Ask questions and get helpful responses.
Ask a New Question
  1. Questions

chemistry

this is for a lab - determining the chemical formula of a hydrate.

suppose the hydrate was heated too quickly and some of it was lost of spattered out of the container.
explain how hthis would effect
a) the calculated percent by mass of water in the compound
b) the molecular formula u determined

THX

  1. 👍
  2. 👎
  3. 👁
  4. ℹ️
  5. 🚩
denise

  1. a). It's easier to explain with an example. Suppose we start with MgSO4.xH2O and we want to determine x.
    Suppose we took a 10.000 g sample of MgSO4.xH2O and it lost 5.116 g on heating. So the water content is 5.116 g and the MgSO4 content is 10.000 - 5.116 = 4.884 g.
    Here is what we do.
    5.116/18.015 = 0.284 = moles H2O.
    4.884/120.37 = 0.0406 = moles MgSO4.
    Then 0.284/0.0406 = 7 so the formula is
    MgSO4.7H2O.
    NOW, if we heated too fast and some of the sample spattered, what happens. When you reweigh the sample too much mass has been lost, so the mass H2O is too high and when you subtract from 10.000, the mass of MgSO4 too low. So the percent H2O is too high (70% using the numbers from b part) and the MgSO4 is too low (30% using the numbers from b part).[Percent MgSO4 should be 48.84% and percent H2O should be 51.16%.]
    b) Suppose the loss in spattering is 7.0 g just to make things simple. Then mass H2O = 7 g and 10-7 = 3 g MgSO4.
    Now 7/18=0.389
    and 3/120 = 0.025, then
    0.389/0.025 = 15.6 which we might round to 16 and the formula would be MgSO4.16H2O.
    I hope this helps.

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩
    DrBob222

Respond to this Question

First Name

Your Response

Similar Questions

  1. Chemistry

    A 5 gram sample of a hydrate of BaCL2 was heated, and only 4.3g of the anhydrous salt remained. What percentage of water was in the hydrate?

  2. Chemistry

    A hydrate of copper (II) sulfate with formula CuSO4.xH2O has a molar mass of 250.0 g/mol. 2.545 g of hydrate is heated and 63.85% of the residue is found after heating. a) Determine the value of x in the formula of the compound b)

  3. chemistry

    A 2.500 gram sample of hydrate of calcium sulfate loses 0.532 grams of water when heated. Determine the mass percent of water in the hydrate and the formula of the hydrate.

  4. Chemistry

    Washing soda is a hydrate of sodium carbonate. Its formula is Na2CO3 X xH20. A 2.714 g sample of washing soda is heated until a constant mass of 1.006 of Na2CO3 is reached. What is x? What is the experimental mass percent of water

  1. Chemistry

    What is the variable x in the following hydrate formula NaCl xH2O if the mass of sodium chloride is 58g and the mass of the water is 36g

  2. Chemistry

    A 25 g sample of a hydrate of Ca(NO3)2 was heated, and only 1.7 g of the anhydrous salt remained. What hydrate of Ca(NO3)2 was tested?

  3. Chemistry

    7. A student conducts an experiment on a different hydrate. The empty crucible is heated to a constant mass of 24.330. A sample of the unidentified hydrate is placed in the crucible, and the total mass is 31.571 g. The crucible

  4. chemistry

    Epsom salts, a strong laxative used in veterinary medicine, is a hydrate, which means that a certain number of water molecules are included in the solid structure. The formula for Epsom salts can be written as MgSO4 ยท x H2O,

  1. Chemistry

    A hydrate of zinc nitrate has the formula Zn(NO3)2 . xH2O. If the mass of 1 mol of anhydrous zinc nitrate is 63.67% of the mass of 1 mol of the hydrate, what is the value of x?

  2. Chem 11

    So I did a lab determining the chemical formula of a hydrate. I really just need somebody to check this over for me. We had to find the molecular formula of a hydrate of copper (2) sulphate, CuSO4 .xH2O. My observation table looks

  3. Chemistry 11

    So I did a lab determining the chemical formula of a hydrate. We had to find the molecular formula of a hydrate of copper (2) sulphate, CuSO4 .xH2O. My observation table looks like this: Mass of clean, dry test tube: 21.6g Mass of

  4. chemistry

    A sample of a hydrate of CuSO4 with a mass of 250 grams was heated until all the water was removed. The sample was then weighed and found to have a mass of 160 grams. What is the formula for the hydrate? CuSO4 * 10 H2O CuSO4 * 7

Still need help? You can ask a new question.