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April 19, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
Compare the physical and chemical properties of acids and bases.
Tuesday, March 4, 2014 at 7:31pm

Chemistry
if 25.0 mL of 15M nitric acid is diluted to 125 mL, what is the concentration of the new solution? i got 3M but i dont think its right
Tuesday, March 4, 2014 at 7:07pm

Chemistry
You are welcome :)
Tuesday, March 4, 2014 at 6:50pm

Chemistry
if 25.0 mL of 15M nitric acid is diluted to 125 mL, what is the concentration of the new solution? i got 3M but i dont think its right
Tuesday, March 4, 2014 at 6:37pm

Chemistry
ohh okay now i understand. thank you
Tuesday, March 4, 2014 at 6:27pm

Chemistry
well, if I had one liter of the final stuff I would have 6 mols of H2SO4 in it so in 250 mL I need 6/4 or 1.5 mols H2SO4 so the real question is: What volume of 18M H2SO4 contains 1.5 mols of H2SO4 well there are 18 in a liter so I need 1.5/18 liter =.08333...... Liter which ...
Tuesday, March 4, 2014 at 6:25pm

Chemistry
so v would be 83mL?
Tuesday, March 4, 2014 at 6:22pm

Chemistry
Use the dilution formula of c1v1 = c2v2 18M*vmL = 6M*250mL v = ?mL.
Tuesday, March 4, 2014 at 6:20pm

Chemistry
m = 4 mol/kg = 4 delta T = Kb*m
Tuesday, March 4, 2014 at 6:18pm

Chemistry
what volume of concentrated 18M H2SO4 is required to prepare 250mL of a 6.0M solution? how would you solve this problem? i know it has something to do with the molarity formula but no idea how to apply it
Tuesday, March 4, 2014 at 6:17pm

College Chemistry.
Reverse eqn 1 and add to 3x eqn 2. That gives you the equation you want. Then for dH, change the sign of eqn 1 and add to 3x dH for eqn 2. By the way, you can't get what you want UNLESS you balance that equation you want. 2H2S + 3O2 ==> 2SO2 + 2H2O
Tuesday, March 4, 2014 at 5:54pm

Chemistry
I am having the same issue
Tuesday, March 4, 2014 at 5:53pm

chemistry 2
You want 800 x 0.69 = approx (you need to do it) 552 mmols total. I may have different K values than you. I will use 7.20 for pK2. 7.6 = 7.2 + log (base)/(acid) Solve for b/a and I get approx b/a = 2.5 (in millimols--not concn) a + b = 552 (in millimols). Solve these two ...
Tuesday, March 4, 2014 at 5:32pm

AP Chemistry
acidic, because the cation hydrolyzes to a greater extent than the anion.
Tuesday, March 4, 2014 at 4:25pm

chemistry 2
You are instructed to create 800. mL of a 0.69 M phosphate buffer with a pH of 7.6. You have phosphoric acid and the sodium salts NaH2PO4, Na2HPO4, and Na3PO4 available. what is the molarity needed for the acid component of the buffer?What is the molarity needed for the base ...
Tuesday, March 4, 2014 at 3:36pm

College Chemistry.
During volcanic eruptions, hydrogen sulfide gas is released and is oxidized by the oxygen in the air yielding sulfur dioxide gas and water vapour. Calculate the standard enthalpy change for this reaction given the following: 3S(rhombic) + 2H2O(g) → 2H2S(g) + SO2(g) Δ...
Tuesday, March 4, 2014 at 2:23pm

Chemistry
How much would the boiling point of water increase if 4 mol of sugar were added to 1 kg of water (Kb=0.51C/(mol/kg)for water and i=1 for sugar)?
Tuesday, March 4, 2014 at 1:15pm

AP Chemistry
Rank the following in terms of increasing ox- ide acidity. 1. Na2O, CO2, NO2 2. CO2, NO2, Na2O 3. NO2, CO2, Na2O 4. CO2, Na2O, NO2
Tuesday, March 4, 2014 at 12:46pm

chemistry- transferring energy
.
Tuesday, March 4, 2014 at 12:11pm

Chemistry?

