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Posts by DrBob222

Total # Posts: 54,973

Chemistry
no reaction. Rxn occur for only a few reasons. 1. A ppt is formed. none here. 2. A gas is formed. none here. 3. A weak electrolyte is formed. none here. 4. redox rxn. none here.

Chemistry
Something tells me you haven't posted all of the problem. You can't get NaOH with an NH3 solution.

chemistry
You made a typo. You meant HNO3 and you omitted H2O as one of the products. Cu + HNO3-Cu(NO3)2 + NO + H2O Cu on left has oxidation number 0; on right is +2. N on left is +5 and on right is +2 (in NO) and for the moment ignore the NO3 ion in Cu(NO3)2. So multiply the Cu change ...

Chemistry
Adam, I can't begin to decipher your post. No caps, no arrow, no differentiation between reactants and products, no question.

Chemisty
Use the coefficients. 18 L CO2 x (7 mols O2/4 mols CO2) = 18 x 7/4 = ? The answer is NOT 22.909.

Analytical chemistry
mols B6 = grams B6/molar mass B6 =? Then M B6 = mols B6/L soln = mols B6/0.1L = ? Do same for caffeine. Note: I assume you want concn in molarity; however, not that you could do it in g/L, M, m, N, etc.

Chemistry
M HI = mols/L = 4.00/2.00 = 2.00 .......2HI ==> H2 + I2 I ......2.......0....0 C.......-2x.....x....x E.....2-2x......x....x Substitute the E line into Keq expression. You know x = (H2) = 0.4,calculate concns and Keq from that.

chemistry
Technically you can't do this without knowing the reaction. But USUALLY, when the reaction isn't know, one assume that one takes the molarity and multiplies by the total positive or negative charge. mols Na2CO3 = grams/molar mass. M = mols/L N = M x 2.

chemistry
hydrated

Chemistry
Six problems in here. What do you know about any of these?

chemistry
Actually, this can't be answered because you didn't identify the numbers; however, I have assumed the first number is n, the second is l and the third and fourth are ms. If that isn't correct ignore the following. i no. Can't have two ms of 1/2 ii no, Can't...

AP Chem
This is a limiting reagent (LR) problem and you know that because amounts are given for BOTH reactants. CaCl2 + 2AgNO3 ==> Ca(NO3)2 + 2AgCl mols CaCl2 = M x L = ? = approx 0.001 but you need to confirm. mol AgNO3 = M x L = approx 0.001 x 1 = 0.001. You see the mols AgCl are...

Chemistry
I would use specific heat water as 1 cal/g*C and not do the Joule to calories conversion. q = cal = mass H2O x specific heat H2O x (Tfinal-Tinitial). If you want to use 4.182 J/g*C, the do that and convert to cal by 1 cal = 4.182 J.

Chemistry
15 mg/mL x # mL = 12 mg Solve for # mL.

chemistry
mass = volume x density You have the mass and density, substitute and solve for volume.

Chemistry
I think you just made a a couple of typos. You left no space between Sn+2Ag and you omitted the 2Ag on the right. Sn + 2Ag ==> An^2+ + 2Ag

chemistry
If you intended KClO2 (and not KClO3), here is he scoop. K is +1. It's ALWAYS +1 because it's in group I of the periodic table. Cl is +3 on the left (remember all compounds are 0 so K + Cl + 2O = 0; therefore, 1 + ? + 2*-2 = 0. That makes Cl +3) and O is -2 for EACH ...

Chemistry
I think it's important that you define what you mean by 80:20 mixture. Is that 80:20 by mass, by moles, or by volume?

chemistry
a. What are you talking about. What subject, what experiment, what source? b. What sources have ALREADY been mentioned?

Chemistry 20
The 1.82 is 100%. That is theoretical yield (TY). The 1.94 is actual yield (AY) % yield = (AY/TY)*100 = ? You can take the difference.

Chemistry 20
Technically, none since H2CO3 decomposes as fast as it is formed. H2CO3 ==> H2O + CO2. However, ignoring that, then 2HNO3 + Na2CO3 ==> 2NaNO3 + H2CO3 The equation tells you that 2 mols HNO3 will produce 1 mol H2CO3. So 1.2E-3 mols will produce ......?

