definitions Flashcards

1
Q

define absolute humidity

A

the mas of water vapour present in a sample of air at a given temp. measured in kg/m3

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2
Q

define absolute zero

A

the coldest possible temperature, where nothing can be colder and where all thermal motion stops.
0 kelvins or - 273.15 degrees C

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3
Q

define an ampere

A

SI base unit of electrical current

current that produces a force of 2x 10^-7 N per meter between 2 wires of infinite length (negligible cross section) that are 1 meter apart in a vacuum.

( …. current flow through a conductor will induce an magnetic field. If two conductors are close to each other they will attract/repel each other, So the current needed to produce a certain electromagnetic force between two conductors one metre apart.)

ampere is amount of electrical charge passing a point per unit time

equivalent to 6.24x10^18 electrons (1 coloumb) per second

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4
Q

define boiling point

A

the temperature at which the vapour pressure of a liquid equals the surrounding ambient temperature and the liquid turns into a gas.

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5
Q

define calorie…

A

the amount of energy needed to rise 1g of water by 1 degree C
1 calorie = 4.16J

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6
Q

define candela …

A

the SI base unit for luminosity intensity

1 cd is the luminous intensity, in a given direction, of a source that emits
monochromatic radiation of frequency 5.4 × 10^14 hertz and that has a
radiant intensity in that direction of 1/683 watt per square radian (steradian).

A normal candle emits light with a luminous intensity of roughly 1 candela

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7
Q

define coulomb …

A

unit of charge
1 coulomb is the amount of charge passing 1 point per second when 1 amp of current is applied.
1C = 1A x 1s
equivalent to 6.24 x 10^18 electrons

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8
Q

define critical temperature…

A

the temperature above which a gas cannot be liquified by increasing pressure

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9
Q

define freezing point…

A

the temp at which the liquid and solid phases of a substance are in equilibrium at a given pressure.

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10
Q

define force…

A

A force is an influence that changes an objects state of rest or motion

1 Newton is the force required to accelerate 1kg by 1m/s^2

force has both magnitude and direction, making it a vector.

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11
Q

define gas…

A

One of the four fundamental states of matter found between the liquid
and plasma phase (four states = solid, liquid, gas and plasma)

a substance which is above its critical temperature

particles within a gas are vastly separated, space between atoms/molecules is larger than the atom/molecule itself.

a gas will expand to fill any space.

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12
Q

define heat capacity…

A

the amount of heat required to raise the temperature of an object by 1 degree C

SI unit = joule/kelvin

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13
Q

what equation relates force to accelaration?

A

F=ma

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14
Q

how is specific heat capacity turned into heat capacity?

A

specific heat capacity of an object x mass = heat capacity

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15
Q

define Hertz…

A

SI unit for frequency
1 Hertz = 1 cycle per second

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16
Q

define joule

A

1 Joule is the work done when 1 newton of force is applied over 1 meter of distance to an object
SI unit for energy

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17
Q

define kelvin

A

SI base unit for temperature
1 K is equal to 1/273.16 of the thermodynamic scale temperature of the triple point of water

The Kelvin scale is an absolute thermodynamic temperature scale, using absolute zero as its null point.

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18
Q

define kilogram

A

SI base unit for mass
The standard kilogram is the mass of a cylindrical piece of platinum iridium alloy kept in Sèvres, france

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19
Q

define kinetic energy…

A

the energy an object posses because of its motion
It is defined as the energy needed to accelerate the object from a state
of rest to its given velocity. This energy is equal to the work it would do
when decelerating to return to rest

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20
Q

define latent heat…

A

The energy released or absorbed by a substance when it changes phase
at a given temperature, e.g. ice melting

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21
Q

define specific latent heat of fusion…

A

the amount of heat required to convert a unit mass of solid at its melting point to a liquid without any increase in temperature at a given pressure.

22
Q

define specific latent heat of vapourisation…

A

the amount of heat required to convert a unit mass of liquid at its boiling point to a vapour without an increase in temperature at a given pressure

23
Q

define mass…

A

the amount of matter contained in a body.
The SI unit for this is Kg
Unlike weight, mass does not alter under conditions of differing gravity.

24
Q

define meter…

A

SI base unit for length

defined as the length of the path travelled by light in vacuum
during the time interval of 1/300 000 000th of a second.

