Chemistry Chapter 1: Chemical Equations

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Questions and Answers

What is the initial number of iron atoms in the reactants of the given chemical equation?

1 (correct)

How many total hydrogen atoms are present in the products of the balanced equation?

8 (correct)

Which method is used to balance the given chemical equation?

Algebraic Method

Hit-and-Trial Method (correct)

Redox Method

Stoichiometric Method

In the balanced equation 3Fe + 4H2O → Fe3O4 + 4H2, what is the physical state information provided?

No information on physical states Signup and view all the answers

What is the number of water molecules present in the reactants for the final balanced equation?

4 Signup and view all the answers

To balance iron (Fe) in the equation 3Fe + 4H2O → Fe3O4 + 4H2, how many iron atoms are needed on the reactant side?

3 Signup and view all the answers

What is the final balanced equation represented in the content?

3Fe + 4H2O → Fe3O4 + 4H2 Signup and view all the answers

Which element is stated as the last to be balanced in the given equation?

Iron Signup and view all the answers

What does the symbol (aq) indicate in a chemical equation?

The substance is dissolved in water. Signup and view all the answers

In the equation 3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g), what does the (g) next to H2O signify?

Water is used as steam. Signup and view all the answers

Which of the following conditions is commonly indicated above or below the arrow in a balanced chemical equation?

Reaction conditions such as temperature or pressure. Signup and view all the answers

What is the primary reason for balancing chemical equations?

To comply with the law of conservation of mass. Signup and view all the answers

What is the correct balanced equation for the reaction of hydrogen and chlorine to form hydrogen chloride?

H2 + Cl2 → 2HCl Signup and view all the answers

If the balanced equation for sodium reacting with water is written as 2Na + 2H2O → 2NaOH + H2, what does the coefficient '2' before Na and H2O indicate?

Two moles of sodium react with two moles of water. Signup and view all the answers

In the reaction 6CO2(aq) + 12H2O(l) → C6H12O6(aq) + 6O2(aq) + 6H2O(l), what is the role of chlorophyll?

It acts as a catalyst for the reaction. Signup and view all the answers

Which of the following correctly represents the physical state of barium sulfate in the equation BaCl2 + Al2(SO4)3 → 3BaSO4 + 2AlCl3?

BaSO4(s) - solid Signup and view all the answers

What is a skeletal chemical equation?

A representation of a chemical reaction that is unbalanced. Signup and view all the answers

Which law is crucial for balancing a chemical equation?

Law of Conservation of Mass Signup and view all the answers

In the reaction Zn + H2SO4 → ZnSO4 + H2, how many hydrogen atoms are present in the products?

2 Signup and view all the answers

What should be done first when balancing the equation Fe + H2O → Fe3O4 + H2?

Draw boxes around each formula. Signup and view all the answers

How many sulfur atoms are present in the equation Zn + H2SO4 → ZnSO4 + H2?

1 Signup and view all the answers

Why do we need to balance a skeletal chemical equation?

To ensure the mass is conserved. Signup and view all the answers

In the balanced equation Zn + H2SO4 → ZnSO4 + H2, how are the oxygen atoms counted?

Count 4 in H2SO4 and 4 in ZnSO4. Signup and view all the answers

How many total atoms are present in the reactants of the equation Fe + H2O → Fe3O4 + H2?

5 Signup and view all the answers

Study Notes

Chemical Equations

A skeletal chemical equation is unbalanced, indicating unequal mass on both sides.
The law of conservation of mass states that mass cannot be created or destroyed in a reaction.
Total mass of products must equal the total mass of reactants, reflecting equal atom counts for each element.

Balancing Chemical Equations

Example of a balanced equation:
Zn + H₂SO₄ → ZnSO₄ + H₂
- Atom count: Zn (1), H (2), S (1), O (4) is consistent on both sides.
To balance an equation, the number of each type of atom must match on the reactant and product sides.

Steps to Balance Equations

Draw boxes around formulas to isolate elements.
For the equation Fe + H₂O → Fe₃O₄ + H₂:
- Start with element counts: Fe (1), O (1), H (2) on LHS versus Fe (3), O (4), H (2) on RHS.
- Initial step for physical states includes (g), (l), (aq), and (s) for gaseous, liquid, aqueous, and solid states respectively.

Example of Balancing

Begin with the partly balanced equation:
3Fe + 4H₂O → Fe₃O₄ + 4H₂
Verify atom counts to ensure balance:
- Fe: LHS (3), RHS (3)
- H: LHS (8), RHS (8)
- O: LHS (4), RHS (4)

Including Physical States

A balanced equation's clarity increases by specifying reactant and product states.
Example with physical states:
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)

Techniques for Balancing

Hit-and-trial method emphasizes using the smallest whole number coefficients to achieve balance.
Ensure all elements are checked after each adjustment to maintain equality across the equation.

Questions for Practice

Importance of cleaning magnesium before burning: Removes oxidation for accurate reaction.
Balanced equations for specified reactions:
- Hydrogen + Chlorine → Hydrogen chloride: H₂ + Cl₂ → 2HCl
- Barium chloride + Aluminum sulfate → Barium sulfate + Aluminum chloride: BaCl₂ + Al₂(SO₄)₃ → BaSO₄ + 2AlCl₃
- Sodium + Water → Sodium hydroxide + Hydrogen: 2Na + 2H₂O → 2NaOH + H₂

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Description

Test your understanding of chemical equations with this quiz covering skeletal and balanced chemical equations. You will be assessed on the law of conservation of mass and its implications in chemical reactions. Perfect for students revisiting basic chemistry concepts.