posted by Morgan .
You have 10.0 ml of a 5.0% NaCl solution. To this you add 5.00ml of a 2.0% NaCl solution. What is the molarity of NaCl in this final mixture?
1L of 5% NaCl has 50ml of NaCl, so 10ml has 0.5ml of NaCl
1L of 2% NaCl has 20ml of NaCl, so 5ml has 0.1ml of NaCl
So, you end up with .6ml of NaCl in 15ml of solution, or 4%