Chemistry 20
This is done the same way as the HNO3 problem.

chemisty
Cu + 2AgNO3 ==> Cu(NO3)2 + 2Ag mols Cu = grams/atomic mass = ? mols Ag = 2x mols Cu

Chem1020
Use PV = nRT. You know V(in L), n,R and T(in kelvin). Solve for P in atm and convert to mm. 1 atm = 760 mm Hg.

Chem1020
PV = nRT. You know P(must be in atm), V(must be in L), R and T(must be in kelvin). Solve for n = mols. Then n = grams/molar mass. You know n and grams, solve for molar mass.

Chemistry
dE = 2.18E-18(1/x^2 - 1/10^2)

Chemistry
50 g x (atomic mass Cu/molar mass CuO) = ? g Cu.

Chemistry
You need Keq and the reaction for that K.

chemistry
dT = 15 x (6/2) = /

Qualitative analysis
copper carbonate

Qualitative analysis
All form a hydroxide insoluble in water. Pb^2+ is the only one to form Pb(OH)2 which dissolves in an excess of NaOH by forming a complex ion of [Pb(OH)4]^2-

oops--Qualitative analysis (Chem)
Fe)OH)2 is green and gelatinous with white streaks and changes to a red/brn.

Qualitative analysis (Chem)
Al(OH)3 is not colored. Cu(OH)2, Fe(OH)2 and Fe(OH)3 are colored. Fe(OH)2 is the only one that is colored and changes color on standing because it is being oxidized to Fe(OH)3 by air. So Fe(OH) is greenish and it changes to a red/brown.

Chemistry
React with what to form what? I assume that is to decompose to H2 and O2 but I don't know that. Write the equation. 2H2O ==> 2H2 + O2 546.234 mols H2 x (2 mol H2O/2 mol H2) = 546.234 x (2/2) = 546.234 x 1/1 = 546.234 mol H2O. It's done with the coefficients. 2H2O

Chemistry
CH4 1 mol CH4/4 mol H or 4 mol H/1 mol CH4

Chemistry
I don't know what the C stands for but you seem to have ignored it in the calculation. I didn't go through the calculations with a calculator but the methods seems OK EXCEPT that you haven't added in the heat from steam at 100 to steam at 110

chemistry
melting ice at zero is mass ice*heat fusion = ? Cooling 540 g water from 25 to zero is mass H2O * specific heat ice x (Tfinal-Tinitial). Put those together to obtain (mass ice*heat fusion) + (mass H2O x specific heat water x (Tfinal-Tinitial) = 0 Solve for mass ice.

Chemistry
I said you were right yesterday.

chemistry
What are the conditions? T, P? I will assume STP but technically this problem can't be worked without that informatiion. 1.7 dm-3 H2 produced. Convert to mols. That's 1.7 x (1 mol/22.4 dm-3) = ? Convert to mols Zn. mols Zn = mols H2 (look at the coefficients in the ...

chemistry
g C = 1.500 g CO2 x (atomic mass C/molar mass CO2) = ? g H = 0.401 g H2O x (2*atomic mass H/molar mass H2O) = ? g O = 1.00-g C - g H = ? Convert grams to mols. mols C = g C/12 = ? mols H = g H/1 = ? mols O = g O/16 = ? Find the ratio of the elements to each other with the ...

Chemistry
What's Ksp for CaCO3? What's (H3O^+)?

Chemistry
thio (sulfur) compounds pyridines (N compounds)

Chemistry
mass = volume x density. You know mass and density, substitute and solve for grams.

@CaSO4...chemistry
You are removing products. Le Chatelier's Principle says that if a system in equilibrium is disturbed, then the system will shift so as to undo what we did to it. Therefore, it we remove the products, more CaSO4 will decompose to form the products we removed. You can take ...

chemistry
Please don't post another question as an answer to another question. A. See below for ethanol problem. B. Convert 2 kg glucose to L ethanol formed using the same procedure used in the previous problem. This will give you the theoretical yield (TY)( that's the yield as...

chemistry
C6H12O6(aq) ? 2 C2H5OH(l) + 2 CO2(g) mols glucose = grams/molar mass = ? mols ethanol = 2x that (look at the coefficients in the balanced equation). g ethanol = mols ethanol x molar mass ethanol. Convert to mL. volume in mL = grams/density.

