# Posts by DrBob222

Total # Posts: 54,516

chemistry

Chemistry a level
1. Write and balance the equation. 2MnO4^- + 5C2O4^2- + ? ==> 2Mn^2+ + 10CO2 +? I didn't finish the entire equation (that is I omitted the H^+, electrons, and H2O) BUT I balanced the redox part and that's all you need. 2. mols Na2C2O4 = grams/molar mass = ? 3. Using...

chemistry
Zn is above H in the activity series and silver is below H in the same series.

Chem
pOH = 0.650 -0.650 = log(OH^-) (OH^-) = 4.47 M Ca(OH)2 = 1/2 that or 2.23 M

CHEMISTRY
q = heat absorbed = mass Cu x specific heat Cu x (Tfinal-Tinitial). The sign will be +.

chem
First determine theoretical yield (TY). The actual yield (AY) is given as 1.24g. mols CaCO3 = grams/molar mass = ? Look at the equation. You get 1 mol CaO for every 1 mol CaCO3; therefore, mols CaCO3 from above will give you that many mols CaO. Convert mols CaO to grams. g = ...

chemistry
With all gases in the equation one may use a shortcut in which volumes are considered as mols. Convert 10 L O2 to ? L CO2. 10 L O2 x (3 mols CO2/5 mols O2) = 10 x 3/5 = ? L CO2.

chemistry
1.50 M x (75.0 mL/278 mL) x [139 mL/(139+139)] = ?

Science-chemistry
You need the molar mass of the compound if that is the molar enthalpy of formation of the compound. 100,000 g/molar mass = ? mols compound. What reaction is that -63 kJ/mol for?

Chemistry
heat lost by one + heat gained by other = 0. [mass Au x specific heat Au x (Tfinal-Tinitial)] + [mass granite x specific heat granite x (Tfinal-Tinitial)] = 0 Substitute and solve for only unknown, i.e., Tfinal.

lab chimistry
What compound? What's the experiment?

chemistry 11
If I divide 35.88 by 100 to get 0.3588 and divide that by 1.35 I get 0.266 for salt. sand = 65.11 (which I would round to 65.12 from the numbers); then 0.6512/3.17 = 0.205 Confirm those values and look at your calculations again. As for a negative %error, that just means the ...

chemistry 11

Chemistry
1. What is the concentration of TEOS? 2.What is TEOS?

college chemistry
mols NO = grams/molar mas = ? Using the coefficients in the balanced equation, convert mols nO to mols O2. That ratio is 4 mols NO/5 mols O2. Then remember that one mole of a gas at STP occupies 22.4 L.

Chemistry
mass Fe used = 0.32239. Convert that to mols. mols Fe = g/atomic mass = ? Using the coefficients in the balanced equation, convert mols Fe to mols Cu product. That's ?mols Fe x (3 mols Cu/2 mols Fe) - ?mols Fe x 3/2 = ? Then convert mols Cu formed to grams. g Cu = mols Cu ...

chem
The titration is HCl + NaOH ==> NaCl + H2O mols NaOH used = M x L = approx 0.01 but you need to confirm that.Since the ratio in the titration is 1 mol NaOH to 1 mol HCl, that means mols HCl in that 25 mL aliquot is the same as mols NaOH used to titrate it. Since this was a ...

Chemistry
The advantage is that most of the Mg and Ca ions are removed which means less detergent needed to clean. It also means less "bathtub" ring when the Ca and Mg ions react with soap. The con is that the Ca and Mg ions are replaced with Na ions and most health agencies ...

chemistry
equivalents = grams/eq weight = 4/40 = ? N = eq/L = ?

chemistry
Frankly, I haven't called these the H, or B or C groups. I have used alkali metal group, alkaline earth group, halogen group, noble element group, etc. There is much confusion about how the columns are numbered in the periodic table but if you understand the different ...

Chemistry
Two. There is 1 mol NH4^+ and another 1 mol Cl^-.

chem
I showed you how to do part a last night. You should have posted the entire problem then.

Chemistry
1 and 3 don't react so just the aq ions of those materials present. No ppts, no gases, etc. 2 forms CoPO4(s) PO4^3- + Co^3+ ==> CoPO4

Chemistry
CO3^2- + 2H^+ ==> CO2 + H2O

Chemistry
Cl^- + Ag^+ ==> AgCl mols Ag^+ = M x L = ? Because of the 1:1 ratio mols Cl^- = mols Ag^+. Then g Cl^- = mols Cl- x atomic mass Cl-

Chemistry
H2CO3 + 2NaOH ==> Na2CO3 + 2H2O OR H2CO3 + NaOH ==> NaHCO3 + H2O This problem is not workable with the information given. The titration of H2CO3 has TWO endpoints as shown in the two equations above. If phenolphthalein is used as the indicator the second equation is in ...

