Verify the conservation of mass law using the molar masses...

Verify the conservation of mass law using the molar masses of reactants and products for each substance in the following balanced equations: (a) $\mathrm{P}_{4}(\mathrm{~s})+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{P}_{2} \mathrm{O}_{3}(\mathrm{~s})$ (b) $\mathrm{P}_{4}(\mathrm{~s})+5 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{P}_{2} \mathrm{O}_{5}(\mathrm{~s})$

Verify the conservation of mass law using the molar masses of reactants and products for each substance in the following balanced equations:
(a) $\mathrm{P}_{4}(\mathrm{~s})+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{P}_{2} \mathrm{O}_{3}(\mathrm{~s})$
(b) $\mathrm{P}_{4}(\mathrm{~s})+5 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{P}_{2} \mathrm{O}_{5}(\mathrm{~s})$

Key Concepts

Conservation of Mass

This principle states that in a chemical reaction, matter is neither created nor destroyed. The total mass of reactants must equal the total mass of products, meaning the number and type of atoms remains consistent throughout the reaction.

Balanced Chemical Equations

A balanced chemical equation has equal numbers of each type of atom on the reactant and product sides, ensuring that the conservation of mass is satisfied. The stoichiometric coefficients indicate the relative amounts of each substance involved in the reaction.

Stoichiometry

Stoichiometry involves using the ratios between reactants and products in a balanced chemical equation to calculate the amounts (in moles or mass) of substances consumed and produced in a reaction. It bridges the gap between the qualitative chemical equation and quantitative measurement.

Molar Mass

Molar mass is the mass of one mole of a substance, expressed in grams per mole. It allows conversion between the mass of a substance and the number of moles, which is essential for verifying that the total mass remains the same on both sides of a reaction according to the law of mass conservation.

Transcript

00:01 In this question, we need to verify the law of conservation of mass.

00:05 Now, if we have a look at this equation in number a, the stoichiometric coefficients tell us that the ratio of the various substances are 1, 2, 3 to 2, which then also indicates the specific mole ratio for this reaction.

00:28 So it's in the ratio.

00:29 The mole ratio is 1, 2, 3, 2 .2.

00:38 In order to verify the law of conservation of mass, we have to calculate the masses of the reactants and then compare the sum thereof with the mass of the product.

00:52 Now, we know that we can calculate mass by multiplying the number of moles with molar mass.

00:59 So because we're working with a mole ratios here, we can use those ratios as number of moles.

01:08 I've pre -calculated the molar mass of each one of the substances just to save some time.

01:15 And you should know how to do this.

01:19 So just to recap that, in order, for instance, to calculate the molar mass of oxygen, i just take all the atoms, or then the oxygen gas, o2, i just take all the atoms involved and add the atomic mass of all those atoms.

01:35 So in order to calculate the molar mass of oxygen gas, diatomic oxygen gas, o2, that would be 16 plus 16.

01:48 For p205, it would be two times the atomic mass of phosphorus plus 5.

01:55 5 times the atomic mass of oxygen and so forth.

01:59 Right.

02:00 So in number a, in order to verify the law of conservation of mass, we are going to calculate the sum of the mass of the reactants first, and then compared to the mass of the product.

02:16 So here we have 1 mole of phosphorus, times the molar mass, which is 1 .23 .90 grams per mole.

02:37 And we will add to that three times the molar mass of oxygen, which is 32 .00.

02:48 I'm just going to add the units here so that you can see how they cancel out.

02:53 So it's just for this time...

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