A chemical equation is a symbolic representation of a chemical reaction using chemical formulas and symbols.
What are the two main parts of a chemical equation?
The two main parts of a chemical equation are the reactants and the products.
Where are the reactants written in a chemical equation?
Reactants are written on the left side of the chemical equation.
Where are the products written in a chemical equation?
Products are written on the right side of the chemical equation.
What does the arrow (→) indicate in a chemical equation?
The arrow (→) indicates the direction of the reaction, or “yields” or “reacts to form.”
What are coefficients in a chemical equation?
Coefficients are numbers placed in front of chemical formulas to balance the equation.
Why is it necessary to balance a chemical equation?
It is necessary to balance a chemical equation to obey the law of conservation of mass.
What does the state symbol (s) represent?
The state symbol (s) represents a solid.
What does the state symbol (g) represent?
The state symbol (g) represents a gas.
What does the state symbol (aq) represent?
The state symbol (aq) represents an aqueous solution (dissolved in water).
What is the qualitative aspect of a chemical equation?
The qualitative aspect identifies the substances involved in the reaction and their physical states.
What is the quantitative aspect of a chemical equation?
The quantitative aspect gives the numerical relationships between reactants and products.
What is stoichiometry?
Stoichiometry is the calculation of quantitative relationships in chemical reactions.
What is a mole ratio?
A mole ratio is the ratio of moles of reactants and products from the balanced chemical equation.
How are mole ratios obtained from a chemical equation?
Mole ratios are obtained from the coefficients in the balanced chemical equation.
What is the molar volume of a gas at room temperature and pressure (RTP)?
The molar volume of a gas is 24 dm³ mol⁻¹ at RTP.
What is the molar volume of a gas at standard temperature and pressure (STP)?
The molar volume of a gas is 22.4 dm³ mol⁻¹ at STP.
In the balanced equation 2H₂(g) + O₂(g) → 2H₂O(g), what is the mole ratio of H₂ to O₂?
The mole ratio of H₂ to O₂ is 2:1.
What is the role of molar mass in stoichiometric calculations?
The molar mass converts mass to moles and vice versa.
What is the first step in balancing a chemical equation?
The first step in balancing a chemical equation is to write the correct chemical formulas for all reactants and products.
Explanation Questions
Explain the significance of using coefficients in balancing chemical equations.
Coefficients are used to balance the number of atoms of each element on both sides of the equation, ensuring the conservation of mass.
Why is it important to not alter chemical formulas when balancing equations?
Changing chemical formulas alters the identities of the substances involved, whereas balancing is meant to adjust quantities while maintaining the correct chemical formulas.
Describe how to balance a chemical equation that involves polyatomic ions, such as sulphate or nitrate.
Balance polyatomic ions as a single unit if they remain unchanged in the reaction, adjusting the number of units by adding appropriate coefficients.
Explain why state symbols are important in a chemical equation.
State symbols indicate the physical state of the substances, giving additional details that can be important in interpreting chemical processes.
How does the qualitative information in a chemical equation differ from the quantitative information?
Qualitative information identifies the reactants and products, while quantitative information provides the numerical relationship between reactants and products based on the mole concept.
Describe the steps needed for a typical stoichiometry calculation.
1. Write the balanced chemical equation. 2. Convert given quantities to moles. 3. Use the mole ratio to find the moles of the required substance. 4. Convert moles to the desired units (mass, volume, etc.).
Explain how the concept of moles relates to coefficients in a balanced chemical equation.
The coefficients in a balanced chemical equation represent the mole ratio of the substances involved in the reaction, allowing for quantitative calculations.
Describe how to use the molar volume of a gas in stoichiometric calculations.
Use molar volume (24 dm³ mol⁻¹ at RTP or 22.4 dm³ mol⁻¹ at STP) to convert the volume of a gas to moles or vice versa at a given temperature and pressure.
Explain the difference between a balanced and unbalanced chemical equation.
A balanced chemical equation has the same number of each type of atom on both sides of the equation, whereas an unbalanced equation does not. This ensures the conservation of mass.
Using an example, explain how stoichiometry helps in predicting the amount of product formed given the amount of reactant.
Consider the equation, **2H₂(g) + O₂(g) → 2H₂O(g)**. If you start with **4 moles of H₂**, using the mole ratio of **H₂:H₂O** which is **2:2 or 1:1**, you can determine that **4 moles of H₂O** will be formed.