At 20.°c, a 1.2-gram sample of mg ribbon reacts rapidly with 10.0 milliliters of 1.0 m hcl(aq). which change in conditions would have caused
the reaction to proceed more slowly?
(1) increasing the initial temperature to 25°c
(2) decreasing the concentration of hcl(aq) to 0.1 m
(3) using 1.2 g of powdered mg
(4) using 2.4 g of mg ribbon

"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"