Identify from the following list of molecules and ions which behave as Lewis acids: CO2, NH3, BCl3, Fe3+. (A) CO2 and NH3 (B) NH3 and BCl3 (C) CO2 and Fe3+ (D) CO2, BCl3, and Fe3+ (E) CO2, NH3, BCl3, and Fe3+

Answer : The correct option is, (D) CO₂, BCl₃, and Fe³⁺

Explanation :

According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.

(a)

It is a Lewis-acid because it can accepts electron pairs.

(b)

It is not a Lewis-acid because it can not accepts electron pairs but it is a base because it can donates and accept hydrogen ion.

(c)

It is a Lewis-acid because it can accepts electron pairs because it has an incomplete octet and an empty 2p orbital.

(d)

It is a Lewis-acid because it can accepts electron pairs.

Hence, the ions which behave as Lewis acids are, CO₂, BCl₃, and Fe³⁺

"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"