The pure vapour pressure of benzene (C6 H6) is 745 torr; the pure vapour pressure of toluene (C7H8) is 290 torr. What is the mole fraction of benzene in a benzene/toluene mixture whose total vapour pressure is 500 torr? ( Give your answer to 3 dp}

"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"

the volume increases

c. electrical charges of ionic bonds.