Chemistry Revision Flashcards
(29 cards)
What are the signs of a chemical change
Colour change
Odour
Change in temperature
Evolution of gas (formation of bubbles)
Precipitate (formation of a solid)
What is the law of conservation of mass
Matter can not be created nor destroyed
What is an endothermic reaction
Reaction that absorbs heat from surrounding
Exothermic
Reaction that releases heat
What causes endothermic reactions
More energy stored in the product
What causes exothermic reaction
More energy stored in the bonds
Name types of energy
Heat
Kinetic
Light
Potential
What is the law of conservation of energy
Energy can not be created or destroyed only transferee from one type to another
What is energy efficiency
A measure of how much input energy is converted into useful output
How to calculate energy efficiency
Useful energy over energy input times 100
Name some renewable energy sources
Hydro
Solar
Wind
What are the Benefits of renewable energy
Cleaner enviorment
Less carbon emissions
Uses less water
Cons of renewable energy
Not always reliable
What is electricity
Electricity is a phenomenon involved with moving or stationary electric charges
What subatomic particles are in electricity
Electron
What is ac
Alternating currents. This is where electricity flows in both directions
What is DC
Direct current. This is where electricity flows in one direction
What is ohms law
That voltage(V) equals current(I) times resistance(R)
What is ohms law used for
To calculate the relationship between voltage,current and resistance in a circuit
What is a series circuit
A circuit that has 1 pathway that flows through 1 or more resistors
What is a parallel Circuit
A parallel circuit is a circuit that has to pathways so that the current divides. Voltage across the circuit is the same
Why do we use parallel circuits
it allows you to use switches and not affect the flow of electricity in other pathways
Why do we use series circuits
It allows us to turn one or more loads at the same time
What is a covalent bond
The sharing of electrons for stability in an atom
