Answers to Chemistry Homework
5.1 From Particles to Solutions p. 178 # 8,9,10
Pane of glass – solution
Chocolate chip ice cream – mechanical mixture
Clear apple juice – solution
Pizza – mechanical mixture
Garbage in garbage can – mech. Mixture
You need an alloy that heats up and liquefies quickly but also
solidifies(sets) quickly.
Lead is toxic to humans. It can cause cancer. We are trying to remove it
from many items.
5.2 Physical Properties p. 182 # 1, 2, 3, 4 a-d
Qualitative property describes the quality. It is a descriptive observation that uses the 5 sense.
ie: it was red. A quantitative property describes the quantity – the number. These are measured
observations so they always include a number ie: length is 5 cm.
a) colour is qualitative property
b) 60 cm - quantitative property
c) qualitative
d) quantitative (#)
Mountain bikes –
• strong – should be able to go over bumps and not break
• light weight – you need to power it so heavier is harder. Also you may need to lift it once in a
while
• anything else?
Remember: colour and state are always 2 properties you can list fairly easily
a) Copper wire – ductile (make into wire), flexible (wires aren’t always straight), metallic lustry
(shiny), thin (wires are not usually very thick
b) 500 g of butter – yellow, solid, soft, smooth
c) glass of milk – liquid state, low viscosity, opaque (can’t see through), has little or no smell,
white
d) candle – flammable (it burns), solid, soft (can easily scratch it), dull (most often it is not shiny)
5.3 Chemical Properties p. 186 # 1-7
A physical change does not change the substance. If I cut up paper, it is smaller but it is still
paper. That is a physical change. A chemical change indicates that the substance has changed. If
I burn paper, it is no longer paper. It has become ash or soot. That is a chemical change.
Water freezing is not a chemical change – it did not stop being water. It just went from being
liquid water to solid water. Water freezing is a physical change.
• Metallic lustre – physical property – it describes how metal looks. It is still metal.
• Boiling point – physical property – it describes the temperature at which the substance
changes state from liquid to gas. All state changes are physical properties.
• Explodes when ignited – chemical property – when something it explodes, it changes. It is no
longer the same substance. Explosion is not a state change.
• changes colour when mixed with water – I don’t like this clue – ask me why in class.
• water boiling – physical change – water has just changed state – it is still water
• wood is sawed / made into box – physical change – it is still wood but a different shape.