4. Use the kinetic theory to explain the following (a) When you take a block of butter out of the fridge, it is quiet hard. After 15 minutes it is soft
enough to spread

Air particles hits the butter particles from collisions that air transfer kinetic energy to the butter. The butter particles then begins to move from each other more faster. So when the particles are becoming lose, the butter (solid) turns to soft butter (slight liquid, slight solid).

"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"