Chemistry
Not Zn^2+. It's Zn and for the reason you cite. Zn ==> Zn^2+ + 2e has the highest oxidation potential

Chemistry
Thank you Bob Pursley.

@Damon--Chemistry
I don't think there is enough information to answer this question. I believe the answer posted is for a 500 GRAM solution but it won't be 500 mL. The density of a 37% H2SO4 solution is right at 1.05 g/mL so the volume will be about 476 mL. Have I missed the boat? I ...

Chemistry
Is this0.15 m or 0.15 M Is there a part b?

chemistry
mols = grams/molar mass. You have mols and grams, solve for molar mass. I get 88. The COOH group of an alkanoic acid weighs has a molar mass of 45 which leaves88-45 = 43. A methyl group (CH3) is 15 while the methylene group (CH2) is 14 so I would make an educated guess that ...

Basic science chemestry
Do you have a question? What you have posted is confusing. By the way you need to learn how to spell chemistry.

Chemistry
I can draw the three for 1. For 2 I can draw two; i.e., 1-hydroxy propane and 2-hydroxy propane although those may not be proper IUPAC names. For 3 I can draw any structure for C2H4Cl and certainly not three. I can draw for at least one structure for C2H5Cl, at least one for ...

Chemistry
Let's call CH3COOH just HAc. It is dissociates 50%, that means it starts at 0.2M and ends up at 0.1M with the products 0.1M .........HAc --> H^+ + Ac^- I........0.2.....0......0 C....-0.5*0.2...0.1.....0.1 E.......0.1.....0.1.....0.1 Plug this into the Ka expression but...

chemistry
If you have pure Cu and you add oxygen to it, the Cu forms CuO and the Cu gains weight (mass) because of the added oxygen.

Chemistry
It does dissolve directly in water.

Chemistry
Basically, gases are compressible while liquids and solids are not. Doubling the temperature doubles the volume of a gas; certainly the volume of a solid and volume of a liquid are not doubled. Solids, liquids, and gases simply don't have the same properties.

Chemistry
CuO + H2 ==> Cu + H2O

Chemistry

Chemistry
Carbon dioxide, CO2, is not a chemical reaction by itself. However, it is a product of a chemical reaction. When fossil fuels burn or gasoline is used in cars, CO2 is one of the products formed. Usually water, H2O, is formed at the same time CO2 is formed.

Chemistry (chromatogrphy)aphy)
I assume from the last part of your post that you are using paper chromatography. If so,the paper is the stationary phase and the solvent is the mobile phase. Compounds that are very soluble in the mobile phase (in this case I think you used different solvent), they will move ...

Math/Chemistry
50.0 x 1E-5 = ? grams. Multiply by 1000 to convert to mg. Compare with 5.5E-3.

Chemistry
Why not just change the final weight of the crucible, make new calculations, and see what effect it is.

chemistry
Water is less dense at lower temperatures.

Chemistry
How many mols do you want? That's mols = M x L = ? Then = mols = grams/molar mass. You know mols and molar rmass, solve for grams.

Chemistry
See below

Chemistry
Note that 0.16m means 0.16 MOLAL while 0.16 M means 0.16 MOLAR. I am sure you meant 0.16 M. Na2CO3 + 2HCl == 2NaCl + H2O + CO2 mols HCl = M x L = approx 0.002 but you need a more accurate answer than that. Using the coefficients, convert mols HCl to mols Na2CO3. That's 1/2...

Chemistry

Chemistry
1. mols CaI2 = grams/molar mass = ? 2. mass - volume x density = 12.0 mL x 1.000 g/mL = ? 3.m = mols/kg solvent 4. I'm confused about the term "molality of all solutes). I assume you want the m of Ca ion and m of I ion. m Ca^+ is the same as m CaI2. m I^- is 2x m CaI2.

Chemistry
This is a limiting reagent (LR) problem and you know that when amounts are given for BOTH reactants. Hg(ClO4)2 + Na2S ==> HgS + 2NaClO4 1a. mols Hg(ClO4)2 = grams/molar mass = ? b. mols Na2S = g/molar mass = ? 2a. Using the coefficients in the balanced equation, convert ...

