posted by Jenn .
What volume of 1.25M HCl in liters is needed to react completely (with nothing left over) with 0.750L of 0.300M Na2CO3?
Na2CO3 + 2HCl ==> 2NaCl + H2O + CO2
mols Na2CO3 = M x L = ?
Using the coefficients in the balanced equation, convert mols Na2CO3 to mols HCl.
Then the defintion of M HCl = mols HCl/L HCl. You know M and mols, solve for L.