Question 967164


Notice that all concentrations in this problem are Volume-to-Volume concentrations.


60 ml  of  70%-solution contains  {{{70/100}}}.{{{60}}} = {{{0.7*60}}} = {{{42}}} ml  of pure acid.


After adding of  10 ml  of the pure acid the total solution volume will be  70 ml,  and the total volume of the pure acid will be  42 ml + 10 ml = 52 ml.


Hence,  the concentration of the obtained solution will be  {{{52/70}}} = {{{0.743}}} = 74.3% (approximately). 


<B>Answer</B>. &nbsp;The concentration of the obtained solution will be &nbsp;74.3% (approximately).