Question

2. if you want to produce 3.75 g lithium carbonate, how many grams of carbon dioxide are necessary?

Answer 1

Answer:

2.24 grams of CO2, assuming the reaction involves LiOH reacting with CO2.

Explanation:

0 grams, if you have a bottle of LiCO3 on the shelf.  

Or should we assume we are reacting CO2 with a lithium compound?

We need to start with a balanced equation.  That is why I added the perceptive, (but crass), remark of "get it from the shelf."  

Here is one reaction that could be useful involving lithium hydroxide:

     2LiOH + CO2 = Li2CO3 + H2O

This tells us that 1 mole of CO2 will produce 1 mole of Li2CO3.  Lithium carbonate has a molar mass of 73.9 grams/mole.  If we want 3.75 grams of the grimy stuff, we'll need (3.75g/73.9 g/mole) or 0.0508 moles of Li2CO3.

We'll need the same number of moles of CO2 to produce the Li2CO3, 0.0508 moles of CO2.  

The molar mass of CO2 is 44 grams/mole.  0.0508 moles of CO2 is (0.0508 moles)*(44 grams/mole) = 2.24 grams of CO2.

If the reaction is different from the one I assumed here, do the same calculations using that balanced equation.