Calculate the number of moles of each ion present in 2.00 ×10^2 cm^3 of (a) 0.200 M NaCl, (b) 0

Calculate the number of moles of each ion present in 2.00...

Calculate the number of moles of each ion present in $2.00 \times 10^{2} \mathrm{~cm}^{3}$ of (a) $0.200 \mathrm{M} \mathrm{NaCl}$,
(b) $0.350 \mathrm{M} \mathrm{K}_{3} \mathrm{PO}_{4}$, (c) $1.44 \mathrm{M} \mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}$

Key Concepts

Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is a key concept in solution chemistry that allows for calculations of how much of a substance is present in a given volume of solution.

Volume Conversion

Volume conversion is essential for using molarity, as volumes are often provided in different units such as cubic centimeters (cm³) but the definition of molarity requires liters (L). Converting between these units ensures accurate calculations when determining the number of moles of solute in a solution.

Stoichiometry of Dissociation

Many compounds, particularly ionic compounds, dissociate into ions when dissolved in water. Understanding the stoichiometry of this dissociation is crucial in determining the number of moles of each ion produced from a known number of moles of the compound. This involves applying the mole ratios from the balanced dissociation equation.

Mole Concept

The mole concept is fundamental in chemistry and provides a way to count entities such as atoms, ions, or molecules by relating them to a standard number (Avogadro's number). It is used to quantify the amounts of substances involved in chemical reactions and in solution preparation and analysis.

Transcript

00:01 First of all we know that 1 cm cube that's equal to 1 milliliter and we can write that volume of solution that's equal to 2 .00 multiplying 10 raise to power 2 centimeter cube and this can be represented as 200 centimeter cube right or i can write 200 milliliter.

00:40 Now this milliliter is to be converted into liter and i hope you know that one litter consists of thousand milliliter.

00:49 So dividing this by 1000 milliliter so we will have 0 .200 liter.

00:58 So this is the volume in litter for solution.

01:01 Now the concept involved here is molarity and we will have 0 .2 .0 litter.

01:05 Since molarity, so molarity for solution, that is the method to determine the concentration of solution and that is equals to the number of moles of solute dissolved in one litter of solution.

01:21 So, formula is number of moles of solute divided by volume of solution and this volume of solution should be in litter.

01:42 Okay, if it is not in letter we have to convert that this is according to definition.

01:48 Now i can write that number of moles, so that's equal to molarity multiplied by volume.

02:03 So we will apply this relation here.

02:06 First of all in a part, so we have nacl.

02:16 So, number of moles of nacl.

02:34 So see, first of all, since i have nacl, so what will happen that it will dissociate into the solution.

02:45 So i have nacl and it will dissociate into na positive plus cl negative ion.

02:50 So here you can see that one mole of nacl that gives one mole of nacl that gives one mole of n a positive ion right and one mole of c l negative ion so this means that number of moles of n c l so that's equal to n a positive ion okay so that will be given by molarity multiplied by volume molarity we have given 0 .200 molar multiplied by 0 .270 letter.

03:45 So that's equal to 0 .04 mole...

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