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Chemistry

Consider the following reaction:
2Na + Cl2  2NaCl ΔH = -821.8 kJ
(a) Is the reaction exothermic or endothermic? (b) Calculate the amount of heat transferred when
5.6 g of Na reacts at constant pressure. (c) How many grams of NaCl are produced during an
enthalpy change of 16.5 kJ? (d) How many kilojoules of heat are absorbed when 44.1 g of NaCl
is decomposed into Na and Cl2 at constant pressure?

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  1. a.
    dH is -. By definition that is exothermic.

    b.
    You get 821.8 kJ for 2*23 or 46 g Na. So 5.6 g Na will give you
    821..8 kJ x 5.6/46 = ? kJ.

    c.
    Rearrange part b. You have 821.8 kJ when 2*58.5 g NaCl are formed.
    So 2*58.5 g NaCl x 16.5 kJ/821.8 kJ = ?

    d.
    See b and c parts.

    Post your work if you get stuck.

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