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  1. J

    Latent Heat Problem/ Phase Change .Please Help

    Latent Heat Problem/ Phase Change.....Please Help!!!!!!! At 1:00pm you place an ice cube tray in the freezer. Each of the 12 1-gram cubes has a temperature of 20°C. At 1:10 the water temperature has dropped to 12°C. At what time will you have ice? i have been messing around with this problem...
  2. J

    Chem Problem

    i worked out .05844 mol in 1 kg for NaCL and .11098 mol in 1 kg of CaCl2 is this correct
  3. J

    Need help with chem problem

    mole fraction= amount (mol) of solute / amount (mol) of solute + amount (mol) of solven mass percent= mass of solute/ mass of solute + mass of solvent x 100 molality = amount mol of solute/ mass kg of solvent i know the equations do i just plug the quantities in or is there more to it...
  4. J

    Chem Problem

    Thanks yeah i should of picked that up i got that one......can you please help me with one of the others i have posted im strugglin on those
  5. J

    Chem Problem

    8.46 e11 g does that sound reasonable
  6. J

    Chem Problem

    I have a total of 3.02 e10 moles he takes in so would i just need to convert that to grams?
  7. J

    Chem Problem

    I understand how to convert from moles to grams, etc im just not sure how i would take the CO amount then throw in the amount he inhales and how many hours to figure it out.
  8. J

    Chem Problem

    I am really not sure.....i am pretty new to chemistry and not very good at it, can i get some help
  9. J

    Problem i need some help with

    I think I understand that but what equations will help me get closer to the solution in each case?
  10. J

    Kinematic problem help

    What does u represent in these equations and i am having trouble finding time, what steps do I need to find this?
  11. J

    Need help with chem problem

    Homework Statement A solution is made by disolving 0.40 mol isopropanol (C3H7OH) in 0.70 mol water. (a) What is the mole fraction of isopropanol? (b) What is the mass percent of isopropanol? % (c) What is the molality of isopropanol? m Homework Equations...
  12. J

    Chem Problem

    Homework Statement Air in a smoky bar contains 4.3 10-6 mol/L of CO. What mass of CO is inhaled by a bartender who respires at a rate of 13 L/min during an 9.0 h shift? in g Homework Equations The Attempt at a Solution Can someone let me know what steps to take with...
  13. J

    Chem Problem

    Homework Statement "De-icing salt" is used to melt snow and ice on streets. the highway department of a small town is decideing whether to by NaCl or CaCl2 for the job. The town can obtain NaCl for $0.36/kg. What is the maximum the town should pay for CaCl2 to be cost effective? in kg...
  14. J

    Chem problem need help

    Chem problem need help.... Homework Statement How would you prepare the following aqueous solutions? (a) 1.10 kg of 0.0515 m ethanol (C2H5OH) from ethanol and water Add___ g C2H5OH to ____ g H2O. (b) 511 g of 15.0 mass % HCl from 35.3 mass % HCl Add___ g of 35.3% HCl to ___ g of...
  15. J

    Problem i need some help with

    Homework Statement A 200kg weather rocket is loaded with 100 kg of fuel and fired straight up. It accelerates upward at 35.0 m/s^2 for 34.0 s, then runs out of fuel. Ignore any air resistance effects. What is the rocket's maximum altitude? How long is the rocket in the air...
  16. J

    Kinematic problem help

    OK im just not sure what do with the equations, and what is s representing in these equations?
  17. J

    Kinematic problem help

    Kinematic problem help!!!! Homework Statement David is driving a steady 31.0 m/s when he passes Tina, who is sitting in her car at rest. Tina begins to accelerate at a steady 2.80 m/s^2 at the instant when David passes. How far does Tina drive before passing David? What is her speed...
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