Defenitions Flashcards
(31 cards)
What is a physical change?
No new substance formed (temporary)
Physical changes can often be reversed, such as melting or freezing.
What is a chemical change?
New substance formed (permanent)
Chemical changes typically involve a transformation where the original substances lose their chemical properties.
Define a chemical reaction.
A process where new substances are formed
Chemical reactions can occur in various environments and conditions, often involving energy changes.
List signs of a chemical reaction.
- Change in state
- Change in colour
- Gas is produced
- Change in temperature
These signs can indicate a chemical reaction but are not definitive proof on their own.
What is a chemical equation?
Shows a chemical reaction using symbols and formulas
Chemical equations represent the reactants and products in a reaction.
Provide an example of a chemical equation.
Magnesium + Oxygen → Magnesium Oxide
This equation illustrates the combination of magnesium and oxygen to form magnesium oxide.
What is a balanced chemical equation?
Same number of atoms on both sides
Balancing chemical equations is essential to comply with the law of conservation of mass.
Give an example of a balanced chemical equation.
Zn + H₂SO₄ → ZnSO₄ + H₂
This equation balances zinc and sulfuric acid to produce zinc sulfate and hydrogen.
What is a combination reaction?
Two or more reactants → One product
Combination reactions are fundamental in various chemical processes, including synthesis.
Provide an example of a combination reaction.
CaO + H₂O → Ca(OH)₂ (Slaked lime)
This reaction is exothermic and is used in whitewashing to create a shiny layer of calcium carbonate.
What characterizes an exothermic reaction?
Gives off heat
Exothermic reactions release energy, often in the form of heat, to the surroundings.
What happens to white silver chloride in sunlight?
It turns grey due to the decomposition into silver and chlorine by light.
What type of reaction is involved in black and white photography?
The decomposition of silver chloride.
Define a displacement reaction.
A chemical reaction in which a more reactive element displaces a less reactive element from its compound.
What elements can participate in displacement reactions?
Both metals and non-metals.
Provide an example of a displacement reaction involving iron and copper sulfate.
Fe (s) + CuSO4 (aq) → FeSO4 (g) + Cu (s)
Provide an example of a displacement reaction involving lead and copper chloride.
Pb (s) + CuCl2 (aq) → PbCl2 (aq) + Cu (s)
What is a double displacement reaction?
A reaction where two compounds react, and the cations and anions switch places, forming two new compounds.
What is another name for a double displacement reaction?
Double replacement reaction or metathesis.
Define a redox reaction.
A chemical reaction that involves a transfer of electrons between two species.
What occurs during oxidation?
Gain of oxygen or loss of hydrogen.
What occurs during reduction?
Gain of hydrogen or loss of oxygen.
What is an oxidizing agent?
A substance that gives oxygen or gains hydrogen.
What is the role of an oxidizing agent?
It is reduced itself and oxidizes other substances.
