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chapter tests > Chemistry chapter 1 > Flashcards

Chemistry chapter 1 Flashcards

1
Q

what does the empirical formula show

A

The empirical formula shows the actual number of ions bonded together therefore they are used for giant structures such as ionic compounds and giant covalent compounds

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2
Q

what does the molecular formula show

A

The molecular formula is for compounds that exist as simple molecules, it tells you the number of each type of atom that makes up a molecule, on the other hand it does not tell you the order in which the atoms are bonded to each other

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3
Q

what is Avogadro hypothesis

A

Under the same conditions of temperature and pressure a mole of any gas would fill the same volume of space

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4
Q

why is Avogadro’s hypothesis important

A
  • This is important as we can compare the number of molecules in different gases by comparing their volumes and it does not matter which type of gas is being studied, by measuring the volume we are counting the molecules
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5
Q

why does the difference in individual particles have no effect in Avogadro’s hypothesis

A
  • The difference in the individual particles have no effect on overall volume because the particles are so spread out that any differences become unimportant
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6
Q

what is the ideal gas equation and what can it be used to find

A

-The relationship between the volume, pressure, temperature and number of moles of an ideal gas can be described by the ideal gas equation
It can be used to find out how the pressure of gases will change as temperatures and number of moles vary

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7
Q

the ideal gas equation

A
  • They are in continuous motion and do not experience any intermolecular forces
  • They exert pressure when they collide with each other and the walls of the containers
  • All collisions between gas molecules and between gas molecules and container walls are elastic therefore they do not cause kinetic energy to be lost
  • Gas molecules are so small compared to the size of any container they are found in that any difference in sizes of different gas molecules can be ignored
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8
Q

what does the concentration tell you

A
  • The concentration of a solution tells you how much solute is dissolved in a given amount of solvent
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9
Q

what is a standard solution

A

it has a known concentration

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10
Q

how do you make a standard solution

A
  • To make a standard solution you need to know the concentration and volume of the solution you need to make, work out the amount, in mole, of solute needed, convert this amount of solute into a mass, in g, so that you know how much to weigh out
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11
Q

what does concentrated mean

A

a large amount of solute per dm3

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12
Q

what does dilute mean

A

a small amount of solute per dm3

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13
Q

what does stoichiometry and reacting quantities tell study

A
  • It studies the amounts of substances that are involved in a chemical reaction
  • you use a balanced chemical reaction to find the stoichiometry of a reaction
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14
Q

what does stoichiometry and reacting quantites tell us

A
  • it tells you the number of moles of each species that will react together
  • the moles of each product are formed
  • the reacting quantities that are needed to prepare a required quantity of a product
  • the quantities of products formed by reacting together know quantities of reactants
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15
Q

why is the percentage yield never 100%

A
  • the reaction may be at equilibrium and may not got to completion
  • side reactions may occur leading to by-products
  • reactants may not be pure
  • some of the reactants or products may be left behind in the apparatus used in the experiment
  • separation and purification may result in the loss of some of the product
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16
Q

what is a species

A
  • A species is a type of particle that takes part in a reaction, it could be an atom, ion, molecule, empirical formula or electron
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17
Q

what do we do with the by-products

A
  • have to be disposed of as they are considered waste
  • costly and has environmental disadvantages
  • wastes valuable resources
  • may be sold elsewhere and used in the chemical plant
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18
Q

how can atom economy benefit society

A
  • use processes with a higher atom economy we can reduce the amount of waste produced
  • reduce total expenditure of a chemical company
  • more sustainable
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19
Q

what are addition reactions

A

addition reactions involve 2 or more reactants joining together, the atom economy for addition reactions is always 100%

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20
Q

what are substitution reactions

A

substitution reactions involve an atom or molecule “swapping places” with another, the atom economy for substitution reactions is always less than 100%

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21
Q

what are elimination reactions

A

elimination reactions involve the removal of a small molecule, usually water, from another molecule, the atom economy of elimination reactions is always less than 100%

