Which compounds are lewis acids? select all that apply

a. nahco3
b. br−
c. (ch3ch2)2hc+
d. bbr3

A, C and D

Explanation:

Lewis acid  are compounds that accept a pair of non-bonding electron while Lewis base  are compound that donate non-bonding electron pairs. Lewis acid in the options are NaHCO₃ because it has both acidic and basic properties ( ampholyte),  (CH3CH2)2HC+ is deficient of electron and  BBr3 because boron has an incomplete octet configuration and deficient of two electron

n2(g) + 3h2-> 2nh3(g)   this is the balanced equation

note the mole ratio between n2, h2 and nh3.   it is 1 : 3 : 2   this will be important.

moles n2 present = 28.0 g n2 x 1 mole n2/28 g = 1 mole n2 present

moles h2 present = 25.0 g h2 x 1 mole h2/2 g = 12.5 moles h2 present

based on mole ratio, n2 is limiting in this situation because there is more than enough h2 but not enough n2.

moles nh3 that can be produced = 1 mole n2 x 2 moles nh3/mole n2 = 2 moles nh3 can be produced

grams of nh3 that can be produced = 2 moles nh3 x 17 g/mole = 34 grams of nh3 can be produced

note:   the key to this problem is recognizing that n2 is limiting, and therefore limits how much nh3 can be produced.