Tuesday, March 4, 2014 at 7:35am

Chemistry Help Please!!!
Boric acid, H3 BO3, is a triprotic acid that dissociates in three reactions. The first dissociation step is: H3BO3 ⇌ H+ + H2BO3, Ka1 = 7.3 x 1010; the second dissociation step is: H2BO3 ⇌ H+ + HBO32, Ka2 = 1.8 x 1013; and the...
Tuesday, March 4, 2014 at 6:49am

Chemistry Need Help!
The limiting reagent is Naphthalene, which means that the moles of NitroNapthalene will equal the moles of Napthalene. Using your calculations, but with two extra-significant figures, moles of Napthalene=moles of NitroNapthalene. 0.02341 moles of Napthalene=0.02341 moles of ...
Tuesday, March 4, 2014 at 2:52am

Chemistry
Partial pressure=(moles of Ar/total moles of gas mixture)*total pressure Partial pressure of Ar=(0.48mol/1.42mol)*1.68 atm ****Answer contains three significant figures.
Tuesday, March 4, 2014 at 2:42am

Chemistry
A mixture of gases is made up 0.48 mol of Ar and 0.94 mol of N2 with a total pressure of 1.68 atm. What is the partial pressure of Ar?
Tuesday, March 4, 2014 at 1:39am

Chemistry Need Help!
Okay, the reaction is this: Naphthalene + HNO3 ---> NitroNapthalene The limiting reagent is Naphthalene The excess is the nitric acid The equation is 1:1 balanced as far as I know 3 g of Nap used in the experiment x 1mol/128.17 g/mol = .023 mol Nap 12.69 g used in the ...
Tuesday, March 4, 2014 at 12:10am

Chemistry
Divide the titration curve into 4 parts. a. beginning b. between beginning and eq pt. c. eq pt d. after eq pt. First, determine mL to eq pt. mLacid x M aci = mL base x M base and that determination tells you how to divide into the four part. a.......... HClO ==> H^+ + ClO...
Tuesday, March 4, 2014 at 12:08am

Chemistry
Calculate the pH for each of the following cases in the titration of 50.0 mL of 0.240 M HClO(aq) with 0.240 M KOH(aq). The ionization constant for HClO can be found here.
Monday, March 3, 2014 at 11:37pm

AP Chemistry
I don't know the Ka values but I suspect Al(NO3)3; however I looked up the Ka values and Fe is about 10^-3 and Al is about 10^-5 so Fe(NO3)3 is a sronger acid than Al(NO3)3.
Monday, March 3, 2014 at 11:27pm

AP Chemistry
mmols HCl = 252 mL x 2.5M = about 630 mmols Ba(OH)2 = 343 x 2.8 = about 960 but you should confirm all of the calculations Some are estimates. 2HCl + Ba(OH)2 ==> BaCl2 + 2H2O First, which is the limiting reagent (LR) Convert mmols HCl to mmols BaCl2. That's 630 x (1 mol...
Monday, March 3, 2014 at 11:13pm

AP Chemistry
Which of the following salts is the most acidic in aqueous solutions? 1. KBr 2. NaI 3. Al(NO3)3 4. BaCl2 5. AgNO3 6. Fe(NO3)2 7. Pb(NO3)2
Monday, March 3, 2014 at 10:47pm

AP Chemistry
If 252mL of 2.5molar HCl solution is added to 343 mL of 2.8 molar Ba(OH)2 solution, what will be the molarity of BaCl2 in the resulting solution?
Monday, March 3, 2014 at 10:28pm

AP chemistry
KOH
Monday, March 3, 2014 at 9:33pm

Chemistry
4NH3 + 3O2 ==> 2N2 + 6H2O mols NH3 = grams/molar mass = ? mols O2 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols NH3 to mols H2O. Do the same for mols O2 to mols H2O. It is likely that these two values will not agree which means one of ...
Monday, March 3, 2014 at 9:12pm

chemistry
What equilibrium?
Monday, March 3, 2014 at 9:03pm

Physical Chemistry
m
Monday, March 3, 2014 at 8:37pm

Chemistry
ha ha ha ha ha
Monday, March 3, 2014 at 8:22pm

Chemistry
144 g s8
Monday, March 3, 2014 at 8:21pm

Physical Chemistry
L
Monday, March 3, 2014 at 8:03pm

chemistry
How would applying an external pressure on the following equilibrium affects the distribution of iodide between the polar (aqueous) and non polar (varsol)
Monday, March 3, 2014 at 7:56pm

Chemistry
a mixture of 34.0g of ammonia and 50.0g of elemental oxygen react to form elemental nitrogen and water. Please write a balanced chemical equation for this reaction. Find the theoretical yield of water in grams and give the amount of excess reactant in grams
Monday, March 3, 2014 at 7:22pm

Chemistry
Use PV = nRT. Plug in the numbers and turn the crank.
Monday, March 3, 2014 at 7:20pm

