Chapter 4: Changes in Matter Flashcards
(20 cards)
What is a physical change?
A change where the substance’s nature stays the same.
(Ex: melting, cutting)
What is a chemical change?
A change where a new substance is formed.
(Ex: burning, rusting)
What are signs of a chemical change?
Gas produced, heat/light emitted, colour change, precipitate formed.
What is a nuclear transformation?
A change in the nucleus that produces a new element and radiation.
What is the Law of Conservation of Mass?
The mass of the reactants equals the mass of the products in a chemical reaction.
MATH Q: If 15 g of HCl reacts with 25 g of Al to produce 29 g of AlCl₃, how much H₂ is released?
15 + 25 = 40 g → 40 - 29 = 11 g of H₂
What does a subscript in a chemical formula tell you?
The number of atoms of that element in a molecule.
(Ex: H₂O has 2 H, 1 O)
What does a coefficient tell you?
The number of molecules.
(Ex: 2 H₂O = 4 H atoms + 2 O atoms)
What is the rule for balancing chemical equations?
You can only change coefficients, NOT subscripts.
STEPS to balance:
1) Count atoms on both sides
2) Change coefficients
3) Repeat until balanced
4) Make sure all coefficients are whole numbers
BALANCE: N₂ + H₂ → NH₃
N₂ + 3H₂ → 2NH₃
What is an acid-base neutralization reaction?
Acid + Base → Water + Salt
How do you recognize an acid in a formula?
Starts with H.
(ex: HCl)
How do you recognize a base?
Ends with OH.
(ex: NaOH)
What are the products of HCl + NaOH?
H₂O + NaCl
What is a combustion reaction?
A reaction where fuel + oxygen produce CO₂, H₂O, and energy.
What are the 3 things needed for combustion?
- Oxygen
- Fuel
- Ignition temperature
What are the 3 types of combustion?
- Rapid
- Spontaneous
- Slow
What is cellular respiration?
Glucose + Oxygen → CO₂ + H₂O + Energy
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy
What is photosynthesis?
CO₂ + H₂O + Energy → Glucose + Oxygen
6CO₂ + 6H₂O + Energy → C₆H₁₂O₆ + 6O₂
