Download 30 - Edgemead High School

GRADE 11 PHYSICAL SCIENCES
OUTLINE JUNE EXAMINATION 2016
FORMAT
Physics and Chemistry Focus
3 hours
Multiple-choice questions
Marks
20
Longer questions assessing all themes
130
Total
COGNITIVE LEVELS
Recall
Comprehension
Analysis, Application
Evaluation, Synthesis
150
15 %
30 %
45 %
10 %
CONTENT
VECTORS IN TWO DIMENSIONS
Resultant of perpendicular vectors,
 Draw a sketch of the vectors (parallel and perpendicular) on the Cartesian
plane
 Add co-linear vectors along the parallel and perpendicular direction to obtain
the net parallel component (Rx) and a net perpendicular component (Ry)
 Sketch Rx and Ry and determine the magnitude of the resultant using the
theorem of Pythagoras.
 Determine the resultant vector using a calculation (by component method) for
a maximum of four force vectors in both 1-Dimension and 2-Dimensions
 Understand what is a closed vector diagram
 Determine the direction of the resultant using simple trigonometric ratios
Resolution of a vector into its parallel and perpendicular components
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Draw a sketch of the vector on the Cartesian plane showing its magnitude and
the angle (θ) between the vector and the x-axis
Use Rx= Rcos(θ) for the resultant x-component
Use Ry= Rsin(θ) for the resultant y-component
NEWTON'S LAWS AND APPLICATION OF NEWTON'S LAWS
Different kinds of forces: weight, normal force, frictional force, applied force
(push, pull), tension (strings or cables)
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Define normal force, N, as the force or the component of a force which a
surface exerts on an object with which it is in contact, and which is
perpendicular to the surface.
Define frictional force, f, as the force that opposes the motion of an object
and which acts parallel to the surface.
Define static frictional force, fmaxs, as the force that opposes the tendency of
motion of a stationary object relative to a surface.
Define kinetic frictional force, fk, as the force that opposes the motion of a
moving object relative to a surface.
Know that a frictional force:
 Is proportional to the normal force
 Is independent of the area of contact
 Is independent of the velocity of motion
Solve problems using fsmax = μsN where fsmax is the maximum static frictional
force and μs is the coefficient of static friction.
NOTE:
 If a force, F, applied to a body parallel to the surface does not cause the
object to move, F is equal in magnitude to the static frictional force.
 The static frictional force is a maximum (fsmax) just before the object starts to
move across the surface.
 If the applied force exceeds fsmax, a resultant/net force accelerates the object.
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Solve problems using fk = μkN, where fk is the kinetic frictional force and μk the
coefficient of kinetic friction.
Force diagrams, free-body diagrams
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Draw force diagrams.
Draw free-body diagrams. (This is a diagram that shows the relative
magnitudes and directions of forces acting on a body/particle that has been
isolated from its surroundings)
Resolve a two-dimensional force (such as the weight of an object on an
inclined plane) into its parallel (x) and perpendicular (y) components.
Determine the resultant/net force of two or more forces.
Newton's first, second and third laws of motion
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State Newton's first law of motion: A body will remain in its state of rest or
motion at constant velocity unless a non-zero resultant/net force acts on it.
Discuss why it is important to wear seatbelts using Newton's first law of
motion.
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State Newton's second law of motion: When a resultant/net force acts on
an object, the object will accelerate in the direction of the force at an
acceleration directly proportional to the force and inversely proportional to the
mass of the object.
Draw force diagrams and free-body diagrams for objects that are in
equilibrium or accelerating.
Apply Newton's laws of motion to a variety of equilibrium and non-equilibrium
problems including:
A single object:
- Moving on a horizontal plane with or without friction
- Moving on an inclined plane with or without friction
- Moving in the vertical plane (lifts, rockets, etc.)
Two-body systems (joined by a light inextensible string):
- Both on a flat horizontal plane with or without friction
- One on a horizontal plane with or without friction, and a second hanging
vertically from a string over a frictionless pulley
- Both on an inclined plane with or without friction
- Both hanging vertically from a string over a frictionless pulley
State Newton's third law of motion: When one body exerts a force on a
second body, the second body simultaneously exerts a force of equal
magnitude in the opposite direction on the first body.
Identify action-reaction pairs.
List the properties of action-reaction pairs.
Newton's Law of Universal Gravitation
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State Newton's Law of Universal Gravitation: Each body in the universe
attracts every other body with a force that is directly proportional to the
product of their masses and inversely proportional to the square of the
distance between their centres.
Gm1m2
Solve problems using . F=
r2
Gm
Calculate acceleration due to gravity on a planet using . g = 2
r
Describe weight as the gravitational force the Earth exerts on any object on or
near its surface.