Chemistry 2
It's what I have above. (1/A) - (1/Ao) = kt. You know k now, the variables are A, Ao (not really a variable I guess) and t. Solve for the missing one.
Monday, March 3, 2014 at 7:18pm

chemistry
can you not help me?
Monday, March 3, 2014 at 7:16pm

chemistry
I suggest that if you are this lost that you get a tutor. Don't wait.
Monday, March 3, 2014 at 7:14pm

Chemistry
What would be the volume of 5.0 moles of gas at STP? Can you explain how to do it please?
Monday, March 3, 2014 at 7:12pm

Chemistry:Important!!!!!!!
volumeacid*Normality acid=volumebase*normality base 20.00*Mconc*2 = 39.13*.1061 solve for Mconce, the molarity of the H2SO4
Monday, March 3, 2014 at 6:40pm

chemistry
chemistry is my weak subject hence why i am on here to get help. I have online questions that need answering in a day and im stuck that's the truth. I have to fnd someone that I might have to pay then looks like it... :(
Monday, March 3, 2014 at 6:34pm

Chemistry:Important!!!!!!!
20.00 mL of a H2SO4 solution with an unknown concentration was titrated to a phenolphthalein endpoint with 39.13 mL of a 0.1061 M NaOH solution. What is the concentration of the H2SO4 solution?
Monday, March 3, 2014 at 6:32pm

chemistry
You won't get a clue, either, unless you try. I assume you are just trying to get answers and you're not trying to understand how to do them. Most of us volunteers on this board will go way out of our way to help but help is what we give, not freebie answer all day long.
Monday, March 3, 2014 at 6:29pm

Chemistry 2
ok i got that now thank you. how will i find the answer for the blanks in the time? is there a formula for it?
Monday, March 3, 2014 at 6:27pm

Chemistry 2
ok thank you, whats the formula to find the time of the missing blanks in the question?
Monday, March 3, 2014 at 6:22pm

chemistry
I really don't have a clue
Monday, March 3, 2014 at 6:21pm

chemistry
it's not duplicate they are all different questions but similar
Monday, March 3, 2014 at 6:20pm

chemistry
Step 1. Pick out M x L. That's in the problem. M is 0.561; L is 0.046 L. M x L = ? you can do on your calculator. Step 2. grams = mols x molar mass You have mols from the calculator. Multiply that by the molar mass of CoO. You can calculate that from the periodic table. Co...
Monday, March 3, 2014 at 6:19pm

chemistry
Duplicate post.
Monday, March 3, 2014 at 6:14pm

chemistry
See your post above.
Monday, March 3, 2014 at 6:14pm

chemistry
Oxidation is the loss of electrons Reduction is the gain of electrons. The substance oxidized is the reducing agent. The substance reduced is the oxidizing agent. Here are some hints: Pb is +4 on the left and +2 on the right. Cr is +3 on the left and +6 on the right.
Monday, March 3, 2014 at 6:13pm

Chemistry 2
ok thank you, exactly what i needed to know .
Monday, March 3, 2014 at 6:12pm

Chemistry 2
This is a first order reaction and will be answered by using Damon's answer to the second order question.
Monday, March 3, 2014 at 6:10pm

chemistry
ClO^-(aq) + H^+(aq) --> HClO(aq)
Monday, March 3, 2014 at 6:09pm

chemistry
i dont know much about chemitry thats why its confusing I don't know how to calculate them
Monday, March 3, 2014 at 6:08pm

chemistry
Co^2+(aq) + CO3^2-(aq) ==> CoCO3(s)
Monday, March 3, 2014 at 6:07pm

chemistry
3PbO2 + 2Cr3++ 2H2O3Pb2+ + 2CrO42-+ 4H+ In the above redox reaction, use oxidation numbers to identify the element oxidized, the element reduced, the oxidizing agent and the reducing agent. 1.name of the element oxidized: 2.name of the element reduced: 3.formula of the ...
Monday, March 3, 2014 at 6:06pm

chemistry
What's the problem? Those four steps will work almost any stoichiometry problem. I won't do the problem for you but I'll help you through it if you explain what you don't understand.
Monday, March 3, 2014 at 6:05pm

chemistry
SO42- + HAsO2+ 2H+H3AsO4 + SO2 In the above redox reaction, use oxidation numbers to identify the element oxidized, the element reduced, the oxidizing agent and the reducing agent. 1. name of the element oxidized: 2. name of the element reduced: 3. formula of the oxidizing ...
Monday, March 3, 2014 at 6:03pm

chemistry
What is confusing about this? And I suggest you pick any name and stick to it. It helps us help you if you do that. For this problem all you need is two steps. M x L = mols and mol x molar mass = grams.
Monday, March 3, 2014 at 6:03pm

