area. Solve for # photons.
Wednesday, February 19, 2014 at 10:45pm

Chemistry
At noon on a clear day, sunlight reaches the earth\'s surface at Madison, Wisconsin, with an average power of approximately 7.00 kJ·s–1·m–2. If the sunlight consists of photons with an average wavelength of 510.0 nm, how many photons strike a 8.40 ...
Wednesday, February 19, 2014 at 10:33pm

chemistry 112
For an 80% yield you will need 1.6 mols SO3. .........2SO2 + O2 ==> 2SO3 I........2 mols..2.......0 C........-2x.....-x......2x E.......2-2x.....2-x.....2x Then an 80% yield gives SO3 = 1.6 mol; therefore, 1.6 = 2x and x = 0.8 Solve for 2-2x = 0.4 mol SO2 2-x = 1.2 mols O2 ...
Wednesday, February 19, 2014 at 9:23pm

Chemistry
Given an unknown mixture consisting of two or more substances, explain how we could determine whether that mixture is a true solution, a colloid, or a suspension
Wednesday, February 19, 2014 at 8:36pm

College Chemistry
If a 375 mL sample of water was cooled from 37.5°C to 0°C, how much heat was lost (in joules)
Wednesday, February 19, 2014 at 7:44pm

College Chemistry
A 150.0 mL sample of a 1.50 M solution of CuSO4 is mixed with a 150.0 mL sample of 3.00 M KOH in a coffee cup calorimeter. The temperature of both solutions and the calorimeter was 25.2°C before mixing and 31.3°C after mixing. The heat capacity of the calorimeter is ...
Wednesday, February 19, 2014 at 7:43pm

chemistry 112
the formation of SO3 from so2 and o2 is an intermediate step in the manufacture of sulfuric acid, and it is also responsible for the acid rain phenomenon. the equilibrium constant Kp for the reaction is 0.13 at 830 degree celcius. in one experiment, 2.00 mol so2 and 2.00 mol ...
Wednesday, February 19, 2014 at 7:15pm

Chemistry; Stoichiometry
70.6
Wednesday, February 19, 2014 at 6:55pm

chemistry
Pick any convenient mass, say 100 g, then mass = volume x density Substitute and see which has the larger voluem.
Wednesday, February 19, 2014 at 6:30pm

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