Structure of matter and the size of molecules
Answers are for parents and teachers.
1
Find the relative molecular mass of methanol CH₃OH (C = 12, H = 1, O = 16).
32
2
An oil molecule is about 2·10⁻⁹ m across. If an oil drop of volume 0.3 mm³ spreads over water into a layer one molecule thick, what area does the film cover?
S = V/d = 0.3·10⁻⁹ m³ / 2·10⁻⁹ m = 0.15 m²
3
Give your own everyday example supporting one of the three MKT statements and explain it.
For example, washing powder dissolves and spreads in water, showing random particle motion (diffusion).
4
Why do smoke particles in air keep jerking instead of staying still? Explain briefly.
Air molecules hit them randomly and the net force keeps changing.
5
A water molecule has a mass of about 3·10⁻²⁶ kg. With 1 u ≈ 1.66·10⁻²⁷ kg, what M_r results (rounded)?
about 18