Answer : The formula of unknown compound is
and the name of the compound is potassium carbonate.
Explanation :
First we have to calculate the moles of


Now we have to calculate the moles of unknown alkali metal carbonate.
Let the alkali metal be, 'M'.
The balanced chemical reaction will be:

From the balanced reaction we conclude that,
As, 1 moles of
react with 1 mole of

So, 0.0109 moles of
react with 0.0109 mole of

Now we have to calculate the molar mass of unknown alkali metal carbonate.


Thus, the molar mass of
is 137.6 g/mole
Now we have to calculate the mass of alkali metal.


Thus, we conclude that the alkali metal will be potassium (K) that has 38.8 grams of mass.
So, the formula of unknown compound is
and the name of the compound is potassium carbonate.