We know that molarity is equal to the moles of solute/liters of solution. In the problem, they tell us that there is 1 liter of solution, so we have to find how many moles of solute there are. Since they give us the amount of solute in grams, we can use the molar mass of CO₂ to find how many moles there are:
Carbon has a molar mass of 12.012 g/mol
Oxygen has a molar mass of 15.999 g/mol. Since there are 2 (which we can see from the subscript), we have to multiply this number by 2. (15.999)(2)=31.998 g/mol
We can find the total molar mass of CO₂ by adding these two numbers up:
12.012+31.998=44.01 g/mol
We can then use dimensional analysis to find how many moles there are:
100 g CO₂ (1 mol CO₂/44.01 g CO₂)
=2.27 moles of CO₂
Now that we have the moles of solute and liters of solution, we can plug them into our molarity equation:
M= 2.27 moles/ 1 liter
M= 2.27 moles/liter