State changes(+phys and chem changes)

Question 1

What are the particles like in a liquid compared to a solid

Answer 1

In a liquid the particles are close together and move around each other with frequent collisions

however

in a solid the particles are also close together but regularly arranged and vibrating

Question 2

Why can a liquid and solid not be compressed but a gas can?

Answer 2

Liquids and solids cannot be compressed because their particles are packed closely together

but gases can be compressed because their particles are far apart with lots of space between them.

Question 3

What is happening on a steep line on a heating/cooling graph?

Answer 3

-Temperature changes
( line upwards is rising temp downwards is falling temp)

-substances do not change state

Question 4

What is happening on a flat line on a heating/cooling graph?

Answer 4

-Temperature stays constant
-state change occurs

Question 5

Are the bonds BREAKING or FORMING in the following?

1. melting
   2.condensing
2. freezing
   4.boiling

Answer 5

1. melting - B
   2.condensing- F
2. freezing - F
   4.boiling - B

Question 6

Why does the temperature remain CONSTANT during a change of state?

Answer 6

because the average kinetic energy of particles does NOT change ( and instead energy goes into breaking and forming intermolecular forces
)

extra:
during a change of state, the kinetic energy of the particles stays the same. The energy goes into breaking or forming intermolecular forces, not making the particles move faster.

Question 7

During melting and boiling (gap fill)

………. increases and particles gain (……) energy

-so move about more/less

-particles have enough energy to …. the forces of …. that held them……
( therefore causing a change of state)

Answer 7

ENERGY increases and particles gain (KINETIC) energy

-so move about MORE

-particles have enough energy to OVERCOME the forces of ATTRACTION that held them TOGETHER ( therefore causing a change of state)

Question 8

NOW WITH NO GAP FILL:

What happens to the energy during BOILING and MELTING

Answer 8

ENERGY increases and particles gain (KINETIC) energy

-so move about MORE

-particles have enough energy to OVERCOME the forces of ATTRACTION that held them TOGETHER
( therefore causing a change of state)

Question 9

What changes during a state change?

Answer 9

the BONDING ENERGY between particles change

?

Question 10

Give 5 signs of a chemical change

Answer 10

-colour change
-temperature change
-gas production
-precipitation (solid forms from a solution)

-change in characteristic properties
(odour, light given off)

Question 11

DEFINE:

physical change

Answer 11

is a change in a substance that doesn’t produce a new substance/product

Question 12

DEFINE:
chemical change

Answer 12

a change that produces a new product with different chemical properties

Question 13

Give 1 difference between a physical and chemical change

Answer 13

physical change can usually be reversed

however

a chemical change cannot be reversed easily