Write a balanced chemical equation for each of the following.
aqueous hydrogen chloride reacts with oxygen gas to form chlorine gas and liquid water.
liquid octane reacts with oxygen gas to form carbon dioxide gas and water vapor.
nitric oxide gas reacts with hydrogen gas to form ammonia gas and water vapor.
solid iron(iii) oxide reacts with carbon monoxide gas to form solid iron and carbon dioxide gas.

These are four questions and four complete answers

Since the answer is over 5,000 characters, the full answers are in the attached file.

Answers:

A) 4HCl (aq) + O₂(g) → 2Cl₂ (g) + 2H₂O (l)

B)  C₈H₂₀ (l) + 13O₂(g) → 8CO₂ (g) + 10H₂O (g)

C) 2NO (g) + 5H₂(g) → 2NH₃ (g) + 2H₂O (g)

D) Fe₂O₃ (s) + 3CO(g) → 2Fe (s)  + 3CO₂ (g)

Explanation:

A) Aqueous hydrogen chloride reacts with oxygen gas to form chlorine gas and liquid water.

1) Word equation:

Aqueous hydrogen chloride + oxygen gas → chlorine gas + liquid water

2) Chemical equation:

HCl (aq) + O₂(g) → Cl₂ (g) + H₂O (l)

3) Explanation of each term:

       *   The most electronegative element (Cl) is written to the right, and the least electronegative element (H) is written to the left.

       *  The abbreviation aq inside the parenthesis is used to describe the aqueous phase of the compound.

        * Oxygen is a diatomic molecule, so you use the subscript 2 to indicate the two atoms in the molecule.

        * The abbreviation (g) indicates the gas phase.

        * Chlorine is a diatomic gas, so you use the subscript 2 to indicate the two atoms in the molecule.

        * The abbreviation (g) indicates the gas phase.

        * The most electronegative element (O) is written to the right and the least electronetative element (H) is written to the left.

        * The subscript 2 next to H indicates that there are two atoms of hydrogen, while the lack of subscript next to O indicates that there is one atom of oxygen, in each molecule of water.

       * The abbreviation (l) indicates the liquid phase of water.

4) Balancing

To obey the mass conservation law, the number of each kind of atoms in the reactant side must equal the number of the same kind of atom in the product side. Hence, you have to introduce the necessary coefficients to balance the equation:

Count each kind of atoms on each side to check the equation is balanced:

Element         left side         right side

H                      4                    2×2 = 4

Cl                     4                    2×2 = 4

O                      1×2 = 2           2×1 = 2

Conclusion: the balanced chemical equation is

B) Liquid octane reacts with oxygen gas to form carbon dioxide gas and water vapor.

1) Word equation:

liquid octane + oxygen gas → carbon dioxide gas + water vapor

2) Chemical equation:

C₈H₂₀ (l) + O₂(g) → CO₂ (g) + H₂O (g)

3) Explanation of each term:

       *  This is an organic compound. An alkane. This name follows IUPAC rules.

       *  The abbreviation (l) describes the liquid phase of the compound.

        * Oxygen is a diatomic molecule, so you use the subscript 2 to indicate the two atoms in the molecule.

        * The abbreviation (g) indicates the gas phase.

        * Oxygen, O, is the most electronegative, and carbon (C) is the least electronegative.

       * The subscript 2 next to O atom, indicates that there are two atoms of oxygen in the molecule. There is only one atom of carbon (no subscript is added).

        * The abbreviation (g) indicates the gas phase.

        * The most electronegative element (O) is written to the right and the least electronetative element (H) is written to the left.

        * The subscript 2 next to H indicates that there are two atoms of hydrogen. The lack of subscript next to O indicates that there is one atom of oxygen, in each molecule of water.

       * The abbreviation (g) indicates the vapor (gas) phase of water.

4) Balancing

To obey the mass conservation law, the number of each kind of atoms in the reactant side must equal the number of the same kind of atom in the product side. Hence, you have to introduce the necessary coefficients to balance the equation:

Count each kind of atoms on each side to check the equation is balanced:

Element         left side         right side

C                        8                      8

H                      20                   10×2 = 20

O                      13×2 = 26        8×2 + 10 = 26

Conclusion: the balanced chemical equation is

Since the answer is over 5,000 characters the next answers are in the attached file.

Balanced chemical equation  :

1. 4HCl (aq) + O₂ (g) ⇒ 2Cl₂ (g) + 2H₂O (l)

2. C₈H₂₀ (l) + 13O₂ (g) ⇒ 8CO₂ (g) + 10H₂O (g)

3. 2NO (g) + 5 H₂ (g) ⇒ 2NH₃ (g) + 2H₂O (g)

4. Fe₂O₃ (s) + 3CO (g) ⇒ 2Fe (s) + 3CO₂ (g)

Equalization of chemical reactions can be done using variables. Steps in equalizing the reaction equation:

For gas combustion reaction which is a reaction of hydrocarbons with oxygen produces CO₂ and H₂O (water vapor). can use steps:

Balancing C, H and the last O

Suppose we give a coefficient of 1 for HCl

HCl (aq) + aO₂ (g) ⇒ bCl₂ (g) + cH₂O (l)

number of H atoms: left 1, right 2c -> 2c = 1-> c = 1/2

number of Cl atoms: left 1, right 2b ---> 2b = 1 > b = 1/2

number of O atoms: left 2a, right c ---> 2a = c ---> 2a = 1/2 ---> a = 1/4

the reaction coefficient becomes:

HCl (aq) + 1 / 4O₂ (g) ⇒ 1 / 2Cl₂ (g) + 1 / 2H₂O (l) x 4

4HCl (aq) + O₂ (g) ⇒ 2Cl₂ (g) + 2H₂O (l)

Suppose we give a coefficient of 1 for C₈H₂₀

 C₈H₂₀ (l) + aO₂ (g) ⇒ bCO₂ (g) + cH₂O (g)

number of C atoms: left 8, right b ---> b = 8

number of H atoms: left 20, right 2c -> 2c = 20 -> c = 10

number of O atoms: left 2a, right 2b + c ---> 2a = 2b + c ---> 2a = 2.8 + 10 ---> 2a = 26 ---> a = 13

the reaction coefficient becomes:

C₈H₂₀ (l) + 13O₂ (g) ⇒ 8CO₂ (g) + 10H₂O (g)

Let's say we give a coefficient of 1 for NH₃

 aNO (g) + bH₂ (g) ⇒ NH₃ (g) + cH₂O (g)

number of N atoms: left a, right 1 ---> a = 1

number of O atoms: left a, right c ---> a = c = 1

number of H atoms: left 2b, right 3 + 2c -> 2b = 3 + 2.1 ---> 2b = 5 -> b = 5/2

the reaction coefficient becomes:

NO (g) +5/2 H₂ (g) ⇒ NH₃ (g) + H₂O (g) x2

2NO (g) +5 H₂ (g) ⇒ 2NH₃ (g) + 2H₂O (g)

Let's say we give a coefficient of 1 for Fe₂O₃

 Fe₂O₃ (s) + aCO (g) ⇒ bFe (s) + cCO₂ (g)

number of Fe atoms: left 2, right b ---> b = 2

number of O atoms: left 3 + a, right 2c ---> 3 + a = 2c

number of C atoms: left a, right c -> a = c -> we put in the equation the number of atoms O

3 + c = 2c ---> 3 = c = a

the reaction coefficient becomes:

 Fe₂O₃ (s) + 3CO (g) ⇒ 2Fe (s) + 3CO₂ (g)

the combustion of octane in gasoline

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hydrogen and excess oxygen

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the answer is d. 74.02