science Flashcards
What do state symbols tell us
liquid=(l)
solid=(s)
gas=(g)
aqueous solution=(aq)
all lower case
what are the effects of acid rain
acid rain affects living organisms as well as materials
What is the difference between a chemical and physical change
physical change= no new chemicals formed
reversible
etc. melting = solid-liquid
chemical change = new substances formed
not reversible
etc. reactants-products
What is the reactivity series of metals
- potassium most
sodium - calcium
magnesium
3.aluminisium
4.(carbon)
Z zinc
I iron
T tin
L lead
hydrogen
jewellery
copper
silver
gold
expensive platinum
What is the difference between an acid and a base
acids tend to taste sour
bases tend to taste bitter
litmus paper turns red in acids
litmus paper turns blue in bases
acids contain hydrogen
What happens in a displacement reaction
occurs when a more reactive metal takes place of a less reactive metal
e.g.
potassium+copper nitrate —- potassium nitrate + copper
in the Ph scale what does it mean if it is a reddish colour
strong acid
in the Ph scale what does it mean if the colour is yellow/green
weak acid
in the Ph scale what does it mean if the colour is green/blue
weak base
in the Ph scale what does it mean if the colour is blue/purple
strong base
what numbers are acidic in the Ph scale
1,2,3,4,5,6
What number is neutral in the Ph scale
7
What numbers are alkaline in the Ph scale
8,9,10,11,12,13,14
What happens when acid reacts with metals
see bubbles as hydrogen is made
temperature increases because it is exothermic reaction
more reactive the metal the bigger the increase
What happens in an exothermic reaction
energy is given out to the surroundings
temperature increases
e.g. copper sulfate + water
What happens in an endothermic reaction
energy is taken in from the surroundings
temperature decreases
e.g. sodium hydrogen carbonate + acid
What happens in a neutralisation reaction
is a reaction between an acid and an alkali
the end point of a reaction is a neutral substance
how do catalysts affect chemical reactions
catalyst: chemical that speeds up reactions so they can be used again and again and again
What is the circuit symbol for a bulb
circle with x in it
How do you calculate resistance
resistance= potential difference divided by current
What is an electromagnet
current carrying wire coil wrapped around an iron bar
What are the ends of a magnet called
poles
What are the three magnetic elements
iron (Fe)
Cobalt (Co)
Nickel (Ni)
Where is the magnetic force strongest
poles of a magnet
What happens when two opposite charges are brought together
attract
What charge do electrons have
negative
What is the name of the force that acts between charged objects
electrostatic
Is the force that acts between charged object a contact or non-contact force
non contact
What is an independent variable
the thing we change
What is a dependent variable
the thing we measure
What is a control variable
the thing we keep the same
How can we change the strength of the magnetic force of an electromagnet
changing the size of the current
changing the number of turns of wire
What is the unit of resistance called
ohms
What is current
the flow of charge
What is a resistor
a component we add to a circuit to add resistance
