Chapter 16, Problem 16.26P

(a)

Interpretation Introduction

Interpretation:

How many moles of triiodide $\left({\text{I}}_3^{-}\right)$ ions are formed by this reaction has to be calculated.

Concept introduction:

Mole defined as amount of chemical substance contains number of particles as the number of atoms in 12g of C-12.

(b)

Interpretation Introduction

Interpretation:

Concentration of Sodium thiosulphate $\left({\text{Na}}_{\text{2}}{\text{S}}_{\text{2}}{\text{O}}_{\text{3}}\right)$ has to be calculated.

Concept introduction:

Molarity is one of the concentration unit.  Molarity is defined as number of moles of the solute in one litre of solution.

$\text{Molarity =}\frac{\text{Number of moles of the solute}}{\text{1L solution}}$

(c)

Interpretation Introduction

Interpretation:

Weight percentage of Ascorbic acid in the unknown has to be calculated.

Concept introduction:

The mass percentage or weight percentage of compound can be calculated by taking the calculated mass of the substance to the total mass of the sample whole multiplied by 100.

The mass percent can be calculated with formula,

$Masspercent(inpercentage)=\frac{Calculatedmass(ingrams)}{totalmass(ingrams)}\times 100$

(d)

Interpretation Introduction

Interpretation:

It is the matter whether starch indicator is needed at the starting or near the end point in the titration of part (c) has to be explained.