Question

how do I caculate molarity?

stock concentration: [Fe]= 0.04mg/mL

volume of stock used, mL 10mL

what is [Fe] in standard, M?

when volume of stock used is 5mL , 2mL and 1 mL, what is [Fe]?

Answer 1

[Fe] = 0.04 mg/ mL

[Fe] = 0.04 / 56 = mol/mL = 0.00071 mol/mL

in 10 mL of stock solution no of moles of Fe = 0.00071 * 10 = 0.0071 mol

molarity of the solution = 0.0071 / 0.010 = 0.714 M

(b) V = 5 mL

in 5 mL of stock solution no of moles of Fe = 0.00071 * 5 = 0.00355 mol

molarity of the solution = 0.00355 / 0.005 = 0.71 M

(c) V = 2 mL

in 5 mL of stock solution no of moles of Fe = 0.00071 * 2 = 0.00142 mol

molarity of the solution = 0.00142 / 0.002 = 0.71 M

(d) V = 1 mL

in 5 mL of stock solution no of moles of Fe = 0.00071 * 1 = 0.00071 mol

molarity of the solution = 0.00071/ 0.001= 0.71 M