The compound C2E10H12 (where E is an element) has a formula mass of approximately 144 g/mol. What is the atomic mass of E?

Explanation:

C₂E₁₀H₁₂  = 144

molecular weight of given compound

= 2 x 12 + 10 x E + 12 x 1 = 144 ( atomic weight of C = 12 , H = 1 , E = E )

24 + 10 E + 12 = 144

10 E = 108

E = 10.8

Atomic mass of E = 10.8 u .

"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"

sure im new too!

explanation: