saintxiao

thanks for help but i still have problem with second question. i use 174ml kno3 of 2.50 M kno3 find out 0.435 mol No3 and use 218 ml mg(No3)2 of 0.750 M mg(No3)2 find out 0.3256 mol No3 what should i do next?

1.A 78.6-mL sample of HCl(aq) is diluted to a volume of 500.0 mL. If the concentration of the diluted solution is found to be 0.393 M HCl, what was the concentration of the original solution? 0.0786 L x 0.393 M = 0.500 L X ?M solution is 0.0618 M HCL is that right? 2.Assuming the volumes are additive, what is the [NO3-] in a solution obtained by mixing 174 mL of 2.50 M KNO3, 218 mL of 0.750 M Mg(NO3)2, and 145 mL of H2O? anyone show me how to do this question?