What mass of solute is needed to prepare each of the following solutions? a. 3.00 L of 0.125 M K2SO4 b. 550 mL of 0.015 M NaF c. 700 mL of 0.350 M C6H12O6

A.

M = 0.125 M

V = 3.0 L

M=n/V (L) ⇒ n = 0.125 mol/L * 3.0L = 0.375 mol

MM of K2SO4

K2 = 2 * 39 = 78 g/mol

S = 32 g/mol

O4 = 4*16 = 64 g/mol

MM = 78g/mol + 32g/mol + 64g/mol = 174 g/mol

mass = n*MM = 0.375 mol*174 g/mol = 65.25 g

b.

M = 0.015 M

V = 0.55L

n = 0.015 mol/L * 0.55L = 0.00825 mol

MM NaF

Na: 23g/mol

F: 19 g/mol

MM = 23g/mol + 19g/mol = 42g/mol

mass = n * MM = 0.00825 mol * 42g/mol = 0.3465 g

c.

n = M*V (L) = 0.350 mol/L * 0,700L = 0.245 mol

MM = 6*12 g/mol + 12*1g/mol + 6*16g/mol = 180 g/mol

mass = n*MM = 0.245 mol * 180g/mol = 44.1 g