Question

Which of the following equations is balanced correctly and has the correct products for the reactants RbNO3 and BeF2?

3RbNO3 + 3BeF2 → Be(NO3)3 + 3RbF, because Be increases in charge from 2+ to 3+ when it is replaced
2RbNO3 + BeF2 → Be(NO3)2 + 2RbF, because Be keeps a 2+ charge throughout the reaction
RbNO3 + BeF2 → BeNO3 + RbF2, because Be keeps a 1+ charge throughout the reaction
2RbNO3 + BeF2 → Be(NO3)2 + 2RbF, because Be increases in charge from 1+ to 2+ when it is replaced

Answer 1

2RbNO3 + BeF2 → Be(NO3)2 + 2RbF, because Be keeps a 2+ charge throughout the reaction

Answer 2

2RbNO₃ + BeF₂ → Be(NO₃)₂ + 2RbF, because Be keeps a 2+ charge throughout the reaction

Step-by-step explanation:

2RbNO₃ + BeF₂ → Be(NO₃)₂ + 2RbF, because Be keeps a 2+ charge throughout the reaction

Rb is a +1 cation, NO3 is a -1 anion, Be is a +2 cation and F is a -1 anion.

In writing an ionic compound the charge of the cation becomes the subscript of the anion and the charge of the anion becomes the subscript of the cation.

So the ionic compound formed between Be2+ and F- is BeF2. The ionic compound formed between Be2+ and NO3- is Be(NO₃)₂.

As there are two NO₃ on the product side it is balanced by writing a 2 coefficient before RbNO₃ on the reactant side.

And as there are two F on the reactant side it is balanced by writing a 2 coefficient before RbF on the product side.