P6- Molecules and matter

Question 1

What is density

Answer 1

The mass per volume of a substance

Question 2

3 ways to find the volume of an object

Answer 2

Regular object- Use measurements to calculate volume, calculate mass using a balance
Irregular object- Tie string to it, place in half full measuring cylinder, calculate water level rise
Irregular object- Fill eureka can w water up to spout, place object in, collect water from spout in beaker. Measure displaced water with measuring cylinder

Question 3

When do objects float on water?

Answer 3

If they have a lower density than water

Question 4

Physical change?
Example?

Answer 4

No new substances are produced
Changing state

Question 5

Conservation of mass meaning in states of matter

Answer 5

When a substance changes state the mass stays the same

Question 6

Particles in solid
Arrangement?
Energy?

Answer 6

Next to each other in fixed positions
Least energetic

Question 7

Particles in liquid
Arrangement?
Energy?

Answer 7

Move around at random, touch each other
More energetic

Question 8

Particles in gas
Arrangement?
Energy?
Density?

Answer 8

Move randomly and far apart
Most energetic
Much less dense than solids and liquids

Question 9

The temperature of water when heated over time

Answer 9

-Increases until 0°, ice starts to melt
-Stays at 0° until all ice has melted
-Increases from 0° to 100°, water starts to boil
-Stays at 100° until all water turns to steam

Question 10

Specific latent heat

Answer 10

The energy transferred to a substance when it changes state

Question 11

Where does boiling and evaporation occur in a liquid and when?

Answer 11

Boiling- throughout a liquid at its boiling point
Evaporation- surface of liquid when below boiling point

Question 12

How to tell the melting and boiling point of a substance from a temp-time graph?

Answer 12

The flat section

Question 13

Internal energy definition and sum

Answer 13

Kinetic energy + potential energy
The energy of particles caused by their motion and position

Question 14

Kinetic energy increases by…
Potential energy increases by…

Answer 14

Rise in temperature

Change of state

Question 15

What determines the state of matter? (particles)

Answer 15

The strength of the forces of attraction between particles

Question 16

Pressure

Answer 16

The force of the particles colliding with the sides of a container

Question 17

What happens to gas pressure if temp increases?

Answer 17

-Gas particles move quickly in random directions
-Pressure is collision of particles with sides of container
-Particles gain KE, move quicker, collide w sides of container more frequently w more force
-Pressure increases

Question 18

How can the random movement of gas molecules be shown?

Answer 18

By smoke as it moves in a similar unpredictable motion

Question 19

Latent heat

Answer 19

Energy needed for a substance to change state without changing temp

Question 20

Latent heat of fusion

Answer 20

The energy needed to change the 1kg of a substance from solid to liquid (melting)

Question 21

Latent heat of vaporisation

Answer 21

The energy need to change 1kg of a substance from liquid to gas (vaporisation)

Question 22

Boyle’s law

Answer 22

At a constant temp:
-if volume doubles, pressure halves
-if volume halves, pressure doubles

Question 23

What happens to gas pressure if volume decreases?

Answer 23

-Particles forced closer together
-More collisions with sides of container
-Increases pressure

Question 24

What happens to gas if it is compressed rapidly and why?

Answer 24

Temp of gas can increase, work is done, energy not transferred to surroundings quick enough

Question 25

What happens to gas if it is compressed slowly and why?

Answer 25

Work is done, energy is transferred to surroundings at same rate as energy to gas. Temp of gas doesn’t change