Calculate weight using the expression w = mg.
Calculate the weight of an object on other planets with different values of
gravitational
Distinguish between mass and weight.
Explain weightlessness.
ATOMIC COMBINATIONS: MOLECULAR STRUCTURE
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Represent atoms using Lewis diagrams
Explain, referring to diagrams showing electrostatic forces between protons
and electrons, and in terms of energy considerations, why - two H atoms form
an H2 molecule, but He does not form He2
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Draw a Lewis diagram for the hydrogen molecule
Describe a covalent chemical bond as a shared pair of electrons
Describe and apply simple rules to deduce bond formation, viz.
o different atoms, each with an unpaired valence electron can share
these electrons to form a chemical bond
o different atoms with paired valence electrons called lone pairs of
electrons, cannot share these four electrons and cannot form a
chemical bond
o different atoms, with unpaired valence electrons can share these
electrons and form a chemical bond for each electron pair shared
(multiple bond formation)
o atoms with an incomplete complement of electrons in their valence
shell can share a lone pair of electrons from another atom to form a coordinate covalent or dative covalent bond (e.g. NH4+, H3O+)
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Draw Lewis diagrams, given the formula and using electron configurations, for
o simple molecules (e.g. F2, H2O, NH3, HF, OF2, HOCℓ)
o molecules with multiple bonds e.g. (N2, O2 and HCN)
Molecular shape as predicted using the Valence Shell Electron Pair Repulsion
(VSEPR) theory
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State the major principles used in the VSEPR
The five ideal molecular shapes according to the VSEPR model. (Ideal
shapes are found when there are NO lone pairs on the central atom ONLY
bond pairs.) A is always the central atom and X are the terminal atoms
o linear shape AX2 (e.g. CO2 and BeCℓ2)
o trigonal planar shape AX3 (e.g. BF3)
o tetrahedral shape AX4 (e.g. CH4)
o trigonal bipyramidal shape AX5 (e.g. PCℓ5)
o octahedral shape AX6 (e.g. SF6) Molecules with lone pairs on the
central atom CANNOT have one of the ideal shapes e.g. water
molecule
o Deduce the shape of
molecules like CH4,NH3, H2O, BeF2 and BF3
molecules with more than four bonds like PCℓ5 and SF6, and
molecules with multiple bonds like CO2 and SO2 and C2H2 from their
Lewis diagrams using VSEPR theory
Electronegativity of atoms to explain the polarity of bonds.
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Explain the concepts
- Electronegativity
- Non-polar bond with examples, e.g. H-H
- Polar bond with examples e.g. H‑ Cℓ
Show polarity of bonds using partial charges δ+ H - Cl δCompare the polarity of chemical bonds using a table of electronegativities
With an electronegativity difference ΔEN > 2.1 electron transfer will take
place and the bond would be ionic
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With an electronegativity difference ΔEN > 1 the bond will be covalent and
polar
With an electronegativity difference ΔEN < 1 the bond will be covalent and
very weakly polar
With an electronegativity difference ΔEN = 0 the bond will be covalent and
non-polar
Show how polar bonds do not always lead to polar molecule
Bond energy and length
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Define bond energy
Define bond length
Explain the relationship between bond energy and bond length
Explain the relationship between the strength of a bond between two
chemically bonded atoms and the
length of the bond between them
size of the bonded atoms
number of bonds (single, double, triple) between the atoms
Intermolecular forces
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Name and explain the different intermolecular forces: (i) ion-dipole forces, (ii)
ion-induced dipole forces and (iii) dipole-dipole forces (iv) dipole-induced
dipole forces (v) induced dipole forces with hydrogen bonds a special case of
dipole-dipole forces. The last three forces (involving dipoles) are also called
Van der Waals forces
Explain hydrogen bonds (dipole-dipole)
Define a covalent molecule
Distinguish between intermolecular forces and interatomic forces using a
diagram of a group of small molecules; and in words
Represent a common substance, made of small molecules, like water, using
diagrams of the molecules, to show microscopic representations of ice
H2O(s), water liquid H2O(ℓ) and water vapour H2O(g)
Illustrate the proposition that intermolecular forces increase with increasing
molecular size with examples e.g. He, O2, C8H18 (petrol), C23H48(wax). (Only
for van der Waals forces.)
