Physical and Chemical Changes - 7.3 Chemical Reactions [ARCHIVE] Flashcards
What is produced during a chemical change?
New substances
How do explosions occur?
When combustion releases so much energy so quickly that an explosion occurs.
What do we use combustion for nowadays.
-To heat and cook
-Run cars
-To generate electricity in gas power stations
What is photosynthesis?
A series of chemical reactions that uses sunlight to convert water and carbon dioxide into oxygen gas, and form sugar called glucose.
What are common indicators of a chemical change?
- Permanent color change
- Gas release
- Precipitate formation
- Temperature change
- Light production.
How does a chemical change differ from a physical change?
A chemical change rearranges atoms, while a physical change does not.
Why do graphite and diamond have different properties?
They have different properties because the carbon atoms in each are arranged differently.
What is the key difference between water (H₂O) and hydrogen peroxide (H₂O₂)?
Water (H₂O) has two hydrogen atoms and one oxygen atom, while hydrogen peroxide (H₂O₂) has two of each, giving them different properties.
What is a chemical reaction?
The process of rearranging atoms to form new substances.
What are the reactants and products in a chemical reaction?
Reactants are the old substances, and products are the new substances formed.
What happens when magnesium burns in oxygen? (formula)
Magnesium + Oxygen → Magnesium Oxide
(releasing heat and light.)
What is produced when hydrogen gas reacts with chlorine gas?
Hydrogen chloride gas
Why is evaporation considered a physical change?
Because the water molecules rearrange but no new substance forms.
What is combustion?
A chemical reaction involving burning with oxygen to release heat and light.
What happens when methane burns in oxygen? (formula)
Methane + Oxygen → Carbon dioxide + Water vapor.
Why is combustion important in human development?
It has been crucial for…
- Cooking
- Heating
- Generating energy
Why does photosynthesis only occur in plants?
The chemical reaction requires chlorophyll (the chemical that makes leaves green).
What is respiration?
The process of obtaining energy from food, and can be thought as the opposite of photosynthesis.
What are some examples of chemical reactions in the atmosphere?
-Formation of holes in the ozone layer
-Smog from air pollution
What is chemical weathering?
The gradual breaking down of rocks due to reactions with chemicals in rainwater, hail, sleet e.t.c.
What does corrosive mean?
They can chemically dissolve many types of substances including some rocks and metals.
Over time, what can chemical weathering do?
Change the face of the Earth.
What is the word equation for Respiration?
glucose + oxygen → carbon dioxide + water + energy
