Topic 5 -Particles Flashcards
What is density ?
Density tells us the mass for a given colme
Density (kg/mcubed) =Mass(kg)/Volume(m3
m/d*v
What are regular and irregular objects ?
Regular objects have diemsnions that are easy to measure .
Irregular objects cannot easily measure thier dimensions .
How to work out denisty of regular objects ?
-Determine mass using a balnce .
Volume - measure legnth of side and cube it as volume is lwh
density = mass dividied by volume
How to work out density in irregular objects ?
-Find mass of a object usign a blance .
-Fill an eureka can with water .
-Now put object into warer causign water to be dispalced and flow out of the spout of eurkeka can .
-Now measure the ovlume of water that has been splacd - same as the volume of obkect .
Ten do density = mass /volume .
Characteristics of a solid .
Extremley hard to cpmres (sqeeze )
-Particles in a solid are packed together in a reufalr patter.
-lmost no spaces betwen prtciles .
Fixed shpe so can’t flow form palce to place as particlees in a solid can vibrate but cannot move from place to place .
Charcateristics of a liquid?
Liquids are hard to compress .
-Particles are close togetehr with not many spacces between them .
-Unlie soids , liquids take of thier container ans they floww from place o place as particles in lquid can move .
Characteristics of a gas ?
Extremelye asy to compress
As particles of gases re widely spaced .
Gases spread ot and fill space of heir container
Paricles in a gas move around quickly and ranodmy .
Change the state of substance …
by putting in or taking out energy .
Changing a solid to a liquid ?
Known as melting .. Moving around liquid - so more kineic energy in those particles than in a solid .
Put energy in to convert solid to a liquid - energy needed ot break the ofrce of attratcion between partciles , once force broken particles can move around .
Stronger froce ofatreaction …
more enegry needed ot be put in to break ofrces . Higher melting point . ax low melting point as forces of atraction between bonds weak .
changing liquid to to solid
freezing at its melting point
liquid to gas boilign at bilign point - strong forces of attraction betwen particles so high boilign enegry , lot of of energy eeded ot break forces in a liqudi .
Gas to a liquid
CONDENSING , TAKES PALCE A BOILIGN POINT .
Problem with particle model ?
S-Simpel particle model represebts all particles as solid speres , particles have lots of different shapes and are not solid .
-Simpe particl emdoel does not show forces betwen particle incorrect , forces between partciles have a major impact on mmelting and boiling oint of a substance .
All particles have …
Kinetic energy
-particles also have potentioan energy (ointremolecular and chemical bonds .)
What is internal energy ?
Energy stored in a system by the peaicles .
-Total kinetic energy and potential neegry of all aprticles (atoms and moelcules ) that make up a sytem .
Internal energy heating a solid .
We incres hte internal energy , at som epoint oslid turns into a liquid .
-Cotinue heting liquid , icnreas einternal energy even more at some point liquid turns into a gas .
Intenral energy cooling down a agas ?
-Reducing internal neegry , at some point turns into a liquid condensation .
-Cool liquid down furhter , reduce internal enegry and liquid turns into a soid (freezing )
What is asolid turning directy into a gas
Sublimation
co2 does this at room temperature .
-In changs of state mass is always conserved , not adding or aking aeway particles . Changes of state is a pHYSICAL not CHEMICAL chnage as if we revrse changes material recovers its original properties .
What is evaporaiton ?
Wehna liquid turns into a gas , ubt only on the surface of a liquid . As only particles on the surface have enough energy to turn into a gas .
first stage of heating curve
temp of solid rising as we icnrese energy of rparitcle s.
EMP STOPS RISING AND LINE BECOMES HORIZIONTAL . SOLID CHANGING STATE TURNIGN INTO LIQUID .
Change of state on ehating curve /
-Eneegyr we are putting in is weakeneign and breakign the forces of attraction allowing the subtance to change form a solid to liquid .
Enegeyr needed for a subsatcne to change state is LATENT HEAT ..
-Intenral energy increases howeever TEMP DOES NOT CHANGE .
repeat for boiling
for codensation
internal energy dcreases and goes on to freezing .
What doe a fuse do
-The plug contins a fuse bettwen the lvie pina nd live wire .
-If too much wire current passes htough the wire in the fuse , it emtlas and cuts the live wire off .
