問題一覧
1
define what is an element
a substance made of atoms
2
how many elements exist
113
3
an element can be converted to a simple substance
false
4
what is a compound
a combination of elements
5
which are elements in the list
Fe, o2, N2
6
the ratio of hydrogen and oxygen atoms is the same in water from tap and springs
true
7
atoms often reast so as to obtain exactly____ electrons
8
8
what are the three particles in an atom
proton, neutron, electron
9
what is a catalyser
a substance that helps a reaction but isn’t a reactant itself
10
if an atoms neucleus contains & protons, how many electrons will it have
8
11
name an element present in graphite and diamond
carbon
12
if you split the neucleus of a gold atom in 2, you will have 2 smaller gold atoms
false
13
a chemical bond is:
electron is shared between atoms
14
the chemical property of an element is mainly due to the number of electrons in its outermost orbital
false
15
the chemical properties of the elements are periodical
true
16
why does table salt conduct electricity
it is an electrolyte and when dissolved has a positive and negative electrical charge
17
what is an electrolyte
a liquid that has either a positive or negative charge
18
what is covalent bonding
2 molecules split a electron so that they have 8 in the outer orbital
19
what characteristics determine if a small particle is classified as an ion
it’s electrically charged
20
explain the formation of fossil fuels
formed from plants and animals that accumulate layers of sedements
21
fossil fuels is a renewable energy
false
22
how can we separate the different compounds of petroleum
distillation
23
gasoline is a mixture of 5 different hydrocarbons
false
24
define boiling point
the temperature at which a liquid boils and turns to vapor
25
the heavier the hydrocarbon the lower the boiling point
false
26
what are the gasses exhausted from the combustion of gasoline
carbon monoxide , carbon dioxide, unburned hydrocarbons, nitrogen and sulfur impurities
27
what is octane rating
the measure of fuel stability
28
what is a catalyst
a substance that can speed up a reaction but isn’t a reactant itself
29
what is catalytic poisinig
when metals such as iron and potassium interact with the catalyst
30
what is the solution to avoid catalytic poisoning
unleaded gasoline
31
is lead poisonous? give an example from the past
yes, in paints people would smell it and get very sick
32
how can we produce ethanol
corn
33
what is the purpose of distalation
to take the impurities out of a substance
34
in a typical petroleum refinery, the compound are separated according to
density, smell, boiling point and purity
35
straight run gasoline comes from:
directly from distillation
36
what molecule in gasoline is a cancer causing agent
benzene, ethane and butane
37
what is the main advantage of ethanol as an alternative fuel
it is produced from a biomass and burns more cleanly
38
what are the defaults of ethanol as an alternative fuel
high costs, not that much corn in the world and low energy content
39
give two exhaust gasses form the combustion of gasoline
carbon dioxide and nitrogen impurities
40
your given samples of two volatile liquids. describe how you could determine which in us the more volatile
compare their boiling points and evaporation rates
41
what is the main advantage of electricity as an alternative fuel
no exhaust, no emmison and stores battery
42
what is the main default of electricity as an alternative fuel
short driving ranges and long recharging
43
what are the main different sources for the production of electricity
hydro, wind, solar, fossil fuels
44
what is regenerative breaking
conversion of the energy of motion into electricity rather than heat
45
What would be a major advantage of using the combustion of hydrogen as a source of energy in a cars engine? What might be a major disadvantage?
advantage: better for the environment
46
what relationship exists between work and heat
heat can partially convert to work but work can fully turn to heat
47
what is the fuel used by animals to get energy
food
48
how would you define energy
one form of energy converted to another
49
what is the law of conservation of energy
energy cannot be created nor destroyed
50
what is the dominant energy in the 20th century
oil
51
how would you define potential energy
the energy in result of an objects position relative to another
52
what is the origin of heat
the motion of atoms
53
how is calorie defined
the heat needed to raise the temperature of 1 gram of water to one 1 celcius
54
in a steam engine what kinds of energies are involved
mechanical, thermal and chemical
55
what are the three products of combustion of a hydrocarbon
water, heat, carbon dioxide
56
where is stored the energy of a molecule
chemical bonds
57
In a chemical reaction when it takes more energy to break a specific bond, then to make another one how is the excess of energy released?
in the form of heat or light
58
how do you call the reaction that releases energy
exothermic
59
we can predict the energy released by a reaction
true
60
how do you define metabolism
set of chemical reactions that occur within a living organism
61
according to the energy equation energy in=energy out +_____
energy stored
62
what unit is used to quantify energy
joules
63
the human body uses energy in three different ways: give 3 ways
doing exercises, basal metabolism , dynamic action
64
what are 3 classes of chemicals we use as nutrients
carbs, fats and protein
65
what is the source of almost all our energy
hydro (97%)
66
what are the difderent sources of energy that we use
hydro, solar, wind, fossil fuels
67
why do nuclear transformations release more energy than ordinary chemical reactions
they involve changes in the neucleus
68
why is the fusion releasing so much energy
it transforms less stable nuclei into more stable
69
what are the differences between the neucleus fissions in a reactor as compared to the an atomic bomb
atomic bomb: fast and uncontrolled chain reaction and reactor is opposite
70
what equation describes the principle of equivalence between mass and energy
E= mc2
71
for any reaction that releases energy, a variation of the mass is taking place
true
72
how would you define radioactivity
atomic nuclei spontaneously decay, releasing energy in the form of radiation
73
how would you define the half life of a radioactive element
the amount of time it takes for half of the atoms to decay
74
the half life of a radio element can range from a few minutes to billions of years
true
75
.
.
76
why is the explosion of an atomic bomb considered as a chain reaction
neutrons produced by the splitting of atom strike
77
the first nuclear weapons testing was called
the manhattan project
78
nuclear medicine allows
to find illnesses and diseases
79
what is the title of richard feymans lecture in 1959
there’s plenty of room at the bottom
80
according to what law did the transistor sizes decreased
moores law
81
why is it so important to fabricate nanodevices in a clean room
it will result in defects
82
give examples of the commercial devices that contain nanosized materials
thermal insulation, self cleaning windows
83
how many atoms can you approx. hold in one nanometer
10
84
since when is it possible to manipulate individual atoms
1989
85
for the fabrication of nanomaterials which are the two possible approaches
top down , bottom up
86
because of their very large surface area nanocrystals can be used as catalysts
true
87
give three structures that are formed with only carbon atoms
carbon diamonds and nanotubes