Particle Model of Matter

Question 1

RP5. use appropriate apparatus to make and record the measurements needed to determine the densities of regular and irregular solid objects and liquids.

Answer 1

1. Density of a regular object: measure with a ruler l,w,h (with a sphere use vernier callipers and (4/3pi*r^3), measure mass with a top pan balance, use the equation mass/volume=density.
2. Density of an irregular object: mass, fill a displacement can to the top and allow to empty to just below the pipe, set up a measuring cylinder to catch water below pipe, lower object into can, measure volume of displaced water, calculate density.
3. Density of a liquid: mass of empty measuring cyclinder, mass with 50cm^3 of liquid in cylinder, subtract masses, calculate density.

Systematic error: zero error of balances.
Random error: different cylinder resolutions, parallax error, water spilled out by accident from eureka can.

Hazards: water spilled from displacement can.
Risks: slip and fall.
Precautions: use a measuring cylinder to collect water.

Question 2

What are the specific names for changes of state?

Answer 2

Specific latent heat of fusion (s to l) and vaporisation (l to g).