Question

(Please show work) Assume you dissolve 10.35 g MgCrO4 in enough water to make 250.0 mL of solution. The molarity of the solution is

A)0.543M

B)0.128M

C)0.762M

D)0.254 M

E) none of these

Answer 1

Molar mass of MgCrO4 = 1*MM(Mg) + 1*MM(Cr) + 4*MM(O)

= 1*24.31 + 1*52.0 + 4*16.0

= 140.31 g/mol

mass of MgCrO4 = 10.35 g

we have below equation to be used:

number of mol of MgCrO4,

n = mass of MgCrO4/molar mass of MgCrO4

=(10.35 g)/(140.31 g/mol)

= 7.377*10^-2 mol

volume , V = 250.0 mL

= 0.25 L

we have below equation to be used:

Molarity,

M = number of mol / volume in L

= 7.377*10^-2/0.25

= 0.295 M

Answer: E