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
31 What is a pure substance?
any from: cannot be separated by physical means; same composition throughout; same properties throughout; constant chemical composition
32 What is the difference between a mixture and a compound?
in a compound, different elements are joined chemically
33 Is salty water a mixture or a compound?
mixture; strictly, a mixture of two compounds, water and salt
34 How can you separate sand mixed with salty water?
35 Why can’t you use filtration to get the salt from salty water?
salt has dissolved; pieces are too small
36 How can you get salt from salty water?
evaporate the water; crystallisation
37 What is the scientific name for a mixture like salty water?
38 What is the term used for the liquid in a solution?
39 What is the term for the substance that has dissolved in the solution?
40 How can you identify a pure substance on a chromatogram?
only one spot/colour
41 What are the three states of matter?
solid, liquid, gas
42 What word describes a solid that dissolves in a liquid?
solute or soluble
43 What name is given to a liquid that will dissolve a particular solid?
44 What is the boiling point of water?
45 How can we separate an insoluble solid from a liquid?
46 What word describes the clear liquid that comes through the filter paper?
47 Is mineral water pure or impure?
impure (it contains dissolved salts)
48 What process takes place when a liquid turns into a gas?
49 What process takes place when a gas turns into a liquid?
50 What process takes place when a liquid is changing from a liquid to a gas throughout its volume (not just at its surface)?
boiling (evaporation is the surface process)
51 Which of these, if any, is pure water? Mineral water, tap water, seawater.
none of them (distilled water is pure water all of these contian dissolved salts (ions))
52 Give an everyday use of tap water.
53 Which of these is soluble in water – sand or salt?
54 What separation method is used to remove insoluble solids from a liquid?
55 What is the boiling point of water in degrees Celsius?
56 What separation method could you use to separate water from ink?
57 Name the two state changes involved in distillation.
boiling/evaporating and condensing
58 Why does sand sink to the bottom of a bucket of water?
it is denser than water/does not dissolve
59 What gas with a sharp smell is used to kill bacteria in swimming pool water?
60 Why does seawater taste salty?
it contains dissolved salt