UNIT 1

Question 1

What are the four indicators of a chemical reaction?

Answer 1

Colour change, effervescence, precipitation, temperature change

Question 2

What is a reactant?

Answer 2

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

Question 3

What is a product?

Answer 3

the substances produced in a chemical reaction

Question 4

What is an exothermic reaction?

Answer 4

A reaction where heat energy is released to its surroundings

Question 5

What is an endothermic reaction?

Answer 5

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

Question 6

in an endothermic reaction..

Answer 6

the reactants have less energy than the products

Question 7

in an exothermic reaction..

Answer 7

the reactants hold more energy than the products

Question 8

What are the four factors affecting reaction rate?

Answer 8

temperature, concentration, particle size, use of a catalyst

Question 9

Rates of reactants can be measured by..

Answer 9

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

Question 10

Properties of electrons

Answer 10

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

Question 11

properties of protons

Answer 11

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

Question 12

Properties of a neutron

Answer 12

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

Question 13

why does every atom have a neutral charge?

Answer 13

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

Question 14

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

Answer 14

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

Question 15

Valency

Answer 15

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

Question 16

Alkali metals

Answer 16

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

Question 17

Halogens

Answer 17

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

Question 18

Noble gasses

Answer 18

Elements in group 8 and are very unreactive

Question 19

What does the atomic number tell you?

Answer 19

the amount of protons and electrons in an element

Question 20

how to calculate the mass number

Answer 20

m=p+n

Question 21

how to calculate the number of neutrons

Answer 21

n=m-p

Question 22

what is an isotope

Answer 22

an atom with the same atomic number but different mass numbers

Question 23

why do atoms form bonds?

Answer 23

to achieve a stable electron arrangement

Question 24

covalent bonding

Answer 24

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

Question 25

properties of covalent network bonds

Answer 25

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

Question 26

covalent molecular properties

Answer 26

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

Question 27

ionic bonding

Answer 27

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

Question 28

pH scale

Answer 28

determines how acidic or alkaline a solution is

Question 29

Acids pH

Answer 29

pH of less than 7

Question 30

alkali pH

Answer 30

pH of more than 7

Question 31

neutral solutions pH

Answer 31

pH of exactly 7 water is an example

Question 32

What does the pH measure

Answer 32

the concentration of hydrogen ions in a solution

Question 33

Alkalis

Answer 33

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

Question 34

Acids

Answer 34

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

Question 35

why can acidic and alkaline solutions conduct electricity?

Answer 35

because they have ions that are free to carry charge

Question 36

equilibrium

Answer 36

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

Question 37

Acidic solutions contain

Answer 37

more hydrogen ions than hydroxide ions

Question 38

Alkaline solutions contain

Answer 38

more hydroxide ions than hydrogen

Question 39

what is neutralisation?

Answer 39

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

Question 40

Equations for neutralisation

Answer 40

Acid+ alkali ----> salt+water | Acid+ metal oxide -----> salt+water

Question 41

Naming Acids

Answer 41

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

Question 42

what is a spectator ion?

Answer 42

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

Question 43

what is a titration used for?

Answer 43

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

Question 44

known concentration in a titration

Answer 44

titrant

Question 45

Difference between the starting volume and end volume in a titration

Answer 45

titre

Question 46

pipette

Answer 46

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

Question 47

phenothaline

Answer 47

indicator that can be used in titrations | turns water from pink to clear again when solutions neutralised

Question 48

how do you ensure accuracy during a titration

Answer 48

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

Question 49

end point

Answer 49

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

Question 50

titration equation

Answer 50

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

Question 51

concordant

Answer 51

titre results that are within 0.2cm of each other

Question 52

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

Answer 52

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

Question 53

What is a Base?

Answer 53

A substance that neutralises an acid

Question 54

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

Answer 54

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

Question 55

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

Answer 55

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