1. I

    How to convert from mol% to wt%?

    so the concentration of molecule A is 0.5% mol. The rest of the molecules are water. This is calculated by (number of molecules of A / total number of molecules) x 100 More specifically, this is [20 / (20 + 3980)] x 100 We are given that the molecular weight of A is 136 g/mol. I have no idea...
  2. H

    Need help with Chem Lab!

    Hello everyone! Hopefully all of my fellow Americans have been enjoying a nice Thanksgiving break, and well.. everyone else... I hope you have been having a great week! Anyway, I need some major help with my Chemistry lab. Essentially we did the lab in school, and we had to answer questions...
  3. W

    Mole and Molar Mass

    Is the number of atoms in 0.5 mol of oxygen gas and 0.5 mol of iron the same? My answer is NO because: Oxygen gas exists as molecules (2 oxygen atoms in one oxygen molecule) Therefore, in 0.5 mol of oxygen gas, there were 0.5 x 2 x 6 x 10^23 = 6 x 10^23 oxygen atoms. But, 0.5 mol of iron has...
  4. M

    Calculating Mole Masses, Combustion

    Hello I am stuck with these 5 homework problem that I am unable to solve or set it up, can anyone help me how to get the answer to these? 1) Calculate the number of grams and pounds of CO2 that result from the combustion of 1 gallon of gasoline (we will assume that gasoline is mostly octane...
  5. L

    Some chemistry questions I need help with

    1. a)You put [H2] = 0,70M, [I2] = 0,70M and [HI] =1,50M. And the K value is 49. Decide the equilibrium concentrations. H2 + I2 <-> 2HI b) Which concentration HI gets inserted if the iodine concentration at a new equilibrium is 0,42Molar. The K value is still 49. c) What happens with the...
  6. S

    Mole Fraction

    Hello, I have been stuck on this question for quiet a while. I have calculated the ideal amount of moles of the gases using Pv=nRT and got 0.222 mol. I also calculated the number of moles of CO2 produced at 0.341 moles. But I have no idea what to do next!! If some one can guide me I would...
  7. S

    Mole Fraction

    Hi I am having trouble solving for the number of moles of (CH3)2CO! If some one can get me going on solving this question, I would appreciate it!
  8. J

    Mole fraction

    Dear, Is there any one out there who is very adept in computing mole fraction of metallic salt mix with silicate minerals? Thanks, James
  9. H

    Stoichiometric Virtual Lab Help?

    Hey, I'm new here! Anyway, I'm doing a virtual chemistry lab on stoichiometric. I have completed the actual experiment; what I'm stuck on are the questions. Here is one of the questions: Below is the balanced equation for the reaction. Review the results of your...
  10. E

    Mole calculations confusion (please help!)

    Hello guys! Im really confused with this one part of calculating the number of moles in 1.00 gram the last part in bold is confusing me. why is the 2 negative? can someone please explain finding a number of moles in a certain number of grams? im really confused : ( this is what the teacher...
  11. F

    More Grav. Analysis & Mole Calculations

    Q1: Kyotorphin (mole mass = 337.4 g/mol) is a small molecule, which has a role in pain regulation. A sample of cerebrospinal fluid taken from a patient has a kyrotorphin concentration of 280 ng/L. Find the number of kyrotorphin molecules in one millilitre of cerebrospinal fluid. n = CV = (2.8 x...
  12. F

    Gravimetric Analysis and Mole Calculations

    Q1: The amount of nickel in a sample of steel was determined by the following method. 3.18 g of the steel was dissolved in a mixture of hydrochloric and nitric acids. This converted all of the nickel into Ni{2+} ions. The solution was neutralised with dilute ammonia and a solution of...
  13. M

    Help with the mole and mass

    Hi guys! I have a few questions - I just cant get my head round it and wondered if I could get some help? 1) Ethanol burns according to the following reaction C2H5OH (l) + 3 O2 (g) → 2 CO2 (g) + 3 H2O (g) 1mol 3mol 2mol 3mol How many grams of reactants are required to produce 15 gr of water...
  14. F

    Mole calculation

    A chloride of an element X has a chemical formula of XCl4. A 1.97g sample of this compound was added to water. A precipitate XO2 and hydrochloric acid were formed. When the precipitate was removed, the filtrate was made up to 300cm3 in a volumetric flask. A 30cm3 portion of this solution was...
  15. T

    mole concept 15 t

    a 30 gram sample of calcium carbonate is completely converted into anhydrous calcium chloride. what will be the mass of the anhydrous product. a)30g b) 33.3g c) 15g d) 66.6g e)213g MR (caco2)= 84.1g/mol MR (cacl2)= 111.1g/mol no. of mole of caco2= 0.356mol mass of cacl2= 111.1 x 0.356 = 39.5 ????
  16. T

    mole concept 11t

    8g of X2O3, an oxide of element X, contains 5.6g of X. How many moles of X does 5.6g of the element contain? a) 2.4/16 x 2/3 b) 2.4/16 x3/2 c) 8/16 x 2/3 d) 8/16 x 3/2 X->5.6g 0> 2.4g mr (O2)= 32g/mol no. of moles O2= 0.075 after this, what to do?
  17. T

    MOle concept 21

    When 0.5g of magnesium is treated with an excess of hydrochloric acid, what volume of gas at room temperature and pressure will be produced? a) 5cm3 b) 480cm3 c) 240cm3 d) 120cm3 e)500cm3 why? mr(MG)= 24.3 equation: Mg(s) + 2HCl(aq) --> MgCl2(aq) + H2(g) no. of moles of Mg= 0.5/24.3=0.02...
  18. T

    Mole concept 22

    If 6 moles of sulphur dioxide are oxidised to sulphur trioxide, how many moles of oxygen molecules are required a) 2.0 b) 1.0 c) 1.5 d) 3.0 e) 6.0 why? To find the number of moles, i used 6 divided by the MR of the sulphur dioxide, which is 64.1, which gets me 0.09. What do i do after...
  19. K

    Question about stochiometry

    Please help :( Use the equation to calculate the following: 2KMnO4(aq) + 16HCl(aq) → 2MnCl2(aq) + 5Cl2(g) + 8H2O(l) + 2KCl(aq) (a) the moles of H2O that can be obtained from 24.2 mL of 0.694 M HCl (b) the volume of 0.844 M KMnO4 needed to produce 1.38 mol MnCl2 (c) the volume of 2.86 M HCl...
  20. M

    Heat absorbed per mole and other math problems

    Hello, We're working on bond energies in my chemistry course, and I'm having some trouble with bond energies. I used the Table of Bond Energies, but didn't end up even close to the answer for this and other math-related questions: I'm not too sure how to know which is which. Thanks!