Topic 5 -Particles

Question 1

What is density ?

Answer 1

Density tells us the mass for a given colme
Density (kg/mcubed) =Mass(kg)/Volume(m3
m/d*v

Question 2

What are regular and irregular objects ?

Answer 2

Regular objects have diemsnions that are easy to measure .
Irregular objects cannot easily measure thier dimensions .

Question 3

How to work out denisty of regular objects ?

Answer 3

-Determine mass using a balnce .
Volume - measure legnth of side and cube it as volume is lwh
density = mass dividied by volume

Question 4

How to work out density in irregular objects ?

Answer 4

-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 .

Question 5

Characteristics of a solid .

Answer 5

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 .

Question 6

Charcateristics of a liquid?

Answer 6

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 .

Question 7

Characteristics of a gas ?

Answer 7

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 .

Question 8

Change the state of substance …

Answer 8

by putting in or taking out energy .

Question 9

Changing a solid to a liquid ?

Answer 9

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 .

Question 10

Stronger froce ofatreaction …

Answer 10

more enegry needed ot be put in to break ofrces . Higher melting point . ax low melting point as forces of atraction between bonds weak .

Question 11

changing liquid to to solid

Answer 11

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 .

Question 12

Gas to a liquid

Answer 12

CONDENSING , TAKES PALCE A BOILIGN POINT .

Question 13

Problem with particle model ?

Answer 13

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 .

Question 14

All particles have …

Answer 14

Kinetic energy
-particles also have potentioan energy (ointremolecular and chemical bonds .)

Question 15

What is internal energy ?

Answer 15

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 .

Question 16

Internal energy heating a solid .

Answer 16

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 .

Question 17

Intenral energy cooling down a agas ?

Answer 17

-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 )

Question 18

What is asolid turning directy into a gas

Answer 18

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 .

Question 19

What is evaporaiton ?

Answer 19

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 .

Question 20

first stage of heating curve

Answer 20

temp of solid rising as we icnrese energy of rparitcle s.
EMP STOPS RISING AND LINE BECOMES HORIZIONTAL . SOLID CHANGING STATE TURNIGN INTO LIQUID .

Question 21

Change of state on ehating curve /

Answer 21

-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 .

Question 22

What doe a fuse do

Answer 22

-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 .