Given the data in the table below, δh°rxn for the reaction ag2o (s) + h2s (g) → ag2s (s) + h2o (l) is kj. substance δh∘f(kj/mol) ag2o (s) -31.0 ag2s (s) -32.6 h2s (g) -20.6 h2o (l) -286

quartz

explanation:

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"