Concentration of solution

1.
M1 = 0.5 M, V1 = ? cm3
M2 = 0.15 M, V2 = 250 cm^3

M1V1 = M2V2
0.5 x V1 = 0.15 x 250
Volume of 0.5 M H2SO4, V1 = 75 cm^3


2.
Avogadro's constant = L mol^-1

In (1):
No. of moles of NaNO3 = 1.0 x(36/1000) = 0.036 mol
Each mole of NaNO3 contains 2 moles of ions (1 mole of Na^+ and 1 mole of NO3^-).
No. of moles of ions = 0.036 x2 = 0.072 mol
No. of ions = 0.072L

In (2):
No. of moles of NaOH = 1.5 x(30/1000) = 0.045 mol
Each mole of NaOH contains 2 moles of ions (1 mole of Na^+ and 1 mole of OH^-).
No. of moles of ions = 0.046 x2 = 0.09 mol
No. of ions = 0.09L

In (3):
No. of moles of K2SO4 = 1 x(24/1000) = 0.024 mol
Each mole of K2SO4 contains 3 moles of ions (2 mole of K^+ and 1 mole of SO4^2-).
No. of moles ions = 0.024 x3 = 0.072 mol
No. of ions = 0.072L

Hence, (1) and (3) contain the same amount of ions.

2010-01-28 23:55:51 補充：
Reference: 老爺子