why is it that when an unknown carbonate of group one or two (inc H) reacting w/ HCl, the mole ratio is 1:1

Could you be talking about half neutralizing Na2CO3? If completely neutralized, it is a ratio of 1:2.

Na2CO3 + 2HCl ==> 2NaCl + H2O + CO2
CaCO3 + 2HCl ==> CaCl2 + H2O + CO2.

If half neutralized, then
Na2CO3 + HCl ==> NaHCO3 + NaCl.

Not just Na

I mean all group 1 and 2 elements

Li2CO3

Na2CO3
K2CO3
Rb2CO3
Cs2CO3
All the same.
Group I is group I. They all go through the same reaction, at least with HCl.

When an unknown carbonate of Group 1 or 2 (including hydrogen) reacts with hydrochloric acid (HCl), the mole ratio is 1:1. This means that for every mole of the unknown carbonate, one mole of HCl is required for a complete reaction.

To understand why the mole ratio is 1:1, we need to look at the balanced chemical equation for the reaction. Let's take the example of an unknown carbonate represented by the formula MCO3, where M represents a Group 1 or 2 metal:

MCO3 + 2HCl -> MCl2 + H2O + CO2

In this equation, one mole of MCO3 reacts with 2 moles of HCl to produce one mole of MCl2 (a metal chloride), one mole of water (H2O), and one mole of carbon dioxide (CO2).

From the balanced equation, we can see that the mole ratio between MCO3 and HCl is 1:2. However, if we consider the limiting reagent concept, we can determine the ideal stoichiometry of reactants.

In this case, the unknown carbonate is limited, which means that after completely reacting with 2 moles of HCl, there will be no excess HCl left. This implies that the moles of the unknown carbonate will be completely consumed by the HCl, resulting in a 1:1 mole ratio between the unknown carbonate and HCl.

Therefore, to ensure a complete reaction and avoid excess reagent, it is recommended to use a 1:1 mole ratio between the unknown carbonate and HCl when reacting them together.