Chemistry

Two hydrides A and B of an element X contain 17.76% and 12.58% by mass of hydrogen. Identify A and B and comment on their structures.

  1. 馃憤 0
  2. 馃憥 0
  3. 馃憗 49
asked by Alice
  1. Hydrogen has the lowest atomic mass. That would make the % of hydrogen in most hydrides very low since the H atoms would be linked to much heavier atoms. The two percents given are actually high indicating that the hydrides are linked to a relatively small atom, possibly from the 2nd row of the Periodic Table: LiH, BeH2, B2H6, CH4, NH3, H2O, HF. The % of hydrogen in one of these hydrides is very close to 17.76%. Find out which one. Example:
    For BeH2,
    Be/BeH2 = (1.008)(2)/11.03 = 0.1828 = 18.28% H.
    The element we want is not Be. Try another one of the other hydrides.
    Once you know which element forms a hydride with 17.76% H, look up its atomic mass. Lets call it x for now.
    For the first compound:
    100-17.76 = 82.24% X
    Divide 82.24% by x to get m
    Divide 17.76 by 1.008 = 17.62
    Divide m and 17.62 by the smaller of the two. One ration is 1 and the other a small whole number. Those are your subscripts.
    For the 2nd compound:
    100-12.58= 87.42% X
    Divide 87.42% by x to get n
    Divide both, n and 12.58 by the smaller of the two. You should get 1 and another small whole number which are your subscripts for the 2nd compound.
    This is a challenging percent composition problem. The challenge is for you.

    1. 馃憤 0
    2. 馃憥 0
    posted by GK
  2. Correction:
    "Be/BeH2 = (1.008)(2)/11.03 = 0.1828 = 18.28% H."
    should read:
    2H/BeH2 = (1.008)(2)/11.03 = 0.1828 = 18.28% H.

    1. 馃憤 0
    2. 馃憥 0
    posted by GK
  3. I have worked out that the element is nitrogen and the first hydride is NH3. I calculated the second hydride to have the empirical formula NH2. Would the molecular formula be N2H6? I'm not too sure about the structures.

    1. 馃憤 0
    2. 馃憥 0
    posted by Alice

Respond to this Question

First Name

Your Response

Similar Questions

  1. Calculating Averages?

    A certain element has four isotopes. 5.85% of has a mass of 53.93961 . 91.8% of has a mass of 55.934939 . 2.12% of has a mass of 56.93539 . 0.282% of has a mass of 57.93328 . What is the average atomic mass of element ? Express

    asked by Alison on August 29, 2011
  2. Periodic Table

    1. The atomic mass of an element is A. the sum of the protons and neutrons in one atom of the element.** B. twice the number of protons in one atom of the element. C. a ration based on the mass of a carbon-12 atom D. a weighted

    asked by Peru on October 16, 2017
  3. Chemistry

    Element X has three istotopes, X鈦光伒, X鈦光伓, and X鈦光伕. Element X has an atomic mass of 96.344u. If X-98 has a mass of 98.0001u and an abundance of 19.8%, what are the abundances of X-96 (mass of 95.9988u) and X-95 (mass of

    asked by Laurie on October 8, 2011
  4. Chemistry

    Element X has three istotopes, X鈦光伒, X鈦光伓, and X鈦光伕. Element X has an atomic mass of 96.344u. If X-98 has a mass of 98.0001u and an abundance of 19.8%, what are the abundances of X-96 (mass of 95.9988u) and X-95 (mass of

    asked by Laurie on October 8, 2011
  5. Chemistry

    Element X has three istotopes, X鈦光伒, X鈦光伓, and X鈦光伕. Element X has an atomic mass of 96.344u. If X-98 has a mass of 98.0001u and an abundance of 19.8%, what are the abundances of X-96 (mass of 95.9988u) and X-95 (mass of

    asked by Laurie on October 8, 2011
  6. physical chemistry

    1 mole of element x has mass, 0.444 times the mass of 1mole of element Y. one average atom of element x has mass 2.96 times the mass of one atom of ^12c. what is the atomic wt. of Y?

    asked by veer on June 18, 2014
  7. chemistry

    1.what is meant by atomic number of an element? 2.the mass number of an element is 18,it contains 7 electrons.what is the number of protons and neutrons in it?what is the atomic number of the element? 3.an element has an atomic

    asked by pooja on May 4, 2012
  8. CHEMISTRY

    WHEN A 50.0g SAMPLE OF AN ELEMENT COMBINES COMPLETELY WITH ANOTHER ELEMENT TO MAKE 78.4g OF A COMPOUND. WHAT MASS OF THE SECOND ELEMENT REACTED? HOW TO i SOLVE THIS PROBLEM?

    asked by pat on September 27, 2007
  9. abdul kabir

    the half life of an element is 5 days. if we have 10gram of the element initially. what is the mass of the element after 5days and 10days

    asked by oyedotun on March 1, 2016
  10. CHEMISTRY

    A 40.0g SAMPLE OF AN ELEMENT COMBINES COMPLETELY WITH ANOTHER ELEMENT TO MAKE 112.2 OF A COMPOUND. WHAT MASS OF THE SECOND ELEMENT REACTED? hOW TO i GO ABOUT SOLVING THIS PROBLEM?

    asked by pat on September 27, 2007

More Similar Questions