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The law of fixed composition

Portrait of John Dalton

Quiz: Dalton's Atomic Theory

1. Which of the following is not a postulate of Dalton's atomic theory?
atoms combine in simple whole number ratios to form compounds
atoms of a single element can have different masses
atoms are not created or destroyed in chemical change
chemical change is a rearrangement of atoms
different elements have atoms of different masses
2. 1.008 grams of hydrogen combines with 35.453 g of chlorine to form 36.463 g of a pure compound (hydrogen chloride). Dalton's explanation for this experimental fact might be:
hydrogen and chlorine atoms always combine in a 1:35 ratio.
hydrogen and chlorine atoms aren't created or destroyed in the process so the reactant mass is the same as the product mass.
this is a simple mixture of elements because the ratio isn't a whole number ratio
chlorine accepts hydrogen's electron to form polar covalent hydrogen chloride
one atom of hydrogen combines with 35.453 atoms of chlorine in this reaction
3. Hydrogen combines with oxygen in a 1:8 weight ratio to form water. If every molecule of water contains two atoms of hydrogen and one atom of oxygen, an atom of oxygen must weigh:
16 times the mass of a hydrogen atom 1/8 times the mass of a hydrogen atom
8 times the mass of a hydrogen atom1/16 times the mass of a hydrogen atom
4. Dalton suggested that atoms were indestructible and unchangeble to explain:
why elements combine in fixed weight ratios to form compounds
why compounds combine in fixed weight ratios in chemical reactions
why mass is conserved in chemical reactions
why elements are characterized by the mass of their atoms
5. When elements react, their atoms combine in:
1:1 ratios
arbitrary proportions
a simple whole number ratio (unique for each pair of elements)
simple whole number ratios (more than one possible)

Dalton's Atomic Theory
Page 1: Introduction
Page 2: Dalton's assumptions Five steps forward and one step back.
Page 3: Atoms in compounds An "invisible hand" fixes atom ratios in compounds
Page 4: Atoms in reactions Dance of the atoms
Page 5: Learning check Take a quiz on Dalton's Atomic Theory
Page 6: References and resources

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General Chemistry Online! Quiz

Copyright © 1997-2005 by Fred Senese
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Last Revised 07/25/05.URL: http://antoine.frostburg.edu/chem/senese/101/atoms/dalton-quiz.shtml