Posted by lily on Thursday, October 4, 2007 at 6:53pm.
First, magnesium hydroxide is Mg(OH)2
Second, if #1 give off heat then delta H = -1203.6 what. Joules. kJ. And is that kJ/mol or kJ for the reaction as written.
Third, since you show heat given off for all three equations, did you omit the - sign for #2 reaction; i.e., should that be -37.1 and what are the units.
the units are all kj/mol. and no i did not, the second equation is supposed to be endothermic.
ok. got it. If #2 is endothermic, then you should have written it as
Mg(OH)2(s) + heat ==> MgO(s) + H2O(l)
and I am going with Mg(OH)2 and not MgOH2
Use equation #1 as is but if delta H is kJ/mol, then you must multiply by 2 to obtain delta H for the reaction.
Reverse #2 and double it. Also write the reaction as doubled.
Use equation 3 in the same direction but double it if kJ/mol for there are 2 mols. Check my thinking. I wrote this out on paper and I have
2 Mg(s) + 2O2(g) + 2H2(g) ==> 2Mg(OH)2(s)
delta H for the final is the sum of the delta Hs for each as rewritten. Check my thinking. You must make certain that the delta Hs you have written are kJ/mol for that makes a big difference whether #1 and #3 are doubled or not.
Related Questions
chemistry - Calculate the standared enthalpy of formation of solid Mg(OH)2 given...
Chemistry - I can not determine the answer for this problem...can someone please...
chemistry - 1) MgO (s) + 2H (aq) -> Mg+2 (aq) + H2O (l) 2) Mg+2 (aq) + H2...
chemistry - 1 2Mg + o2 --> 2Mgo 2 MgCo3 --> MgO + Co2 3 Co2 + Ca(...
Chemistry - Did I do these right? Can someone let me know if I did them ...
chemistry - How many grams of MgO are produced when 40.0grams of 02 react with ...
Chemistry - Given the following data, calculate the enthalpy change for the ...
chemistry - For the question(s) that follow, consider the following equation. ...
chemistry - please assist me with this themochemistry question Given the ...
chemistry 101 - given the reaction: 2mg + o2-----> 2mgo . when 4.32g of ...
For Further Reading