25
Q

define mole…

A

SI base unit for amount of substance

Quantity containing the same number of particles as there are atoms
in 12 g of carbon-12. This number of particles is 6.022 × 1023 and is
known as Avogadro’s constant.

26
Q

what is the equation for momentum?

A

mass x velocity

27
Q

what is the definition of a newton?

A

SI derived unit for force
1 N is the force required to accelerate a mass of 1kg by 1m per second
squared.

28
Q

define an Ohm?

A

derived SI unit for electrical resistance

1 ohm is the resistance between two points of a conductor when a
constant potential difference of 1 volt applied between them produces a
current of 1 ampere

29
Q

define pascal…

A

derived SI unit for pressure
1Pa is the force of 1 N acting over 1m2

30
Q

define pH…

A

a measure of acidity
negative logathitm to the base 10 of H+ concentration in a solution

-log10 [H+]

31
Q

define potential energy..

A

The energy of a body or system as a result of its position in an electric,
magnetic or gravitational field. It is the potential of that body to do work.

32
Q

define power…

A

the rate of doing work.
unit = watts
1 watt = 1 joules/ sec

33
Q

define pressure

A

force per unit area
units pascal

34
Q

define relative humidity…

A

The mass of water in a given volume of air, expressed as a percentage
of the maximum mass of water that the air could hold at the given
temperature.

The ratio of the water vapour pressure to the saturated vapour pressure

35
Q

define resistance

A

Property of a conductor to oppose the flow of current through it.

The derived SI unit of electrical resistance is the Ohm (Ω)

36
Q

define saturated vapour pressure…

A

The pressure exerted by a vapour when in contact with and in equilibrium
with its liquid phase within a closed system at a given temperature.

37
Q

define a second..

A

SI base unit for time
Defined according to the frequency of radiation emitted by caesium-133
in its ground state.

One second =around 9 billion oscillations of a Caesium 133 atomic clock.

38
Q

define specific heat capacity

A

The amount of energy required to raise the temperature of 1kg of a
substance by 1°C

39
Q

what is the specific heat capacity of water and the human body?

A

> SHC of water = 4.16 kJ/kg °C
SHC of human body = 3.5 kJ/kg °C

40
Q

define the triple point of water?

A

The temperature and pressure at which water exists in equilibrium as
liquid water, solid ice and water vapour

Temperature = 0.01°C or 273.16 K, pressure = 0.006 atmosphere or
611.73 pascals

41
Q

define vapour…

A

A substance in the gas phase below its critical temperature.

42
Q

define a volt…

related to joules and coloumbs, amps and wats, amps and ohms

A

Derived SI unit of electrical potential

1volt is the potential difference between two points of a conducting wire
when 1joule of work is done to move 1coulomb of charge between them

1volt is the potential difference between two points of a conducting wire
when 1ampere dissipates 1 watt of power between them

1volt will ‘push’ a current of 1ampere through a resistance of 1 Ohm.

43
Q

define a watt…

A

SI derived unit for power
1 joule per second

44
Q

define weight…

A

The gravitational force acting on an object. Measured in newtons

Weight = mass in kg × gravitational acceleration (9.81ms–2). A mass of
1kg will therefore have 9.81 N acting on it on the surface of the earth

45
Q

what is the value for gravitational accelaration?

A

9.81m/s^2

46
Q

define work and energy

A

work done done is the energy used to push a force (N) by a certain distance (m)

as work done is the energy used, it is also measured in joules.

energy is the capacity/potential to do work. also measured in joules.

energy can be potential or kinetic - potential is to do with its position and kinetic is to do with an objects motion.

47
Q

define newtons first law

A

a body will remain either at rest or constant velocity if no net force is acting upon it.

48
Q

define newtons second law

A

F= MA

I.E. To accelerate double the mass at the same rate, double the force is required

49
Q

define newtons 3rd law

A

For every action, there is an equal and opposite reaction

If a weight applies 10N of force to the ground, the ground applies 10N of force upwards to the weight

50
Q

what is inertia?

A

the tendancy of an object to resist changes in state of motion unless a net force acts upon it.

51
Q

what does 1% solution of drug mean?

A

A 1% solution therefore is made up of 1% drug, and 99% solvent and additives

i.e. 10g/1L or 1g/100ml or 10mg/ml