Answer:
If a reaction produces a gas such as oxygen or carbon dioxide, there are two ways to measure the reaction rate: using a gas syringe to measure the gas produced, or calculating the reduction in the mass of the reaction solution.
It is fact that
6.023
×
10
23
formula units of barium nitrate have a mass of
16.6*10^23
⋅
g
. This is what we specify when we say molar mass. And thus the mass of
5.30
×
10
22
formula units of barium nitrate is the quotient multiplied by the molar mass:
5.30
×
10
22
6.023
×
10
23
m
o
l
×
16.6*10^23
⋅
g
⋅
m
o
l
−
1
A3B2
bond is ionic
A is in group 2 (you can pick any like Ca)
B is in group 5 (like B)
the other question:
the reason is they are neutral gas and they already have 8 electrons except for He which is 2 and are completely stable so don't want to loose any electron vs Li and Na which have only 1 electron in the outer layer and are willing to loose that one to become stable.
Al (+3)
NO3 (-1)
So basically you need 3 NO3 and one Al to produce Al (NO3)3