answer for 2 and 3
2
you got 1,6 liter of a 0,05 mol/ liter solution ---> 0,05 * 1,6 = 0,08 mol
you add 0,4 liter which makes 2 liter 0,08 mol in 2 liter = 0,04 mol/l
that makes 0,04 mol of H+
the pH is the negative decadic log of the conz of H+ pH = -log[H+] = -log [0,04] = 1,4
pH can never be negative!!!!
3
you got 3l*0,2mol/l = 0,6 mol K2CrO4
and 6l*0,4mol/l = 2,4 mol BaCl2
you got 9l of solution, you generate 0,6 mol BaCrO4
1,8 mol Ba2+ stay in solution
1,8mol/9l = 0,2 mol/l
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