Acid reactions
What are two properties of acids and bases/alkalis?
Acids release H+ ions in solutions, they are bitter (lemon/vinegar), they are corrosive, they change universal indicator to orange/red pH1-6
Alkalines release OH-ions in solutions, they feel slippery like soap, they are caustic, they change universal indicator solution to blue/purple pH8-14
What is the difference between a cation and anion?
Cation are positive ions they have lost electrons
Anions are negative ions they have gained electrons
Define resistance, current and potential difference
Resistance the opposition to current flow
Current - the rate or speed that electons are moving
Potential difference - also called voltage - the electrical push in a circuit to move electrons
A student put 2 new and charged batteries in a torch, suggest two things that may be incorrect?
The batteries are put it in the opposite polarity +--+
The lamp filament is broken
Name 3 GHG
CO2
methane
nitrous oxide
water vapor
What is the common equation for neutralisation reaction?
acid + alkali yield salt + water
Lithium has an atomic mass of 7 and an atomic number of 3. How many neutrons does it have?
Atomic number = proton number
7= 3+ ____
Neutrons =4
Compare the inputs and outputs of motors and generators
Motor input is electricity output is spin/movement
Generator input is movement/turbine spin and output is electricity
A student set up a transformer circuit to see how the number of turns changed the output voltage.
They had a 9V battery, a primary coil with 10 windings and a secondary coil with 100 windings.
What did they expect to see?
Nothing, the battery is dc and transformers need AC
What is the benefit of the greenhouse effect and what is the consequence of the enhanced greenhouse effect?
Greenhouse effect is natural and necessary to maintain a stable climate on earth.
Too thick a greenhouse layer and heat is trapped in earth, global temp rise.....
rising sea levels - loss of habitat, changed floods/droughts
Adaptations of species - food shortage
What gas is given off in a metal acid reaction and how is it tested?
Hydrogen with a pop test
Group 8 or 0, the noble gases. They have full outer electron shells so they can't receive any more electrons and don't want to get rid of any electrons
What's the difference between a permanent and electromagnet? How can you increase the strength of an electromagnet?
Permanent always has magnetic properties
Electro needs power connected
Number of turns, diameter of the core and input voltage can increase the strength of an electromagnet
A student was over doing it in the combustion of steel wool prac and the power supply tripped. What caused this?
Too much current tripped the circuit breaker in the power supply
Name a device or devices that can reduce or sequest GHG emissions
Catalytic converters or scrubbers
Tree planting
Less fossil fuel burning - use of renewable energy supplies (solar, wind, hydro)
LED over incandescent
How can you test an unknown substance for its acidity?
Use pH paper or universal indicator solution
A radioisotope has a half life of 3 days.
Define isotope
And if there was 100% today, how much would be left in 9 days?
An atom with different number of neutrons
The half life is 3 days
9 days is 3 half lifes so....
Half lives 0 1 2 3
% 100 50 25 12.5%
What are the key structures in the national grid to get power from the power plant to the home?
Turbine at the power plant - step up transformer - step down transformer - circuit breaker panel at the home
You are designing the lighting in your home. Do you choose to wire the whole house in series or parallel? Why?
Parallel so you can have some lights on and some off, and if one light is faulty the others still have a circuit to work
A student completed an experiment with the following equipment
1M Hydrochloric acid, 2M Hydrochloric acid, 2M Nitric acid
0.5g magneisum powder in each trial
A water bath set to 25 deg C
What is a suitable aim for this experiment?
What is the error in this experiment?
Aim - To investigate the effect of acid strength on the reaction with magnesium powder
Error - they changed their acid strength and their acid name
What factors affect resistance in a circuit?
Why do electrical engineers take this into consideration?
Length of the wire
The material of the conductor
The diameter of the conductor
Engineers need to know these so they can calculator current for fuses/protection and heat.