Amount Of Substance

Question 1

What is relative atomic mass

Answer 1

The relative atomic mass, Ar, is the weighed average mass of an atom of an element taking into account its naturally occurring isotopes, relative to 1/12th the relative atomic mass of an atom of carbon 12

Question 2

What is the formula to work out the relative atomic mass

Answer 2

Average mass of one atom X 12

Question 3

What is the relative molecular mass

Answer 3

The relative molecular mass, Mr, of a molecule is the mass of that molecule compared to 1/12th the remit I’ve atomic mass of an atom of carbon - 12

Question 4

How do you find the relative molecular mass

Answer 4

By adding up all of the trait I’ve atomic masses of the atoms present in the molecule

Question 5

What is relative formula mass used for ??

Answer 5

Ionic compounds

Question 6

What is the definition for the Avogadro constant or Avogadro number

Answer 6

It is the number of atoms in 12g of carbon - 12

Question 7

What is the Avogadro constant written as

Answer 7

6.022 X10(23)

Question 8

What is a mole

Answer 8

The amount of a substance that contains 6.022X10(23) particles

Question 9

What is the formula to find out the number of moles present using Mr and mass

Answer 9

Number of moles = mass (g) devided by the Mr

Question 10

What is the ideal gas equation

Answer 10

PV=nRT

Question 11

In the ideal gas equation what must be used as the unit for pressure

Answer 11

Pa

Nm-2

Question 12

In the ideal gas equation what must be used as the unit for volume

Answer 12

M3

Metres cubed

Question 13

In the ideal gas equation what must be used as the unit for temperature

Answer 13

K

Kelvins

Question 14

In the ideal gas equation what is the unit of R

Answer 14

8. 31

8. 31JK-1 mol-1

Question 15

How do you convert from the volume unit dm3 to m3

Answer 15

Dm3

—

Question 16

How do you convert from the volume unit cm3 to m3

Answer 16

Cm3

—

Question 17

How do you convert from the unit of pressure kpa to pa

Answer 17

Kpa X 1000 = pa

Question 18

How do you convert from the pressure unit mpa to pa

Answer 18

MPa X 1000000 = pa

Question 19

How do you convert from the temperature unit degrees to kelvins

Answer 19

^C + 273 = K

Question 20

How do you find out the number of moles using the consecration and volume

Answer 20

C x V

Question 21

How do you work out the apparatus uncertainty

Answer 21

Error intervals decided by measurement

Question 22

How many particles does one mole contain

Answer 22

6.02x1023

Question 23

What is the formula for the number of particles

Answer 23

Number of particles = number of moles x Avogadro’s constant

Question 24

What mass of sodium hydroxide (NaOH) needs to be dellolved in water to give 50 cm3 of a solution with a concentration or 2 Moldm-3 ?
Discribe the steps to work this out

Answer 24

1) converts the volume to dm3 (50/1000 = 0.5 dm3)
2) work out the number of moles of NaOH (2 mol dm x 0.05 dm3 = 0.1 )
3) work out the Mr of NaOH (23 + 16 + 1 = 40)
4) mass = number of moles x mr ( 0.1 x 40 = 4)

Question 25

What are ionic equations

Answer 25

Equations that show only the reacting particles

Question 26

What does making a standard solution involve

Answer 26

Dissolving a known amount of solid in a known amount of water to create a known concentration

Question 27

What is a standard solution

Answer 27

A solution you know the exact concentration of

Question 28

Describe the steps to make a standard solution

Answer 28

1) work out how many moles of the substance you need (m=cxv) 2) work out how many grams of substance you need(ma=molxmr) 3) weigh by measuring the beaker then beaker with solid and take away mass of the beaker 4) add distilled water to dissolve 5) pour into volumetric flask (use funnel) rising beaker and rod 6) top the flask up to the correct volume 7) add stopper and mix a bit more

Question 29

What do titrations help you find out

Answer 29

Exactly how much acid is needed to neutralise a measured quantity of alkali (or vis versa)

Question 30

How would you use a pipette to measure the volume of the solution

Answer 30

1) use the pipette to measure the set volume of solution 2) put in a flask 3) add a few drops of indicator 4) fill the burette with the standard solution (using a funnel) 5) take the funnel out of top of burette when finished

Question 31

What are the two indicators used

Answer 31

Methyl orange | Phenolphthalein

Question 32

What are the colours that the indicator methyl orange goes

Answer 32

Red in an acid and yellow in an alkali

Question 33

What colours does the indicator phenolphthalein go

Answer 33

Colourless in acid | Pink in alkali

Question 34

How do you calculate the concentration from a titration

Answer 34

1) write a balanced equation and decide what you need to know 2) work out the moles of the one you know enough info for 3) what is the ratio for the reaction if the ratio is 1:1 the moles are the same 4) work out the concentration

Question 35

How would you work out the volume from a titration reaction

Answer 35

1) write a balanced equation 2) work out the moles of what you know 3) work out the ratio and therefor the other moles 4) work out the volume

Question 36

How do you work out the empirical mass

Answer 36

You add together the total mass form the all the empirical formulas

Question 37

How do you work out the theoretical formula

Answer 37

Theoretical yeald = moles x mr

Question 38

What is the percentage yeald formula

Answer 38

Actual yield dividied by the theoretical yield times 100

Question 39

What is the atom economy formula

Answer 39

Molecular mass of desired product divided by the mass of atoms in reactions times 100

Question 40

Explain what equation you would do. Calculate the mass in kg, of a single 52Cr ion assume that the mass of the 52Cr+ is n is the same as that of a 52Cr atom (Avogadro constant = 6.022X10(-26))

Answer 40

(52/ 1000) divided by the Avogadro constant