Adding concentrations to obtain mass I have a question that gives two concentrations and asks for the mass of HCl formed by the reaction.

I have two concentrations:

250mL of 4.00M $\ce{H2SO4}$, and

250mL of 1.00M $\ce{NaCl}$.

Here is the balanced reaction equation:

$\ce{H2SO4 + 2NaCl -&gt;Na2SO4 + 2HCL}$

I know how to find the mass once I find the moles, molecular weights and then grams by multiplying the two.

However, how do I add those two concentrations? I assume the mixture will be at least 500mL, but how do I add the molarity? 

Thanks!
Your working equation is correct.
$$\ce{H2SO4 + 2NaCl -&gt;Na2SO4 + 2HCl}$$


Find the amount of substance of protons of each solution via $n=c\cdot V$.



   $n(\ce{H+})=2~\mathrm{mol}$, $n(\ce{Cl-})=0.25~\mathrm{mol}$



What is the limiting agent?



   Chlorine



How many moles of hydrogen chloride can only be formed?



   $n(\ce{HCl})=0.25~\mathrm{mol}$



Calculate the mass of hydrogen chloride via $m = n\cdot M$



   $M(\ce{HCl})=36.5~\mathrm{g/mol}$, $m(\ce{HCl})=9.1~\mathrm{g}$