Properties and Structure of matter Flashcards
What is absolute uncertainty?
Absolute Uncertainty is when a measurement does not have an exact value and thus can have uncertain amounts of decimals occurring within it.
For example, when we measure something, it may not be 100% precise, which is why we include absolute uncertainty after a number. The symbol for absolute uncertainty is ± (plus minus)
Absolute Uncertainty is ALWAYS ±1/2 of the smallest ‘division’ or ‘unit’ ONLY FOR ANALOG DEVICES
What are the two types of conventions when dealing with absolute uncertainty? How do you find absolute uncertainty?
The two types of conventions include ANALOG and DIGITAL equipment.
Absolute Uncertainty in ANALOG devices is found by halving the smallest division based on the gap. For example, if an analog device such as a beaker has a scale going up by 5, then the absolute uncertainty would be ±2.5. Thus, if the liquid within the beaker measured 10 millilitres, then the proper answer would be 10 ML ± 2.5
Absolute Uncertainty in DIGITAL DEVICES is found by ONLY FINDING THE SMALLEST DIVISION. For example, if a digital weight showed that an apple weighed 84.02 grams, the SMALLEST DIVISION would be 0.01. Therefore, the absolute uncertainty would simply be ±0.01. Hence the answer is 84.02±0.01 grams
What is relative uncertainty? How do you calculate it?
How is it different from percentage uncertainty?
Relative Uncertainty is found out by:
Absolute Uncertainty/ Measured Value
E.g. The analog device with a scale of 1 (going up by 1) shows that an ice cube measures 5 mm.
Absolute Uncertainty = ±1/2 of smallest division (ANALOG)
Therefore, Absolute Uncertainty = ±0.05
Measured Value = 5mm
Therefore, relative uncertainty = 0.05 / 5 = 0.01
RELATIVE UNCERTAINTY DOES NOT HAVE ANY UNITS OF MEASUREMENT
(RELATIVE UNCERTAINTY AND PERCENTAGE UNCERTAINTY ARE DIFFERENT)
PERCENTAGE UNCERTAINTY WOULD EXPRESS THE RELATIVE UNCERTAINTY AS A PERCENTAGE AND WOULD THUS BE:
RELATIVE UNCERTAINTY X 100%
What is particle theory?
Particle theory states that all matter is made up of extremely tiny particles and each pure substance has its own kind of particle, different from the particles from other pure substances.
What are the three fundamental states of matter?
Solids, Liquids and Gases
Is temperature and kinetic energy directly related?
Yes; the greater the temperature of a substance, the more kinetic energy the particles of that substance contain
What is the order of the states of matter in terms of the greatest amount of kinetic energy to the least?
Gases, Liquids and lastly Solids
What are molecules?
Molecules are chemical structures, made up of two or more atoms held in a fixed arrangement, by chemical bonds. Molecules can consist of more than one type of atom.
What are the two main types of matter? Give an example for both.
Pure substances and Mixtures.
Pure substance examples - elements or compounds
Mixture examples - Heterogeneous and Homogeneous
What are the definitions of pure substances and mixtures? Hence, what is the difference between the two?
Pure substances are made up of one type of particle and have a fixed chemical composition throughout. Pure substances have defined chemical and physical properties.
Mixtures are substances that are made up of more than one type of particle. Mixtures only have PHYSICAL properties.
Mixtures are made up of two or more substances that are not chemically bonded together.
Therefore, the difference is that pure substances can be separated chemically whereas mixtures cannot. Mixtures can only be separated physically. Mixtures were never chemically bonded together.
What are the different types of mixtures? Define and give examples.
Heterogeneous and Homogeneous
Heterogeneous mixtures are when the composition varies within the mixture and it is not uniform. Examples include soil or oil and water, where there is a clear distinction of uneven spread.
Homogeneous mixtures have a uniform composition, meaning that any sample of the mixture will be just as identical as any other sample taken. Examples include salt dissolved in water or even vodka. (Even composition of alcohol)
What is the difference between compounds and homogeneous mixtures?
Homogeneous mixtures can only be separated physically while compounds have chemical bonds, meaning they are separated through chemical means.
What are examples of physical properties?
Malleability (Ability to be hammered into thin sheets)
Ductility (Ability to be stretched into wires)
Brittleness (Tendency to shatter when placed under pressure)
Melting Point
Boiling Point
Density
Electrical Conductivity
Examples of Chemical Properties?
Reactivity
Electronegativity (Tendency to gain electrons)
Flammability
Corrosiveness (Ability to cause the metal to rust)
Ionisation Energy (Energy needed to remove an electron from a gaseous state)
Effervescence
Color change
What are the 6 main methods of separation in Heterogeneous Mixtures?
Decanting - (the process of pouring away a liquid while leaving a solid (often a precipitate) behind.)
Sieving (separating solid from solid)
Filtration (Separating solid from liquid)
Separating Funnel
Centrifugation
Magnetic Separation
