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N5 CHEMISTRY > UNIT 1 > Flashcards

UNIT 1 Flashcards

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1
Q

What are the four indicators of a chemical reaction?

A

Colour change, effervescence, precipitation, temperature change

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2
Q

What is a reactant?

A

a substance that is involved in a chemical reaction and becomes changed

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3
Q

What is a product?

A

the substances produced in a chemical reaction

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4
Q

What is an exothermic reaction?

A

A reaction where heat energy is released to its surroundings

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5
Q

What is an endothermic reaction?

A

A reaction where heat energy is absorbed into the reaction from its surroundings

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6
Q

in an endothermic reaction..

A

the reactants have less energy than the products

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7
Q

in an exothermic reaction..

A

the reactants hold more energy than the products

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8
Q

What are the four factors affecting reaction rate?

A

temperature, concentration, particle size, use of a catalyst

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9
Q

Rates of reactants can be measured by..

A

changes in the concentration of the reactants or products, changes in the mass of the reactants or products, changes in the volume of the reactants or products

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10
Q

Properties of electrons

A

mass of 0 a.m.u
found in the energy levels
have a charge of -1

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11
Q

properties of protons

A

have a mass of 1 a.m.u
found in the nucleus
have a charge of +1

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12
Q

Properties of a neutron

A

mass of 1 a.m.u
found in the nucleus
charge of 0

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13
Q

why does every atom have a neutral charge?

A

they have the same number of positive protons as negative electrons. These opposite charges cancel each other out making the atom neutral.

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14
Q

Why do elements in the same group have similar chemical properties?

A

because they have the same number of outer electrons and the same valency

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15
Q

Valency

A

the number of unpaired electrons in the outer electron shell of an atom

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16
Q

Alkali metals

A

Metals that are in group one of the periodic table, when reacted with water they become alkalis and produce hydrogen gas, the metals become more reactive as you go down the group

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17
Q

Halogens

A

elements in group 7 and as you go down the group they become less reactive

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18
Q

Noble gasses

A

Elements in group 8 and are very unreactive

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19
Q

What does the atomic number tell you?

A

the amount of protons and electrons in an element

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20
Q

how to calculate the mass number

A

m=p+n

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21
Q

how to calculate the number of neutrons

A

n=m-p

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22
Q

what is an isotope

A

an atom with the same atomic number but different mass numbers

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23
Q

why do atoms form bonds?

A

to achieve a stable electron arrangement

24
Q

covalent bonding

A

A covalent bond is a shared pair of electrons between atoms of two non-metal elements.

25
Q

properties of covalent network bonds

A

very high mp and bp, strong bonds, graphite, boron, silicon and carbon are examples

26
Q

covalent molecular properties

A

usually liquids at room temperature, weak bonds, low mp and bp,

27
Q

ionic bonding

A

the electrostatic force of attraction between a positively charged metal ion and a negatively charged non-metal ion.

28
Q

pH scale

A

determines how acidic or alkaline a solution is

29
Q

Acids pH

A

pH of less than 7

30
Q

alkali pH

A

pH of more than 7

31
Q

neutral solutions pH

A

pH of exactly 7 water is an example

32
Q

What does the pH measure

A

the concentration of hydrogen ions in a solution

33
Q

Alkalis

A

soluble bases and are formed when a metal oxide, metal carbonate or a metal hydroxide is dissolves in water

34
Q

Acids

A

an acidic solution that is formed when a non metal oxide is dissolved in water

35
Q

why can acidic and alkaline solutions conduct electricity?

A

because they have ions that are free to carry charge

36
Q

equilibrium

A

water molecules breaking down hydroxide ions into hydrogen ions, a reversible reaction, present in all aqueous solutions

37
Q

Acidic solutions contain

A

more hydrogen ions than hydroxide ions

38
Q

Alkaline solutions contain

A

more hydroxide ions than hydrogen

39
Q

what is neutralisation?

A

the reaction of an acid with a base that results in the pH moving towards 7

40
Q

Equations for neutralisation

A

Acid+ alkali —-> salt+water

Acid+ metal oxide —–> salt+water

41
Q

Naming Acids

A

the metal ion from the alkali (or base) replaces the hydrogen ion from the acid,
Hydrochloric acid+ sodium hydroxide —> sodium chloride+ water+ carbon dioxide

42
Q

what is a spectator ion?

A

ions that are present during the reaction but are unchanged by the reaction

43
Q

what is a titration used for?

A

to accurately measure the volume of acid and alkali that react in neutralisation reactions

44
Q

known concentration in a titration

A

titrant

45
Q

Difference between the starting volume and end volume in a titration

A

titre

46
Q

pipette

A

allows you to add a precise amount of an acid or alkali to your empty conical flask

47
Q

phenothaline

A

indicator that can be used in titrations

turns water from pink to clear again when solutions neutralised

48
Q

how do you ensure accuracy during a titration

A

make sure conical flask is places under a white tile after indicator is added, this allows you to see the indicator clearly.
burette should not be filled above eyelevel to stop acid from tipping onto you and for an accurate measurement.
reading should be taken from the bottom of the meniscus

49
Q

end point

A

the point in which the titration is neutralised and solution has turned from pink to clear

50
Q

titration equation

A

when doing a titration repeat the experiment and take a note each time of the volume left to make sure the titre volume is consistent they should be within 0.2cm of each other

average titre = all titre volumes added together/ number of readings that were taken

rough volume not used to calculate average titre

51
Q

concordant

A

titre results that are within 0.2cm of each other

52
Q

Give 2 advantages of neutralising with a metal carbonate instead of a metal oxide

A

Reaction rate is high enough that acid doesn’t need to be heated
Easier end point detection due to evolution of CO2

53
Q

What is a Base?

A

A substance that neutralises an acid

54
Q

Why can acids never have zero OH- (aq) ions present?

A

Because acids are aqueous solutions and the dissociation of water means some OH- ions must be present

55
Q

Why can alkalis never have zero H+ (aq) ions present

A

Because alkalis are aqueous solutions and the dissociation of water means some H+ ions must be present

N5 CHEMISTRY (2 decks)

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