P1.2 Density

Question 1

What is density?

Answer 1

A measure of compactness, relating the mass of a substance to how much space it takes up.

Question 2

How to work out density?

Answer 2

D = mass / volume

Question 3

What are the units of density?

Answer 3

Kg/m^3

Question 4

Which state of matter is most dense, and why?

Answer 4

Solid, there are more particles in 1cm of a substance than in gas state leading to a higher overall mass, meaning the solid is denser.

Question 5

What does density depend on?

Answer 5

Particle arrangement and mass of particles

Question 6

What experiment can be used to calculate the density of an irregular object?

Answer 6

1. Weigh the mass of the object
   2. Fill up eureka can with water til just under the spout.
   
   3. Place measuring cylinder under spout and gently lower object into can.
   4. Displaced water will come out of spout, wait til it stops dripping.
   5. Measure volume of water collected in cylinder (this is volume of object)
   6. Repeat 3 times and calculate mean of results for accuracy
      
      7. Divide the mass by the volume to calculate the density.

Question 7

How to find the volume of an object?

Answer 7

An object submerged in water will displace a volume of water equal to its own volume.

Question 8

Law of conservation of mass?

Answer 8

You have to add or remove material for the mass of a system to change, particles don’t appear or disappear.

Question 9

Density of water?

Answer 9

1g/cm^3

Question 10

Calculate density of block of material with mass 160g and volume 200cm^3 (2 marks)

Answer 10

160g = 0.16 kg
0.16/200 = 0.0008 kg/m^3

Question 11

Object has mass of 4.5 x 10^-2 kg and a volume of 75 cm^3. Calculate its density

Question 12

Closed system?

Answer 12

No particles can escape or enter

Question 13

How does a closed system affect mass and volume?

Answer 13

Mass of substance isnt affected when changing state (physical change)

Change of state means change in volume, therefore density is also affected.