Organic chemistry (QA)
This is hardly organic chemistry. Some reasons for pptn rxns. 1. A ppt is formed. 2. A gas is formed. 3. A weak electrolyte is formed. You asked only about pptn so look at the equations and see if a ppt will form. Basically this requires that you know the solubility rules for ...

Chem
First, you can NOT write an equation because you don't know the formula of gold chloride not the formula of gold nitrate.. The Cl in gold chloride was converted to AgCl. So how much Cl must have been there with the gold? That's 464 mg x (atomic mass Cl/molar mass AgCl...

Chemistry
I agree with you.Book must be wrong.

Chemistry
A. mols Al = grams/atomic mass = ? This is n in part B. B. Use PV = nRT. You know n, R, V and T. Remember V is in L, T in kelvin, R=0.08205. Solve for P in atm. C. Ptotal = pH2 + pH2O. Ptotal and pH2O are given. Solve for pH2.

chemisty
I assume you want an equation. 2Na + I2 ==> 2NaI

chemistry
1/(2E5)^3 = 1/(2E15) = 1.25E-16

Chemistry
I would assume 20 g Ne and 20 g He (but any number will do as long as it is the same for both). mols Ne = grams/atomic mass = ? mols He = grams/atomic mass = ? Total mols = ? XNe = mols Ne/total mols pNe = XNe*Ptotal = ?

Chemistry
Whatever number you choose, I guess, since you didn't post any conditions.

Chemistry
I worked this for you yesterday. http://www.jiskha.com/display.cgi?id=1479258354

Chemistry
I need more info than that.

chemistry
q = mass H2O x dHvap.

Chemistry
How can we help you with this without doing all of the work?

Chemistry
mols Al(OH)3 = grams Al(OH)3/molar mass Al(OH)3 = ? To do part b just rearrange the equation above to grams = mols x molar mass and substitute the data for Mg(OH)2. Remember to convert grams to mg at the end.

Chemistry
You're right. They are that.

Chemistry
Your abswer if 7 g makes no sense since specific heat is measured in J/g*C (or KJ)or cal/g*C. I'm not sure the problem can be worked without knowing the calorimeter constant.

Chemistry
CaCO3 ==> CaO + CO2 Use PV = nRT and solve for n for CO2 Convert mols CO2 to mols CaCO3, then to grams CaCO3 Finally, multiply g CaCO3 by 2 since it is only 50% pure.

chemistry
Just add the electrons, protons will be the same, look up the atomic number.18+2+10+4 looks like 34 = Se to me.

@A--Chemistry
Probably you should show your work. I don't buy those numbers. And yes, limiting reagent is a factor.

chemistry
https://answers.yahoo.com/question/index?qid=20081102155715AAfdYzQ

Chemistry
ka1 = (H^+)(HC2O4^-)/(H2C2O4) ka2 = (H^+)(C2O4^2-)/(HC2O4^-) You get (H3O^+) from pH. You're given C2O4^2- and H2C2O4. Plug and chug.

Chemistry
I found pKa for the base to be 7.76; therefore, = 7.76 + log (0.02/0.02) so the pH of this solutiion is 7.76 and no HCl needs to be added/

@Kitty A.----Chemistry
It seems several students think by using both boys and girls names we will think they are different people. Not so. How do we know the same person is using different screen names. Easy. The IP address, which shows when the question/response is posted, tells us the computer ...

Chemistry
Ms. Sue is right. You get faster and better help if you don't change screen names. 2CaO + 2SO2 + O2=> 2CaSO4 mols SO2 - 1E6/molar mass SO2 = ? Using the coefficients in the balanced equation, convert mols SO2 to mols CaSO4. Now convert mols CaSO4 to grams. g CaSO4 = ...

Chemistry
2K3PO4 + 3CoCl2 ==> Co3(PO4)2 + 6KCl

Chemistry
See your other posts.

Chemistry
This is just another stoichiometry problem. Find your post above and follow the same guidelines.

Chemistry
C'mon. You're wasting our time. See your other posts.

Chemistry
See your other post.

Chemistry
I balanced that Co and phosphate equation for you. What is it you don't understand about these equations? I can help do one but if you have problems we need to know how to help so you can do these yourself.

