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pui
Lv 4
pui 發問於 科學及數學化學 · 5 年前

五題化學短答題不懂?

1. What is the coefficient of M when the following equation is completed and balanced if M is an alkali metal?

M (s) +H2O (l)->

2.Oxides of most nonmetals combine with water to from ______.

3. Among the hydrogen halides, only ____is a weak acid.

4. The only noble gas that does not have the ns2np6 valence electron configuration is ______.

5. The first ionization energies of the elements _____ as you go from left to right across a period of the periodic table, and _____ as you go from the bottom to the top of a group in the table.

1 個解答

評分
  • 5 年前
    最愛解答

    1.

    If M is an alkali metal, it reacts with water to give M+ ion. MOH & H2 is formed.

    Write down the reactants & products first:

    a M + b H2O ------> c MOH + d H2

    where a, b, c, d are integers.

    a = c due to conservation of no. of atoms of M

    b = c due to conservation of no. of atoms of O

    2b = c + 2d due to conservation of atoms of H

    2M + 2H2O ------> 2MOH + H2

    2.

    acid. e.g.

    Carbon dioxide to give Carbonic acid

    Sulfur dioxide & Sulfur trioxide to give Sulfurous acid & Sulfuric acid, respectively

    Nitrogen dioxide to give Nitrous acid & Nitric acid

    Phosphorous pentoxide to give Phosphoric acid

    3.

    Hydrogen fluoride (HF)

    due to the strong bond between hydrogen & fluorine

    4.

    helium. Obvious.

    5.

    increase; decreases

    look at the change in effective nuclear charge

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