Calculate the mass of potassium in the sample : g Submit Answer Tries 0/3 Calculate the percent of potassium in the sample : % Submit Answer Tries 0/3 Calculate the volume of standard NaOH that reacted with iron : mL Submit Answer Tries 0/3 Calculate the mass of iron in the sample : g

Answer is explained below.

Explanation:

Calculate the mass of potassium in the sample :

1st equivalence point corresponds to K+ ;

mol K+ = moles of NaOH used in titration (from V1 ) = 0.100 mol/L * 6.00 ml/1000 ml/L = 0.00060 moles

mass of K+ in sample =  0.00060 moles* 39.1 g/mol = 0.02346 g

Calculate the percent of potassium in the sample :

mass of K+ in sample / mass of sample *100

0.02436 g / 0.195 g *100 = 12.03 %

Calculate the volume of standard NaOH that reacted with iron :

V2 -V1 = 16.40 ml - 6.00 ml = 10.40 mL

Calculate the mass of iron in the sample :

three moles of hydroxide ion are required to react with each mole of iron ion in the salt.

moles of Fe = 1/3* moles of NaOH used in titration (form V2 - V1) = 0.100 mol/L * 10.4 ml/1000 ml/L /3 = 0.000347 moles

mass of Fe in sample = (moles of Fe)(55.85 grams/mole) = 0.000347 moles*55.85 g/mol = 0.01936 g

Calculate the percent of iron in the sample :

mass of Fe in sample / mass of sample *100

0.01936 g / 0.195 g *100 = 9.93 %