1. B

    Finding the molar mass from an Osmotic Pressure

    An unknown, non-ionizing compound with a mass of 0.108 g is dissolved in water to make 100.0 mL of solution. If the solution has an osmotic pressure of 0.169 atm at 20.8 ºC, what is the molar mass of the substance? -------- The answer is 154.1g/mol. I got this question wrong and can't figure...
  2. Z

    Molar concentration

    How many litres of (NH3) (the volume is measured in standart conditions) must be dissolved in 200 g of a 10% solution NH4OH to obtain 15% solution of the ammonium hydroxide?
  3. U

    Molar calculations - making CuCl2

    I am making CuCl2 - Cu (s) + 2 HCl (aq) -> CuCl2 + H2 My calculation is this: Molar weight of copper is ~63 g/mol thus I have 10/63= ~ 0.16 mol of copper. Making CuCl2 from it should take 2*0.16 ~ 0.32 mol of acid. 32% solution HCl ~ 10 mol which means 1mol ~ 100ml so I need 0.32*100ml ~...
  4. 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...
  5. S

    Finding molar mass of copper

    Hi, in my experiment I determined that copper has a specific heat capacity of 0.275 J/(g* Celsius). How do I approximate it's molar mass using this piece of information?
  6. R

    Basic Molar Ratio Equation Help Needed

    Need help/explanation... given 1L of 0.5M of both NaClO and NaS2O3, what is the equation for reaction between 5mL NaClO (Sodium Hypochlorite) and 45mL Na2S2O3 (sodium thiosulfate) with depreciating mL values of 5;45, 10;40, 20;30, 30;20, 40;10, 45;5 with each other without the presence of...
  7. A

    Molar fraction

    I have a following porblem i do not understand clearly: The molar fraction of antimony in copper melt Xsb Xsb=n_sb/n_melt=Csb/Cmelt [1] (the antimony weight is much smaller than melt weight) n_sb: mole number of antimony n_melt: mole number of melt Csb: concentration of antimony in melt Cmelt...
  8. B

    A Molecule With a Similar Molar Mass as CCl4?

    I need to find a molecule that has a similar mass as CCl4 but it can't be another non-polar molecule. PCl3 was the closest I could get it but had a lower melting and boiling point. I need to prove that a polar molecule with a similar molar mass will have a higher melting and boiling point...
  9. T

    Simple Change in Molar Volume Question

    Hi, The question states: "Calculate the change in molar volume for the reaction of corundum (Al_2O_3) in liquid water to from gibbsite (Al(OH)_3). My question would be, is when I look at the table that was provided, (Al(OH)_3) is listed in aquas form but does not list a molar volume. But if I...
  10. E

    Physical Chemistry Help - Molar Heat Capacity

    A aluminium bar has a mass of 60 grams and a molar heat capacity , Cm,p of 24.3 JK-1mol-1 is heated to a temperature of 75 degrees Celsius, and dropped into a bath of water at 15 degrees Celsius. The final temperature of the aluminium bar and bath of water is 20 degrees Celsius. Given that the...
  11. K

    Molar enthalpy?

    I've learnt previously that Molar enthalpy is in terms of kJ per mole of the limiting reagent, but my school's chemistry notes said that it is in fact kJ per mole of the limiting reagent times the coefficient of the limiting reagent in the stoichiometric equation. so instead of just Q/n, it is...
  12. J

    How to calculate molar mass

    Assuming that atmospheric air is a mixture of nitrogen and oxygen in the mole ratio 79:21 estimate the molar mass of air.
  13. J

    Molar Ratios

    I have the answer to A, but need help setting up B. I believe I need to use the molar mass of 447.894 and subtract 2.2395 - 1.6990 PART 1. A modern chemist, attempting to reproduce a medieval recipe for azurite, combined copper metal, calcium hydroxide (Ca(OH2)), and acetic acid (CH3CO2H) in a...
  14. K

    Sig Figs and Molar Mass

    So, I get molar mass but how do you know how many sig figs need to go after finding molar mass?
  15. M

    Finding Moles,Molar ratio,Water loss

    Given a sample hydrate of .854g and an anhydrous salt (NiSo4) of .503g: (a) Calculate the mass of the water driven off (b) The Percent of water in the hydrate (c) The number of moles of water in the hydrate sample (d) The number of moles of the anhydrous salt (e) The molar ratio of anhydrous...
  16. B

    molar mass

    What is the molar mass of chloroform if 4.85 grams is .918 liters at 35 degrees celcius and 850 torr? Not sure what equation to use, maybe pv=nrt but is n=molar mass or does that give me moles. help
  17. R

    Help with calculating Molar Mass!

    Hiya, Doing some practice questions for a test I have coming up and this question came up. Different to any I've done before? Magnesium metal reacts with dilute hydrochloric acid to form hydrogen gas: Mg(s) + 2H(+)(aq) -> Mg(2+)(aq) + H2(g) Haemoglobin is the protein that transports the O2...
  18. E

    Molar concentration of Ca(OH)2

    How to calculate the molar concentration of calcium hydroxide? Given that pH = 10 and a = 1, where a = degree of dissociation. I don't know, how exactly translate formula, but teacher suggested to use this one: Concentration (ion) = concentration (substance) * n * a, where n = count of ions...
  19. P

    Molar Enthalpy

    So, I signed up for an online Chemistry lab and halfway through the semester I've realized that it was a huge mistake, but now I am stuck. I have a lab that I'm working on but I can't seem to figure out what to do. I think I started it, but I'm really dumbfounded as to what to do and how to...
  20. D

    molar solution

    the question is can you make a 1M solution at 0 C for Ca(OH)2 , the solubility is given as 0.185g/100ml. i thought no. the mass of Ca(OH)2 is 74. that means one mole of the compound must weigh 74g. (moles=grams/mol mass) so if you can only get 1.85g / liter based on solubility, to me that...