Challenge For each of the following, balance the chemical equation; interpret the equation in te

Challenge For each of the following, balance the chemical...

Key Concepts

Mole Concept

The mole concept is a fundamental unit in chemistry that represents a specific number (Avogadro's number) of particles, such as atoms, ions, or molecules. This concept provides a bridge between the atomic scale and macroscopic quantities, allowing for the conversion between the number of particles and the measurable masses involved in chemical reactions.

Stoichiometry

Stoichiometry is the quantitative study of reactants and products in a chemical reaction. It uses the coefficients from a balanced chemical equation to determine the ratios in which substances react and are formed, linking the counts of particles, the number of moles, and the masses involved in the reaction.

Relationship Between Particles, Moles, and Mass

Understanding the relationship between particles, moles, and mass is essential in chemistry. This concept involves using the mole as a counting unit, where the number of particles is related to the number of moles via Avogadro's number, and then linking moles to mass using the substance’s molar mass. This integrated approach is vital for interpreting chemical equations in terms of the actual amounts of substances involved.

Balancing Chemical Equations

Balancing chemical equations involves adjusting the coefficients of the reactants and products so that the number of atoms of each element is the same on both sides of the equation. This procedure ensures that the equation complies with the fundamental principle of matter conservation, meaning that atoms are neither created nor destroyed during a chemical reaction.

Law of Conservation of Mass

The law of conservation of mass states that the mass of the products in a chemical reaction must equal the mass of the reactants. In chemical equations, this concept is reflected by ensuring that the total count of each type of atom is consistent on both sides of the equation, confirming that mass is conserved during the reaction.

Transcript

00:01 In this exercise, we need to balance two equations and then interpret the equations in terms of particles, moles, and mass.

00:22 And then we need to verify the law of mass conservation.

00:35 The first equation is the reaction of sodium in the solid state plus water in the liquid state, producing sodium hydroxide in solution plus hydrogen gas.

01:04 Okay? so this reaction is a redox reaction, and you can just say that by looking at the transition of sodium from an oxidation state of zero to positive one.

01:17 So sodium is getting oxidized.

01:20 And that's the first half equation we're going to write here.

01:23 Okay.

01:24 So sodium gets oxidized.

01:28 To sodium osplif one and then in order to balance the charges we need to add one electron here and we get zero and zero charge on each side of the equation now the reduction reaction the reduction reaction is the reduction of the hydrogen in water to gas hydrogen okay um first, in order to balance oxygens and hydrogens, in this reaction we need to use hydroxide ions and water.

02:10 Why hydroxide ions? because this reaction is taking place in a basic environment.

02:15 And you can say that by looking at the production of hydroxide ions.

02:19 So first to balance the oxygen, we need to add a molecule of water here.

02:27 By doing so we're introduced sorry we need to add a hydrogen ion a hydroxide ion because we are in again we are in a basic solution so to balance the oxygen we need to add a hydroxide ion by doing so we're introducing a hydrogen here and we are on balancing the hydrogens so to rebalance hydrogen we put the coefficient two and then, because now we have two oxygens, we have to put a coefficient two in front of water.

03:07 Now we've verified and we have four hydrogens, four hydrogens, two oxygen, two oxygens.

03:13 Now, the only thing we need to do is to balance the charges.

03:19 Zero here, two negative here.

03:21 We add two electrons here.

03:24 Now, before we add the half equations, we need to multiply the oxidation, half reaction, half reaction by two electrons.

03:31 So that we can get two electrons.

03:33 Okay, and then the rebalanced oxidation reaction is two sodium, producing two sodium ions plus two electrons.

03:46 And now we are ready to add these half equations.

03:51 Electrons cancel, and then we have two sodium in the soil state plus two water in the liquid state, producing, these two sodium ions combined with these two hydroxide ions to produce two sodium hydroxide plus in solution plus hydrogen gas now let's interpret this reaction we have two atoms of sodiums reacting with two molecules of water this is the interpretation in terms of particles of particles okay two molecules of water producing two hydrogen ions because it's in solution plus two hydroxide ions plus one molecule of hydrogen now the interpretation in terms of moles okay is two moles of sodium react with two moles of water to produce two moles of sodium hydroxide, two moles of sodium hydroxide, plus one mole of hydrogen.

05:51 Now the interpretation in terms of mass, two sodium, we multiply two by the atomic weight of sodium, which is 23, plus two times.

06:08 So two, two, times the atomic mass of sodium, which is 23.

06:14 Two times the molar mass of water, which is 2 plus 16, 18, producing 2 times the molar mass of sodium hydroxide, which is 23 plus 16 plus 1 is 40, plus 1 times the molar mass of hydrogen, which is 2 times 1.

06:50 So we have here, 46 grams of sodium reacts with 36 grams of water to produce 82 grams of sodium of sodium, plus 2 grams of hydrogen.

07:10 Now let's verify the law of mass conservation.

07:14 For that, the total mass of the reactor must be equal to the total mass of the products.

07:19 46 plus 36 is 84.

07:26 Sorry this is 80 2 times 40 is 80 okay 46 plus 36 is 82 and 82 plus 2 is 82 next equation we have solid zinc reacting with nitric acid in solution to produce zinc nitrate in solution plus dinitrogen oxide gas plus water again this is a redox reaction and we know that just by looking at the transition of zinc from an oxidation state of zero to an oxidation state of positive two so let's first write down the oxidation half reaction which is the oxidation of zinc to zinc two plus and then to balance the charges we add to alex here.

08:58 Now a reduction reaction.

09:01 Nitrate is converted into two nitrate from here plus dinitrogen oxide.

09:15 First let's balance the nitrogens.

09:17 We have two and two, four.

09:20 We need a four here.

09:22 Now we balance the oxygen.

09:24 12 and we have six and one seven, so we need five.

09:28 By introducing five water, by using five water, we're introducing 10 hydrogen ions...