posted by Shirley.K.Silver
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?
dH is -. By definition that is exothermic.
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.
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 = ?
See b and c parts.
Post your work if you get stuck.