a) c = n/v. v = 0.5 L, you need to find moles from the m=50.0g use n = m/MM
should get n = 0.202... moles
c = 0.40048...
c = 0.400 mol/L (3sf)
b) Dilution questions always use c1v1=c2v2
c1 = 0.400 mol/L, v1 = unknown
find c2 first, c = n/v, where v = 1 L
use n = m/MM to find moles using the m=1.0g
should get n = 0.0040048... moles
c2 = n/v
c2 = 0.0040048.../1
c2 = 0.00400 mol/L (3sf)
v2 = 1L
sub all into c1v1 = c2v2
(0.400)v1 = (0.00400)(1)
v1 = 0.01 L or 10 mL