Wednesday, November 6, 2013

6 Random Questions Answered

Every so often, AUS-e-TUTE randomly selects 6 questions that have been asked in the last few hours by people who are not AUS-e-TUTE members.
Today's selection is:

1/ Question from Canada, "ammonia gas undergoes a combustion to produce nitrogen dioxide gas and water vapour. write and balance the equation"

Answer: 2NH3 +7/2O2 → 2NO2 + 3H2O

2/ Question from USA, "How do you convert weight percent to mass fraction?"

Answer:  percent by mass (weight) = mass (weight) fraction x 100

3/ Question from USA, "what are the physical properties of metals due to metallic bonding?"
Answer:  The physical properties of solid metals are:
  • conduct heat
  • conduct electricity
  • generally high melting and boiling points
  • strong
  • malleable (can be hammered or pressed out of shape without breaking)
  • ductile (able to be drawn into a wire)
  • metallic lustre
  • opaque (reflect light)

4/ Question from USA, "Can air be separated by physical means?"
Answer: Yes. Air is a mixture so it can be separated by physical means.

5/ Question from USA, "How do you calculate atomic mass from relative abundance?"
Answer: Given the relative atomic mass (r.a.m.) of an element and the mass of each of its isotopes, the relative abundance of each isotope can be calculated:
let y/100 = abundance of isotope 1
and (100 - y)/100 = abundance of isotope 2
then, r.a.m = [y/100 x mass isotope 1] + [(100 - y)/100 x mass isotope 2]
and solve for y

6/ Question from USA, "How do you turn empirical formula into molecular formula?"
Answer: molecular formula = whole number x empirical formula

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