Physical and Chemical Changes Flashcards
What is a physical change?
A change where no new substance is formed.
How do you know is a physical change has taken place?
- there is a change of state
- there is a change in physical appearance
- a solid is dissolved in a liquid
- one mixture is separated from a mixture
What is a chemical change?
A change where at least one new substance is formed.
How do you know if a chemical change has taken place?
- a gas is produced
- a solid is formed
- there is a colour change
- significant change in temperature
- an odour is produced
What is the law of conservation of mass?
Mass is neither created nor destroyed in chemical reactions. In other words, the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction
What is an atom?
The smallest part of a chemical element that can exist.
What takes place in a chemical reaction?
element join with one another to create compounds, or the chemical binds of compounds are broken and rearranged.
What are everyday chemical reactions examples?
- iron rusting
- burning wood
- metabolism
- cooking an egg
- baking a cake
What is weathering?
Weathering refers to the wearing away of rocks or other substances into smaller pieces.
What is chemical weathering?
The wearing away of substances through chemical processes such as acid rain and rusting
What is the cause and effects of acid rain?
- raindrops can dissolve pollution like sulfuric dioxide in the air.
- this increases the acidity (sulfuric acid) of the rain.
- acid rain can dissolve some rocks such as limestone and marble which causes them to wear away.
- acid rain can also damage buildings, statues and plants, and increase the acidity of lakes and rivers.
What is a polymer and what are some common examples?
A polymer is a large molecule that is formed by combining many identical small molecules called monomers. Examples include:
- polyethylene (plastic)
- polystyrene
- protein
- starch
- cellulose
What are the properties and uses of polyvinyl chloride (PVC)
Properties: - stiff - strong - resists scratching - good chemical resistance - lightweight Can be used for: - electrical insulation - garden hoses - drainage and sewerage pipes - household guttering and downpipes - arts and crafts glue
What are the good and bad of researching polymers?
Pros: provide us with alternative materials - allows metals to be used in different areas - relatively cheap to produce Cons: - most require the use of petrochemicals - disposal of waste products - not all are recyclable - increased landfill
What is pharmaceutical and provide examples
A pharmaceutical is a compound that is manufactures for use as a medicinal drug. Examples include:
- aspirin (pain relief and blood thinner)
- clotrimazole (anti-fungal)
- amoxicillin (antibiotic, kills bacteria)
- ibuprofen (anti-inflammatory, pain relief)
