1.1 and 1.3 (formulae and chemical equations)

Question 1

what does aqueous mean?

Answer 1

dissolved in water

Question 2

What is the difference between copper sulphide and copper sulphate?

Answer 2

copper sulphate also has oxygen

Question 3

Define compound

Answer 3

two or more different elements that are chemically bonded in a fixed proportion

Question 4

what is a redox reaction?

Answer 4

a type of chemical reaction that involves a transfer of electrons between two species.

Question 5

What oxidation state (charge) does group 1 always have?

Answer 5

+1 oxidation state

Question 6

What oxidation state (charge) does group 2 always have?

Answer 6

+2 oxidation state

Question 7

What oxidation state (charge) does group 0 always have?

Answer 7

0 as they don’t react so don’t form ions

Question 8

What oxidation state (charge) does group 7 always have?

Answer 8

-1 oxidation state

Question 9

What oxidation state (charge) do transition metals have?

Answer 9

they have different oxidation states
eg Fe(II) and Fe(III)

Question 10

what does an oxidation agent do?

Answer 10

they will oxidise the other compound in the reaction

Question 11

what does a reducing agent do?

Answer 11

they will reduce the other compounds in the reaction

Question 12

what is the definition of electronegativity?

Answer 12

the ability of an element to attract a pair of electrons in a covalent bond

Question 13

what is ionic bonding?

Answer 13

the electrons transfer from metal to non-metal

Question 14

what is covalent bonding?

Answer 14

shared between atoms

Question 15

what is metallic bonding?

Answer 15

delocalised electrons

Question 16

when is the oxidation state of oxygen different?

Answer 16

in hydrogen peroxide and the xodiation state is -1

Question 17

what is the oxidation state of flourine always?

Answer 17

always -1

Question 18

what is meant by an isotope?

Answer 18

isotopes occur when atoms of the same element have different masses (i.e same number of protons, different number of neutrons)

Question 19

How do you calculate the percentage composition calculations?

Answer 19

mass of element ÷ mass of compound x 100

Question 20

define a mole

Answer 20

a mole is the amount of a substance in grams which has the same number of particles as there are atoms

Question 21

what is avogadro’s constant?

Answer 21

6.02 x 10^23

Question 22

what is the equation to work out mols?

Answer 22

mass divided by mr

Question 23

define the term atom economy

Answer 23

a measure of the amount of starting materials that end up as useful products

Question 24

how do you calculate the percentage atom economy?

Answer 24

relative formula mass of useful products divided by relative formula mass of all products x100

Question 25

how much is 1 tonne in kg?

Answer 25

1000kg

Question 26

how much is 1 tonne in g?

Answer 26

1,000,000g

Question 27

define density

Answer 27

measures the amount of mass per unit of volume in a substance

Question 28

calculate density

Answer 28

mass/volume

Question 29

what are the three steps when converting density to concentration?

Answer 29

step 1 - no. of mols that you have in a solution n= m÷mr step 2 - volume that the no. of mols is dissolved in v= m ÷ d step 3 - concentration c= n ÷ v

Question 30

what does the volume always have to be in when working out solutions?

Answer 30

dm3

Question 31

define concentration

Answer 31

the amount of a substance dissolved in another substance

Question 32

how do you get from gdm-3 to moldm-3?

Answer 32

÷mr

Question 33

how do you get from moldm-3 to gdm-3?

Answer 33

xmr

Question 34

how do you convert from the empirical formula to the molecular formula?

Answer 34

mr÷empirical mr

Question 35

when working out calculations involving solutions what are the two equations you must remember and what are all the units?

Answer 35

m = n x mr g = mol x no unit n = c x v mol = moldm-3 x dm3

Question 36

what are some sources of error when reading the burette/pipette in titrations?

Answer 36

ensure you read the solution at eye level allow the pipette to drain via gravity

Question 37

what are some sources of error when using indicators?

Answer 37

people percieve colours differently

Question 38

what are some sources of error when weighing solids?

