250cm^3 OF 0.2 MOLAR POTASSIUM SULPHATE SOLUTION IS MIXED WITH25OCM^3 OF 0.2 MOLAR KCL SOLUTION.THE MOLAR CONCENTRATION OF K POSITIVE IONS IS
0.2 MOLAR 0.25 MOLAR
0.3 MOLAR O.35 MOLAR

Question

250cm^3 OF 0.2 MOLAR POTASSIUM SULPHATE SOLUTION IS MIXED WITH25OCM^3 OF 0.2 MOLAR KCL SOLUTION.THE MOLAR CONCENTRATION OF K POSITIVE IONS IS
0.2 MOLAR   0.25 MOLAR
  0.3 MOLAR   O.35 MOLAR

anonymous · Answer

First we calculate the moles of Potassium Sulfate(Sulphate).
$$250cm^3=0.25L$$
To calculate moles:
$$0.25L*0.2\frac{mol}{L}=0.05mol K_2SO_4$$
Now that we have the moles of K_2SO_4 we can determine the moles of K.
$$0.05molK_2SO_4\frac{2molK}{1molK_2SO_4}=0.1molK$$

Time to start working on the second solution:
$$0.25L*0.2\frac{mol}{L}=0.05mol KCl$$
Total moles of K in our final solution:
$$0.1molK+0.05molK=0.15molK$$
Our total solution is:
$$0.25L+0.25L=0.5L$$
From this we can calculate the Molarity:
$$\frac{mol}{V}=M$$
$$\frac{0.15mol}{0.5}=M$$
$$M=0.3\frac{mol}{L}=0.3M$$