Explain density of material in terms of the number of molecules in a unit
volume, e.g. compare gases, liquids and solids
Explain the relationship between the strength of intermolecular forces and
melting points and boiling points of substances composed of small molecules
Contrast the melting points of substances composed of small molecules with
those of large molecules where bonds must be broken for substances to melt
Describe thermal expansion of a substance and how it is related to the motion
of molecules in a substance composed of small molecules e.g. alcohol in a
thermometer
Explain the differences between thermal conductivity in non-metals and
metals
GEOMETRIC OPTICS
Refraction
 State the law of reflection
 Define the speed of light as being constant when passing through a given
medium and having a maximum value of c =3 x 108 m.s-1 in a vacuum.
 Define refraction
 Define refractive index as n = c/v
 Define optical density
 Know that the refracted index is related to the optical density.
 Explain that refraction is a change of wave speed in different media, while the
frequency remains constant
 Define Normal
 Define angle of incidence
 Define angle of refraction
 Sketch ray diagrams to show the path of a light ray through different media
Snell’s Law
 State the relationship between the angles of incidence and refraction and the
refractive indices of the media when light passes from one medium into
another (Snell’s Law) n1sin θ1 = n2sinθ2
 Apply Snell’s Law to problems involving light rays passing from one medium
into another
 Draw ray diagrams showing the path of light when it travels from a medium
with higher refractive index to one of lower refractive index and vice versa
Critical angles and total internal reflection
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Explain the concept of critical angle
List the conditions required for total internal reflection
Use Snell’s Law to calculate the critical angle at the surface between a given
pair of media
Explain the use of optical fibres in endoscopes and telecommunications
QUANTITATIVE ASPECTS OF CHEMICAL CHANGE
The mole concept
 Define one mole as the amount of substance having the same number of
particles as there are atoms in 12 g carbon-12.
 Describe Avogadro’s number, NA, as the number of particles (atoms,
molecules, formula-units) present in one mole (NA = 6,023 x 1023
particles∙mol-1).
 Define molar mass as the mass of one mole of a substance measured in
g·mol-1.
 Calculate the molar mass of a substance given its formula.
Molar volume of gases
 State Avogadro’s Law i.e. one mole of any gas occupies the same volume at
the same temperature and pressure.
 At STP: 1 mole of any gas occupies 22,4 dm3 at 0 °C (273 K) and 1
atmosphere (101,3 kPa). Thus the molar gas volume, VM, at STP = 22,4
dm3∙mol-1.
Volume relationships in gaseous reactions
 Interpret balanced equations in terms of volume relationships for gases, i.e.
under the same conditions of temperature and pressure, equal amounts (in
mole) of all gases occupy the same volume.
Concentration of solutions
 Define concentration as the amount of solute per litre of solution.
n
 Calculate concentration in mol·ℓ-1 (or mol·dm-3) using c  .
V
More complex stoichiometric calculations
 Determine the empirical formula and molecular formula of compounds.
 Determine the percentage yield of a chemical reaction.
 Determine percentage purity or percentage composition, e.g. the percentage
CaCO3 in an impure sample of seashells.
 Perform stoichiometric calculations based on balanced equations that may
include limiting reagents
Motion of particles; Kinetic theory of gases
 Describe the motion of individual gas molecules:
o Molecules are in constant motion and collide with each other and the
walls of the container.
o There are forces of attraction between molecules.
o Molecules in a gas move at different speeds.
 Describe an ideal gas as a gas:
o That has identical particles of zero volume
o With no intermolecular forces between particles
o In which all collisions of the molecules with themselves or the walls of
the container, are perfectly elastic
 Explain that real gases deviate from ideal gas behaviour at high pressures
and low temperatures.
 State the conditions under which a real gas approaches ideal gas behaviour.
Ideal gas law
 State Boyle’s law: The pressure of an enclosed gas is inversely proportional
to the volume it occupies at constant temperature.
1
In symbols: p  , therefore p1V1 = p2V2, T = constant
V
 State Charles’ Law: The volume of an enclosed gas is directly proportional to
its kelvin temperature provided the pressure is kept constant.
V1 V2
, p = constant
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T1 T2
State that the pressure of a gas is directly proportional to its temperature in
p
p
kelvin at constant volume (Gay Lussac). In symbols: pT , therefore 1  2 ,
T1 T2
V = constant
For each of the above three relationships:
o Interpret a table of results or a graph
o Draw a graph from given results
o Solve problems using a relevant equation
o Use kinetic theory to explain the gas laws
pV p V
Use the general gas equation, 1 1  2 2 , to solve problems.
T1
T2
Use the ideal gas equation, pV = nRT, to solve problems.
Convert temperatures in celsius to kelvin for use in ideal and general gas
equations.
In symbols: VT , therefore
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Temperature and heating, pressure
 Explain the temperature of a gas in terms of the average kinetic energy of the
molecules of the gas.
 Explain the pressure exerted by a gas in terms of the collision of the
molecules with the walls of the container.