Chemistry
In equal quantities like this I would write it as NaAc + HCl ==> HAc + NaCl So you essentially have a solution of HAc (now not 1M but 0.5M) and you calculate the pH of that solution. Do the same for solution II using the HH equation, then find the ratio of the pH o the two ...

Chemistry 2
#1. You need to find the caps key and use it. 2. You need to proof you post. "What is the boiling point of ethylene---I assume you meane ethylene glycol". mols ethylene glycol = grams/molar mass = ? kg solve is 0.074 kg delta T = Kb*m with Kb approx 0.5 but that an ...

Chemistry
pH 2 is(H^+) = 10^-2 M pH 12 is(H^) = 10^-12 M Assume a volume of 100 mL (0.1 L) of each, then mols pH 2 soln = M x L = 0.01 x 0.1 = 0.001 mols. mols pH 12 soln = 0.000000000001 x 0.1 = very small. Add the two volumes and you have 200 mL (0.2L) of essentially 0.001 mols so (H...

Chemistry
methanoic acid = HM millimols HM = 100 x 0.05 = 5. ...HM + OH^- ==> M^- + H2O I...5....0.......0..... add......x........... C..-x...-x.......x E..5-x...x.......x Substitute the E line into the Henderson-Hasselbalch equation and solve for x = millimols NaOH. Then M NaOH = ...

chemistry
Al^3+ + 3e ==> Al 2 O^2- ==> O2 + 4e

chemistry
Let's take a 20 g sample which means 10 g CaO and 10 g impurity. Convert 10 g CaO to ? g CaCO3. That's 10 x (molar mass CaCO3/ molar mass CaO)= about 18 g CaCO3 but you need a more accurate answer. Total mass sample now is 18 + 10 = approx 28 and % CaCO3 = (18/28)*100...

Chemistry
mL1 x M1 = mL2 x M2 25.0 x 7.50 = 500 mL x M2

Chemistry
I'm sorry but I don't have any equations or formulas to measure morality. If you want molarity, however, it is: mols NaHCO3 = grams/molar maqss Then M = molarity = mols/L solution

Chemistry
If you Google that long name you find an explanation that it has 1 chiral carbon which leads to 1 enantiometer. Find the 1 chiral C atom. If you can't find more than that, then 1 enantiometer is it.

Chemistry

chemistry
Not a. phen stands for 1,10 phenothroline. en stands for ethylenediammine tetraacetic acid. To answer this, draw a square for a and b and see if there are cis and trans isomers. For the others draw an octahedron and check for cis and trans isomers.

chemistry
You need to find the arrow key. 4Fe + 3O2 ==> 2Fe2O3 a. mols Fe = grams/atomic mass = ? Using the coefficients in the balanced equation, convert mols Fe to mols O2. b. mols Fe = grams/atomic mass = ? Using the coefficients in the balanced equation convert mols Fe to mols ...

Chemistry

Chemistry
Yes, T of calorimeter increases. q = heat transferred = heat capacity calorimter x (Tfinal-Tinitial)

Chemistry
For 1 the ionic equation is ok but you need a 2 for AgC2HO2 and a 2 for AgCl to balanced the molecular equation. 3Fe+2(aq) + 3SO-4(aq) + 6Na+(aq) + 2PO3-4(aq) ---> Fe3(PO4)2(s) + 6Na+(aq) + 3SO-4(aq) 3SO-4 should be 3[000SO4]^2- 2PO3-4 should be 2[PO4]^3- The CuCl2 equation...

Chemistry
dHrxn = (n*dHf products( - (n*dHf reactants) Substitute and solve

Chemistry
http://www.chemteam.info/SigFigs/SigFigRules.html https://www.chem.tamu.edu/class/fyp/mathrev/mr-da.html

Chemistry
62.9296(0.692) + x(1-0.692) = 63.546 Solve for x.

Chemistry
Assuming the 50 mL solution + 100 mL H2O equals 150 mL (that is that the solutions are additive, and technically, they are not additive), then that 100 on the right should be 150 and Mb = 0.3125/3 = ? Also note that you are allowed three significant figures so I would report 0...

Chemistry
Look at the order of filling. That is 1s, 2s, 2p, 3s, 3p, 4s, 3d etc. So if n = 3 and l = 2, the electrons must be a 3d electron. For n = 4 and l = 0, that's a 4s electron. The 4s is lower energy than the 3d. I think B.

chemistry
Draw an octahedran and plug the liqands onto the sides got c,d, and e (those have coordination of 6. Fopr a and b do a square and plug in the ligands. If you can do one of them in two different ways; i.e., so that two of the ligands are cis in one position and trans in another...

chemistry
Mg + I2 ==> MgI2 mols Mg = grams/molar mass Using the coefficients in the balanced equation, convert mols Mg to mols I2. that's a 1:1 reaction. Now convert mols Mg to grams. g = mols MgI2 x molar mass MgI2.