Chemistry 2
IVan, the first order reaction done exactly the way Damon worked that problem for you earlier. However, I don't believe that answer was right for a second order reaction. So plug that answer in for this problem and I posted what I think is a correction at the earlier post.
Monday, March 3, 2014 at 6:01pm

chemistry
3PbO2 + 2Cr3++ 2H2O3Pb2+ + 2CrO42-+ 4H+ 1. In the above reaction, the oxidation state of chromium changes from (answer) to (answer). 2. How many electrons are transferred in the reaction?
Monday, March 3, 2014 at 6:01pm

chemistry
SO42- + HAsO2+ 2H+H3AsO4 + SO2 1. In the above reaction, the oxidation state of sulfur changes from (Answer) to (Answer) 2. How many electrons are transferred in the reaction?
Monday, March 3, 2014 at 5:59pm

check this out---Chemistry 2
I believe Damon has worked this as a first order reaction but the problem says it is a second order equation. I think it should be as follows: (1/A) - (1/Ao) = kt (1/5) - (1/20) = 40k 0.2-0.05 = 40k and k = 0.15/40 = 0.00375 and not 0.03466. I assume you can do the remainder ...
Monday, March 3, 2014 at 5:57pm

chemistry
sorry i am stuck on many questions thats why used diff names. i need help and be grateful if u can help but most questions I dont know how to work it out.
Monday, March 3, 2014 at 5:47pm

Chemistry 2
For the fist order reaction A <-> B, calculate the t1/2(half life) and k(rate constant) and also fill in the blanks. A-Concetration t-time 20 0 10 ? 5 40 sec 3 ? ? 500 sec t1/2=? k=?
Monday, March 3, 2014 at 5:40pm

chemistry
i really don't have a clue
Monday, March 3, 2014 at 5:38pm

chemistry
how many grams is that?
Monday, March 3, 2014 at 5:34pm

AP Chemistry
2HCl + Ca(OH)2 ==> CaCl2 + 2H2O pH 3.5 means (HCl) = 3.16E-4 but you should confirm and be more accurate. mols Ca(OH)2 = 2*mols HCl M Ca(OH)2 = mols Ca(OH)2/L Ca(OH)2
Monday, March 3, 2014 at 5:05pm

chemistry
Co(NO3)2 ==> Co(OH)2 --> CoO mols Co(NO3)2 = M x L = ? mols CoO = mols Co(OH)2 = mols Co(NO3)2 grams CoO = mols x molar masss
Monday, March 3, 2014 at 4:58pm

Chemistry
C3H8 + 5O2 ==> 3CO2 + 4H2O dHrxn = (n*Hfproducts)-(n*Hf reactants) Look up the delta Hf values, substitut and solvef or dHrxn.
Monday, March 3, 2014 at 4:55pm

AP Chemistry
You have mols HCl = M x L = ? It will take the same number of mols to neutralize HCl since reaction ratio is 1 mol NaOH to 1 mol HCl.
Monday, March 3, 2014 at 4:53pm

chemistry
mols AgCl = grams/molar mass Is it % Cl2 you want and not chloride? (I suspect it is chloride) but I'll stick to what you posted. g Cl2 = (1.5683g AgCl x (molar mass Cl2/2*molar mass AgCl) Then %Cl2 = (g Cl2/mass sample)*100 = ?
Monday, March 3, 2014 at 4:47pm

chemistry
See your other post. Same procedure except for step 4. After mols of what you want, then M = mols/L. You know mols and M, solve for L and convert to mL.
Monday, March 3, 2014 at 4:42pm

chemistry
Here are the steps. 1. Write and balanced the equation. 2. Convert what you have to mols. mols = M x L = ? 3. Using the coefficients in the balanced equation, convert mols of what you have to mols of what you want. 4. Now convert mols of the product to grams. g = mols x molar ...
Monday, March 3, 2014 at 4:40pm

Chemistry 2
Thanks man that makes so much clearer. i posted another question similar to this but its a first order reaction. would that change how you work it or is it done the same?
Monday, March 3, 2014 at 4:40pm