Chemistry
Didn't I do this for you a couple days ago? http://www.jiskha.com/display.cgi?id=1479076160

Chemistry
What reaction below? See here. https://www.webelements.com/lawrencium/

chemistry
N2 + 3H2 ==> 2NH3 With gases one can take a shortcut and work the problem as if volume = mols. 12 dm3 H2 x (2 dm3 NH3/3 dm3 H2) = 8 dm3 NH3 if the yield were 100%. It formed 2 dm3; therefore, %yield = (2/8)*100 = ?%.

Chemisty
1 mol salicylic acid = 1 mol aspirin; so .......

chemistry
You get 393.5 kJ for 12 g C. You want 39.3 kJ; therefore, (393.5 kJ/12 g C) x #g C = 39.3 kJ. Solve for #g C.

Chemistry
Hints: you must supply the details. A. Add dil HCl and observe bubbles CO2. Add BaCl2 after all of the CO2 has been released. B. Add BaCl2 C. Acidify the solution, heat to drive off CO2, add AgNO3. Cations: A flame test B. flame test C. Add concentrated NaOH.

Chemistry
heat gained by cold water + heat lost by hot coffee = 0 [mass cold H2O x specific heat H2O x (Tfinal-Tinitial)] + [mass coffee x specific heat coffee x (Tfinal-Tinitial) = 0 Substitute and solve for mass cold H2O, then convert to mL. mass = volume x density. You know density ...

Chemistry
Hz. c = f*w = frequency x wavelength. freq is measured in Hz and wavelength in meters. c is speed of light = 3E8 m/s

Chemistry
195 kcal/hr x #hr = 145 kcal Solve for hr and convert to minutes. #hr x (60 min/hr) = # min

Chemistry
Use PV = nRT and solve for n = mols. Then mols = grams/molar mass. You know mols and molar mass, solve for grams.

Chemistry
This is a limiting reagent (LR) problem; you know that because amounts are given for BOTH reactants. mols Cu = grams/atomic mass = ? mols HNO3 = M x L = ? Using the coefficients in the balanced equation, convert mols Cu to mols NO. Do the same and convert mols HNO to mols NO. ...

Chemistry
Two ways to do this, one short way and one long way. Long way. CaCO3 ==> CaO + CO2 mols CaCO3 = grams/molar mass = ? Using the coefficients in the balanced equation, convert mols CaCO3 to mols CaO. Then convert to g CaO. g CaO = mols CaO x molar mass CaO. Short way. 20 g ...

chemistry
heat lost by Co + heat gained by H2O = 0 [mass Co x specific heat Co x (Tfinal-Tinitial)] + [mass H2O x specific heat H2O x (Tfinal-Tinitial) = 0 Subsitute and solve for Tf which is the only unknown in the equation.

chemistry
See your other post.

chemistry
%H2O = [(5*molar mass H2O/molar mass CuSO4.5H2O)]*100 = ?

Chemistry
You are right that mols = grams/molar mass. I think your problem, often the problem with on-line values from a data base, is that you have reported an answer with too many significant figures. 222/98.0 = a max of 3 places. You have reported 4. Round that to 2.26 (or 2.27 ...

Chemistry
(H3O^+)(OH^-) = Kw = 1E-14

Chem
pH of NaF solution is determined by the hydrolysis of the F^-. .......F^- + HOH ==> HF + OH^- I.....0.1.............0....0 C......-x.............x....x E....0.1-x............x....x Kb for F^- = (Kw/Ka for HF) = (x)(x)/(0.1-x) and solve for x = (OH^-). Convert to pH. The ...

Chemistry
insufficient data.

oops typo---Chemitry
So you need 1 mole of Ca(OH)2 for every mole of HCl. Should be. So you need 1 mol Ca(OH)2 for every 2 mols HCl. The Conversion factor is ok.

@Dr Dave--oops--Chemistry
Total mass = 15x5 = 75g of BaTi(SiO3)3 should be 15 carats x (1 g/5 carats) = 3 grams and go from there.

Chemistry
H2A + 2NaOH ==> Na2A + 2H2O mols NaOH = M x L = ? mols H2A must be 1/2 that (look at the coefficients). mols H2A = grams/molar mass. You know mols and grams, solve for molar mass.

Chemistry
1250 J = mass H2O x specific heat x (Tfinal-Tinitial) Solve for Tf.

Chemistry
See your other post above. Same idea.

Chemistry
600 = mass H2O x specific heat H2O x (Tfinal-Tinitial)

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