Chemical Equations- Flashcards
(18 cards)
What is a chemical reaction?
A process in which substances (reactants) change to form new substances (products) with different properties.
What is a chemical equation?
A symbolic representation of a chemical reaction using element symbols and formulas.
What are reactants and products?
Reactants are the starting substances; products are the new substances formed.
What does the arrow (→) in a chemical equation mean?
It means “yields” or “produces”; it separates reactants from products.
What is a synthesis (combination) reaction?
Two or more substances combine to form one product.
Example: A + B → AB
What is a decomposition reaction?
A single compound breaks down into two or more simpler substances.
Example: AB → A + B
What is a single displacement reaction?
One element replaces another in a compound.
Example: A + BC → AC + B
What is a double displacement reaction?
Two compounds exchange ions to form two new compounds.
Example: AB + CD → AD + CB
What is a combustion reaction?
A substance reacts with oxygen, releasing energy (heat/light).
Example: Hydrocarbon + O₂ → CO₂ + H₂O
Why must chemical equations be balanced?
To obey the Law of Conservation of Mass — matter is neither created nor destroyed.
What are coefficients in chemical equations?
Numbers placed in front of formulas to balance the equation.
Can subscripts be changed when balancing equations?
No, only coefficients can be changed.
What are the steps to balance a chemical equation?
-Write the correct formulas
-Count atoms on both sides
-Use coefficients to balance atoms
-Check your work
Balanced equation for:
H₂ + O₂ → H₂O
2H₂ + O₂ → 2H₂O
What do state symbols (s), (l), (g), and (aq) mean?
(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous (dissolved in water)
What is a word equation?
A chemical reaction written in words.
Example: Hydrogen + Oxygen → Water
What is a skeletal equation?
An unbalanced chemical equation using formulas.
What is the Law of Conservation of Mass?
Mass cannot be created or destroyed in a chemical reaction; total mass of reactants = total mass of products.