Chemistry
Many portable gas heaters and grills use propane, C3H8(g). Using enthalpies of formation, calculate the quantity of heat produced when 17.0g of propane is completely combusted in air under standard conditions. Assume that liquid water is forming.
Monday, March 3, 2014 at 4:38pm

chemistry
See your other post.
Monday, March 3, 2014 at 4:37pm

chemistry
Kay, Kammy, Smith, Jen et al. Just who are you? It would be much better if you used one screen name; besides, using multiple names get less attention than more attention. CO3^2-(aq) + Mg^2+(aq) ==> MgCO3(s)
Monday, March 3, 2014 at 4:36pm

AP Chemistry
In neutralization reactions, acid + base -> salt + water HCL can be neutralized with NaOH. How many moles of NaOH will it take to neutralize 0.56 L of 0.51 M HCl?
Monday, March 3, 2014 at 4:34pm

chemistry
A student determines the cobalt(II) content of a solution by first precipitating it as cobalt(II) hydroxide, and then decomposing the hydroxide to cobalt(II) oxide by heating. How many grams of cobalt(II) oxide should the student obtain if her solution contains 46.0 mL of 0....
Monday, March 3, 2014 at 4:30pm

chemistry
A 0.5917 g sample of a pure soluble chloride compound is dissolved in water, and all of the chloride ion is precipitated as AgCl by the addition of an excess of silver nitrate. The mass of the resulting AgCl is found to be 1.5683 g. What is the mass percentage of chlorine in ...
Monday, March 3, 2014 at 4:29pm

chemistry
How many mL of 0.716 M HNO3 are needed to dissolve 7.67 g of MgCO3? 2HNO3(aq) + MgCO3(s) Mg(NO3)2(aq) + H2O(l) + CO2(g)
Monday, March 3, 2014 at 4:29pm

chemistry
How many grams of PbBr2 will precipitate when excess FeBr2 solution is added to 47.0 mL of 0.563 M Pb(NO3)2 solution? Pb(NO3)2(aq) + FeBr2(aq) PbBr2(s) + Fe(NO3)2(aq)
Monday, March 3, 2014 at 4:28pm

chemistry
When aqueous solutions of potassium hypochlorite and nitric acid are mixed, an aqueous solution of potassium nitrate and hypochlorous acid results. Write the net ionic equation for the reaction. Use H+ for the hydronium ion.
Monday, March 3, 2014 at 4:27pm

chemistry
When aqueous solutions of potassium carbonate and magnesium nitrate are combined, solid magnesium carbonate and a solution of potassium nitrate are formed. The net ionic equation for this reaction is:
Monday, March 3, 2014 at 4:27pm

chemistry
i have so many boxes to fill in for example one box +one box+one box. So how will this answer be and let me know if it is aq, l, solid in each box. thanks
Monday, March 3, 2014 at 4:26pm

AP Chemistry
50.0 mL of an HCl solution with a pH of 3.5 neutralizes 200.0 mL of a Ca(OH)2 solution. What is the molarity of the Ca(OH)2 solu- tion?
Monday, March 3, 2014 at 4:10pm

Chemistry 2
20 at t = 0 5 at t = 40 A = C e^kt 5 = 20 e^40 k .25 = e^40 k ln .25 = 40 k -1.39 = 40 k k = - .03466 so A = 20 e^-.03466 t when A = 10, we have not only the blank filled but the half life .5 = e^-.03466 t ln .5 = -.6931 = -.03466t t = 20 I think you can do it now
Monday, March 3, 2014 at 4:10pm

chemistry
Pb(NO3)2 (aq) + MgCl2 (aq) ----> PbCl2 (s) + Mg(NO3)2 (aq) Pb++ + 2NO3- + Mg++ + 2Cl- ---> PbCl2 + Mg++ + 2 NO3- Mg and NO3 the same both sides, ions so net: Pb++ + 2 Cl- ---> PbCl2 solid
Monday, March 3, 2014 at 4:02pm

Chemistry 2
For a second order reaction A <--> B, calculate the t1/2 (half life) and the k(constant) and also fill in the blanks. A (concentration) t(time) 20 0 sec 10 ? 5 40 sec 3 ? ? 200 sec t1/2=? k=?
Monday, March 3, 2014 at 3:58pm

Chemistry 2
what do you mean?
Monday, March 3, 2014 at 3:53pm

Chemistry 2
Thanks man both answers you have answered for me have checked out to mine that i have got.
Monday, March 3, 2014 at 3:42pm

chemistry
The following molecular equation represents the reaction that occurs when aqueous solutions of lead(II) nitrate and magnesium chloride are combined. Pb(NO3)2 (aq) + MgCl2 (aq) PbCl2 (s) + Mg(NO3)2 (aq) Write the balanced net ionic equation for the reaction.
Monday, March 3, 2014 at 3:30pm

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