Answer 38

residue could be left on the weighing scale/boat may be spillage

Question 39

what is the accuracy of a burette and how do you calculate the percentage error for it?

Answer 39

+/- 0.05cm3 2x0.05 / titre x100

Question 40

what is the accuracy of a 2 d.p mass balance and how do you calculate the percentage error for it?

Answer 40

+/- 0.005g 0.005/mass x100

Question 41

what is the accuracy of a 3 d.p balance and how do you calculate the percentage error for it?

Answer 41

+/- 0.0005g 0.0005/mass x 100

Question 42

What are the four steps in the determination of xH2O?

Answer 42

1. calculate mass of water removed 2. mass of dry salt 3. the moles of water and the moles of the hydrate 4. divide mols of water by hydrate

Question 43

How do you calculate percentage yield?

Answer 43

actual yield/theoretical yield x 100 (little/big)

Question 44

What does avogadro's law only apply to?

Answer 44

gases

Question 45

what is important to know about double titrations?

Answer 45

in the first stage of the titration (phenolphthalein colour change) relates to the concentration of the hydroxide and carbonate the second stage (methyl orange) relates to the conc of hydrogencarbonate

Question 46

what is avogadro's law?

Answer 46

equal volumes of gases at the same temperature and pressure contain equal numbers of molecules

Question 47

What is 1 mole of any gass at room temperature

Answer 47

24.5m3

Question 48

what is the difference between s.t.p and r.t.p? What is the volume of any gas at s.t.p?

Answer 48

room temperature and pressure (RTP) = 25 degrees celcius 298K and 1 atm (1.01x10^5 Pa) standard temperature and pressure STP = 0 degrees celsius 273K and 1 atm pressure

Question 49

what is the number of mols of a gas?

Answer 49

n = V/Vm

Question 50

what is the ideal gas equation? and what are they measured in?

Answer 50

V = (RnT) ÷ P or PV = nRT where P is in Pa V in m^3 n in mols T in K R is molar gas constant, 8.31Jmol-1K-1

Question 51

convert: KPa to Pa? 1m3 to dm3 1dm3 to cm3 m3 to cm3

Answer 51

x1000 1m3 = 1000dm3 1dm3 = 1000cm3 1m3 = 1,000,000

Question 52

what are volatile liquids?

Answer 52

liquids which turn into gas at not too high a temp

Question 53

how do you calculate the molar mass of a gas (modifying the ideal gas equation)?

Answer 53

PV = mRT ÷ mr or mr = mRT÷ PV

Question 54

what is Boyle's law?

Answer 54

P1 x V1 = P2 x V2 (assume temp is constant)

Question 55

what is Boyle's law when the temperature is not constant?

Answer 55

P1 x V1 ÷ T1 = P2 x V2 ÷ T2

Question 56

when a mass spectrometer is used to find the mr of an element what two things does it measure?

Answer 56

1. mass of each different isotope of the element 2. the relative abundance of each isotope of the element

Question 57

what are the four steps of a mass spectrometer?

Answer 57

1. ionisation 2. acceleration 3. deflection 4. detection

Question 58

what occurs in step one, ionisation?

Answer 58

vapourised sample passes into the ionisation chamber where the particles are bombarded w/a stream of electrons

Question 59

what occurs in step two, acceleration?

Answer 59

an electric field accelerates the positive ions to a high speed

Question 60

what occurs in step three, deflection?

Answer 60

different ions are deflected by a magnetic field by different amounts

Question 61

what does the amount of deflection depend on?

Answer 61

the mass of the ion, lighter ions will deflect more the charge of the ion, ions with two or more positive charges are deflected more

Question 62

what occurs in step four, detection?

Answer 62

beam of ions passing through the machine is detected electrically

Question 63

what are three other uses of mass spectroscopy?

Answer 63

- identifying unknown compounds eg testing athletes for drugs - identifying trace compounds in forensic science - analysing molecules in space