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22
Q

acids in aqueous solutions

A
  • when an acid is added to water the acid releases H+ ions into the solution, the H+ ion is the active ingredient in acids,
  • an acid is a proton donor
23
Q

acids and dissociations

A
  • strong acids are very good at giving up H+ ions so they are fully or almost fully dissociate
  • weak acids are not good at giving up these ions so once released from weak acids they are quickly taken back again therefore they only partially dissociate
24
Q

bases

A
  • a base is the opposite of an acid as they neutralise acids,
  • a base is a proton, H+, acceptor
25
Q

alkalis

A
  • Ph greater than 7 when dissolved in water they release OH-
  • They are very corrosive
26
Q

ammonia as a weak base

A
  • Ammonia is a gas that dissolves in water to form a weak alkaline solution
  • It’s a weak base as only a small proportion of the dissolved NH3 reacts with water
27
Q

what features does a salt have

A
  • The positive ion (cation) in usually a metal ion or ammonium ion
  • The negative ion(anion) in a salt derived from an acid
  • The formula of a salt is the same as that of a parent acid expect that an H+ ion has been replaced by the positive ion
28
Q

how can salts form

A
  • Salts can be produced by neutralising acids with bases
  • A second equation – ionic equation – shows the important role of the H+ ion in the reaction, the H+ ions react with the OH- ions and neutralise form water
29
Q

what is ammonium nitrate found as

A
  • When ammonium nitrate is in solution it is found as two ions NH4+ and NO3
30
Q

why are some compounds hydrated

A
  • If a compound d crystallises within water the water can become part of the crystalline structure this is called water of crystalisation
31
Q

titration stuff we need to know

A
  • Wash burette with distilled water and then the acid
  • Wash pipette with distilled water then the sodium hydroxide solution
  • Wash the conical flask with water
  • Touch the tip of the pipette on the surface of the liquid to ensure the transfer of the correct quantity of sodium hydroxide
  • Ensure no spillage of liquid during the transfer of the sodium hydroxide in the pipette into the conical flask
  • Add no more than 5 drops of indicator
  • Read the burette to the bottom of the meniscus
  • Read the burette to the nearest 0.05cm3
  • Carry out a rough titration to get an approximate titre
  • When nearing the equivalent point add the acid a single drop at a time
  • Make sure the tip of the burette and the sides of the conical are rinsed with distilled water between the addition of each drop
  • Swirl the conical flask to ensure complete mixing of the acid and the sodium hydroxide
  • Repeat titrations until two concordant results are obtained within 0.1cm3 of each other
32
Q

what are indicators used for

A
  • They are used to identify the end point and the indicator must be a different colour in the acidic solution than in the basic solution
33
Q

methyl organge

A

colour in acid - red
colour in base - yellow
end point colour -orange

34
Q

Bromothymol blue

A

colour in acid - yellow
colour in base blue
end point colour - green

35
Q

phenolphthalein

A

colour in acid - colourless
colour in base - pink
end point colour - pale pink

36
Q

Why is ammonia able to react with acid?

A

When it dissolves in water it forms a weak alkaline solution
NH3+H2O = NH4+ + OH-

37
Q

Describe amphoteric substances

A

when substances are both acids and bases for example glycine, the COOH end is an acid and donates a proton whereas the H2N end is a base and accepts a proton

38
Q

What are oxidation numbers used for

A

used to keep track of how electrons are used in bonding

39
Q

what is the oxidation number

A

number of electrons that at an atom uses to bond with atoms of another electron

40
Q

what are the rules for oxidation numbers

A 
uncombined element= 0
combined oxygen = -2
combined oxygen in peroxides = -1
combined hydrogen= +1
combined hydrogen in metal hydrides= -1
simple ion = charge on ion
combined fluorine = -1
41
Q

What are oxyanions

A

negative ions that contain an element along with oxygen for example SO4 2- they usually end in -ate

42
Q

Define oxidation

A
  • gain of oxygen
  • loss of hydrogen
    -loss of electrons
    these are reducing agents
43
Q

Define reduction

A
  • loss of oxygen
  • gain of hydrogen
  • gain of electrons
    these are oxidising agents
44
Q

What is a redox reaction

A

a redox reaction is where both oxidation and reduction take place

45
Q

example of an oxidation equation

A

see card

46
Q

example of reduction equation

A

see card

47
Q

How do metals behave in a redox reaction

A

metals are oxidised

  • loose electrons
  • form positive ions
48
Q

How do non-metals behave in a redox reaction

A

non-metals are reduced

  • gain electrons
  • form negative ions
49
Q

what are the oxidation numbers do in redox reaction

A 
reduction = decrease in oxidation number
oxidation = increase in oxidation number
50
Q

what does an acid have to react with to become a redox reaction

A

metals, they form a salt and hydrogen

51
Q

Name 2 uses of mass spectrometry

A
  • the determination of relative isotopic masses and relative abundances of the isotope
  • calculation of the relative atomic mass of an element from the relative abundances of its isotopes
52
Q

What are the formulae of the common acids

A

HCl
H2SO4
HNO3
CH3COOH

53
Q

What are the formula of the common alkalis

A

NaOH
KOH
NH3

chapter tests (8 decks)

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