1 What are the three states of matter?
solid, liquid, gas
2 In which state are the particles arranged regularly?
3 In which state do particles move quickly in all directions?
4 What state change happens when a substance melts?
solid to liquid
5 What state change happens when a substance condenses?
gas to liquid
6 In general, which state of matter has particles with the highest energy?
7 What is the melting point of water in °C?
8 What is the boiling point of water in °C?
9 When a substance is melted, is energy transferred to or from the surroundings?
from (The substance gains energy from the surroundsing)
10 The melting point of sodium is 97.7 °C. What is the state of sodium at 25.0 °C?
solid (The temperature is below the melting point, so it hasnt yet melted!)
11 Gold is a pure substance. T or F?
true (although you can get alloys of gold which are mixtures and not pure substances)
12 Air is a mixture. T or F?
true (it is mixture mostly of the elements Nitrogen (N2) and Oxygen (O2))
13 Carbon dioxide is a mixture. T or F?
false (it is a compound of carbon and oxygen)
14 Pure substances only have one type of atom present T or F?
false (you can get pure compounds e.g. you can get pure salt, NaCl)
15 All mixtures are made up of compounds. T or F?
false (you can get a mixture of elements, for example air)
16 Pure substances have a sharp melting temperature. T or F?
true (as opposed to mixtures which melt over a temperature range)
17 A metal alloy is likely to melt over a range of temperatures. T or F?
true (because it is a mixture)
18 The temperature changes as a pure substance melts. T or F?
false (the temperatue stays constant as the energy is used to change state (break bonds))
19 When a substance melts, its particles move around and become less ordered. T or F?
20 A heating curve with an upward sloping gradient during melting indicates a pure substance is present. T or F?
false (for a pure substance the heating curve is flat during a state change)
21 What is a mixture?
different elements and/or compounds that are not chemically joined together
22 Which is a mixture, air or water or both?
air (as long as the water is pure water)
23 Which of a ‘mixture’ or a ‘pure substance’ has a fixed composition?
24 Name a pure substance.
any suitable e.g. gold, salt, water can all be pure
25 Why can’t a pure substance be separated into other substances using physical means?
it has the same fixed composition in all of its parts
26 Is melting a physical process or a chemical process?
27 Is a material that melts over a range of temperatures likely to be a mixture or a pure substance?
28 Give one safety precaution to take when heating substances.
any suitable, tie hair back, tuck tie in, wear safety specs
29 What do we call the change of state from a liquid to a gas?
30 Name a mixture that could be separated by filtration?
any suitable e.g. sand and water