Chemistry
The rules I remember for reactions: 1. A rxn will occur if a (a meaning one) ppt forms. It goes without saying that if two ppts form there will be a reaction also. Your rxn is an example. 2. A rxn will occur if a gas is formed. Example: 2Na + H2O ==> 2NaOH + H2 3. A rxn ...

Chemistry
When Ca reacts with water the product is Ca(OH)2 and that is less soluble than, for example, NaOH when Na reacts with water. Both will give a bright pink color with phenolphthalein.

Chemistry
magnesium(solid) hydrochloric acid (solution) magnesium chloride (solution) hydrogen (gas)

Chemistry
When placed in water they form strong alkalies (bases).

Chemistry
3NaOH(aq) + FeBr3(aq)→ Fe(OH)3 + 3NaBr

Chemistry
Mg and Ca have only two electrons in the outside shell. K and Na have only one All are easily removed (Mg and Ca less so than K and Na) so they are quite reactive.

Chemistry
I don't understand the question.

Chemistry
I worked one like this yesterday. Only the numbers have changed. The process is the same. Try it. I'll help you through if you explain in detail what you don't understand.

chemistry
73.67 g is right but I would round that to 74. I don't know that there is a way to "DERVIVE" the formula. That's one of those things you learned in the 4th grade arithmetic class. But here is a common sense approach. If I gave you a basket containing 5 lbs of...

chemistry
That's 2 Al for 6e or 1 Al for 3e so that factor should be 2*26.98/6e or 26.98/3e. That doubles the answer. Some books use 96,485 instead of 96,500. Thanks for showing your work. That always makes it easier to find the error.

Chemistry
All of the answers for 1 are true but I don't think A is the best one. 2,3,4 are not right.

Chemistry
And what is the final temperature of the water?

Chemistry
An exothermic reaction has dH - so it must be B or E

Chemistry
I would look at D

AP Chemistry
I don't know how you're defining the term potential level. The potential to oxidize Cl ion to Cl2 gas is -1.36 v and that for Na ion to Na metal is -2.71 v. The potential of the cell is -1.36 + (-2.71) = -4.07 v. Therefore, you need at least +4.07 v to electrolyzs ...

Chemistry
http://wwwchem.uwimona.edu.jm/courses/selrules.html

Chemisrty
I have corrected the typo in the equation below. H3C6H5O7(aq) + 3NaHCO3(q)---Na3C6H5O7(aq) + 3H2O(l) + 3CO2(g) 1. mols NaHCO3 = grams/molar mass = 1/84 = 0.0119 Convert mols NaHCO3 to mols H3C6H5O7 using the coefficients in the balanced equation. That's 0.0119 x (1 mol ...

Chemistry
I don't know the meaning of 5A----10^20. "in a cobalt 'what' contain 5A---10^20 'what'"?

Chemistry
Materials, usually chemical molecules, in which one end of the molecule is positive and the other end is negative.

Chemistry
With regard to atomic weight or atomic mass see this. https://www.google.com/search?q=what+unit+is+atomic+mass&ie=utf-8&oe=utf-8 But one mole of the element will weigh that number shown in grams. with regard to the ionic radius of He and H, I don't have an answer. I didn&#...

Chemistry
You're ok. I substituted the numbers into equation 2 (with pKa = 5.3 and pH = 5.6

Chemistry
I tried that early on. The problem I had is that we have two equations and three unknowns. The unknowns are a, x, and pKa. I don't know how you solve for a in terms of x without involving pKa. So I'm inclined to think your solution is not correct but I don't know ...

Chemistry
I checked and you did respond to my question; however, you didn't answer it.

Chemistry
CH3COOH = HAc. .....HAc --> H^+ + Ac^- I....0.5.....0......0 C.....-x.....x......x E....0.5-x...x......x Ka = (H^+)(Ac^-)/(HAc) Substitute the E line into Ka expression and solve for H^+ initially in the 10 L. Then (OH^-) = Kw/(H^+) to calculate OH^- Double that. ...

Chemistry
All three of these reactions are double replacement. Therefore, all you need to do is to write the reaction and look up each compound to see what state it is. For example, NH4Cl(aq) + AgNO3(aq) → NH4NO3(aq) + AgCl(s) etc.

Chemistry