4B1 Balancing Equations Flashcards
Balance chemical equations for various reaction types, including simple and oxidation-reduction reactions.
What does the law of conservation of matter state?
Matter cannot be created or destroyed; it can only be rearranged.
This means every molecule in a reaction must be accounted for.
Define:
balanced chemical equation
An equation showing the ratio of reactants and products with an equal number of atoms for each element on both sides of the equation.
Balancing ensures the law of conservation of matter is followed.
What is a word equation?
An equation that uses names of chemicals instead of formulas.
Example: glucose + oxygen → carbon dioxide + water.
Converting a word equation to a formula equation is the first step in balancing.
How do you convert a word chemical equation into a formula?
By writing the chemical symbols for each reactant and product involved in the reaction.
Example: Sodium is Na, Water is H₂O.
Fill in the blank:
The number written before a chemical in an equation is called a ______.
coefficient
Coefficients indicate how many molecules or moles of a substance participate in the reaction.
True or False:
Subscripts in chemical formulas can be changed when balancing chemical equations.
False
Only coefficients can be adjusted when balancing equations; changing subscripts alters the identity of the molecules involved.
Subscripts define the compound’s composition and cannot be modified without changing the reaction.
How are the coefficients used in balancing chemical equations?
They are used to adjust the number of molecules to ensure that each element has the same number of atoms on both sides of the equation.
They multiply the number of atoms in a molecule without changing the molecule’s identity.
List five steps to balance a chemical equation.
- Change a word equation into a formula.
- Balance single-molecule atoms one at a time.
- Balance non-H/O atoms.
- Balance H and O.
- Count atoms to verify balance.
This sequence minimizes trial and error and ensures accuracy in balancing.
How do you check if a chemical equation is balanced?
Count the number of atoms for each element on both sides and ensure they are equal.
Which atoms are typically balanced last in chemical equations?
Hydrogen and oxygen atoms.
These atoms are often present in multiple compounds, making them easier to balance after other atoms.
What is the purpose of balancing non-H/O atoms before H and O?
It simplifies the balancing process by addressing elements that are less likely to be in multiple compounds first.
This reduces the complexity of balancing elements like hydrogen and oxygen.
Fill in the blank:
In the reaction of sodium and water, the balanced equation is 2Na + 2H₂O → _______.
2NaOH + H₂
This reaction balances sodium, hydrogen, and oxygen atoms to comply with the conservation law.
Fill in the blank:
In the potassium and carbon dioxide reaction, the balanced equation is 2K + CO₂ → _______.
K₂CO₃
This balances potassium, carbon, and oxygen atoms in the reaction.
True or False:
A balanced chemical equation always uses whole number coefficients.
True
Whole numbers ensure the reaction represents physical reality since partial molecules do not exist.
What is the relationship between coefficients and moles in a balanced equation?
Coefficients indicate the mole ratio of reactants and products in the reaction.
This ratio helps predict quantities involved in a chemical reaction.
Define:
oxidizing agent
A compound that accepts electrons, decreasing its oxidation state.
Oxidizing agents are also known as oxidants or oxidizers.
Define:
reducing agent
A compound that donates electrons, increasing its oxidation state.
Reducing agents are also known as reductants.
What happens to the oxidizing agent in a reaction?
It gets reduced.
The oxidizing agent accepts electrons, becoming reduced in the process.
What happens to the reducing agent in a reaction?
It gets oxidized.
The reducing agent donates electrons, becoming oxidized in the process.
List four examples of oxidizing agents.
- Oxygen
- Ozone
- Halogens
- Sulfuric acid
These compounds can accept electrons and oxidize other substances.
List four examples of reducing agents.
- Sodium
- Magnesium
- Aluminum
- Hydrogen
These compounds readily donate electrons to reduce other substances. These tend to be atoms with low electronegativity, low oxidation states, or a large atomic radius.
True or False:
An oxidizing agent releases electrons.
False
An oxidizing agent accepts electrons.
True or False:
A reducing agent gains electrons.
False
A reducing agent loses electrons.
How can an oxidizing agent release oxygen?
By transferring oxygen to another compound.
This process is one way oxidizing agents facilitate oxidation.
How does a reducing agent release hydrogen?
By transferring hydrogen to another compound.
This is one method by which reducing agents facilitate reduction.
What is the term for a reaction where oxidation and reduction occur simultaneously?
A redox reaction
Redox reactions involve both oxidation and reduction processes occurring together.
What are the four types of redox reactions?
- Combination
- Decomposition
- Combustion
- Displacement
These reaction types involve changes in oxidation states of compounds.
Which side of an oxidation half-reaction shows electrons?
The right (product) side.
In oxidation, electrons are lost and appear on the product side of the equation.
Which side of a reduction half-reaction shows electrons?
The left (reactant) side.
In reduction, electrons are gained and appear on the reactant side of the equation.
How do you identify the oxidizing agent in a reaction?
Look for the compound with a decrease in oxidation state.
The oxidizing agent is reduced in the process.
How do you identify the reducing agent in a reaction?
Look for the compound with an increase in oxidation state.
The reducing agent is oxidized in the process.
What happens to the oxidation number of a reducing agent?
It increases.
The reducing agent donates electrons, increasing its oxidation state.
What happens to the oxidation number of an oxidizing agent?
It decreases.
The oxidizing agent gains electrons, decreasing its oxidation state.
True or False:
Redox reactions always involve both an oxidizing and reducing agent.
True
Oxidation and reduction processes are inseparable in redox reactions.
What is a combination reaction?
A reaction where two compounds combine to form one compound.
Example: 2H₂ + O2 → 2H₂O
What is a decomposition reaction?
A reaction where one compound breaks down into two compounds.
Example: NaCl → Na + Cl
What is a combustion reaction?
A reaction where an organic fuel reacts with oxygen to produce water and carbon dioxide.
Example: CH₄ + O₂ → CO₂ + H₂O
What is a displacement reaction?
A reaction where elements in two compounds swap places to form two new elements.
Example: Zn + CuCl₂ → ZnCl₂ + Cu
What is the oxidation half-reaction?
A half reaction that shows only the process of oxidation.
It does not include the oxidizing agent, which is assumed.
What is the reduction half-reaction?
A half reaction that shows only the process of reduction.
It does not include the reducing agent, which is also assumed.
How can you tell if a reaction is not a redox reaction?
If only one compound changes oxidation state without involving other compounds.
For example, in HCl + NaOH → H₂O + NaCl, only one compound changes.
