5. formulae, equations and amounr of subtance (as)

Question 1

what is a mole

Answer 1

a unit for amount of a substance

Question 2

6.02 x 10^23 what does that represent

Answer 2

what are the number of particles in one molecule (avogadros constant )

Question 3

molar mass def

Answer 3

(MR) mass per mole of something

Question 4

number of moles =

Answer 4

mass of substance/ molar mass

Question 5

concentration of a solution def + unit

Answer 5

how many moles are dissolves per 1 dm^3

mol/dm3

Question 6

number of moles = from con

Answer 6

concentration (mol/dm3) x volume (dm3)

Question 7

mass of substance = from con

Answer 7

concentration (g/dm3) x volume (dm3)

Question 8

concentration of solution second measurement

Answer 8

how many grams of a substance are dissolves per 1dm3 of the solution g/dm3

Question 9

empirical formula def

Answer 9

smallest whole no ration of atoms of each element in a compound

Question 10

molecular formula def

Answer 10

the actual number of atoms of each type of element in a molecule

Question 11

empirical formula calculated

ex

4.4g of co2 1.8g of water made empirical formula of hydrocarbon

Answer 11

no of moles of co2- mass/ mr = 0.10

no moles of hydrogen- mass/ mr 0.20

ratio

c:h 1:2 ,, ch2

Question 12

balanced equation def

Answer 12

same number of each atom on both sides

Question 13

state symbols show

Answer 13

state of matter of things are in

Question 14

state symbols

Answer 14

solid s
liquid l
gas g
aqueous ( solution in water) aq

Question 15

displacement reaction

Answer 15

a more reactive element reacts to take the place of a less reactive element in a compound

Question 16

base reacts with acids

Answer 16

salt and water produced sometimes co2

Question 17

under the same condition

Answer 17

gases take up the same volume

Question 18

molar gas volume def + unit

Answer 18

the space that one mole of gas occupies at a certain temp or pressure dm3/mol

Question 19

24dm3/mol at what temp and pressure

Answer 19

room temp + pressure
rtp- 293k
20 celsius
101.3 kpa

Question 20

standard temp and pressure stp the molar gas volume 22.4 dm3/mol

Answer 20

stp 273 k
0 celsius
101.3kpa

Question 21

number of moles from molar gas

Answer 21

volume (dm3)/ molar gas volume

Question 22

how to measure molar volume of a gas

Answer 22

• find vol of gas by collecting gas that’s produced in gas syringe or by displacing water from a measuring cylinder

Question 23

ideal gas equation

Answer 23

pv = nrt
p= pressure (pa)
v=volume (m3)
n=number of moles
r= 8.31j/k/mol
t= temp (k)

Question 24

kelvins calculate

Answer 24

celsius + 273

Question 25

molar mass of an unknown volatile liquid how to calculate

Answer 25

put a known mass of liquid into a flask attach to sealed gas syringe warm gently in water bath until liquid evaporates record volume of gas in syringe and temp of water bath use ideal gas equation to work out how many moles of liquid were in sample

Question 26

molar mass = from moles

Answer 26

mass/moles

Question 27

titrations used

Answer 27

to find a conc of acid or alkali solutions

Question 28

hazard def + risk associated w it

Answer 28

anything that has the potential to cause harm or damage probability of someone being harmed if they’re exposed to hazard

Question 29

risk assessment

Answer 29

identifying all hazard + risk of it and how likely it is that something could go wrong and how serious it is if it did and ways to reduce risk

Question 30

standard solution

Answer 30

has known concentration

Question 31

how to make a standard solution

Answer 31

Woke out how many moles of solute you need mol=con x vol/1000 how many grams of solute needed mass = moles x molar mass weigh out mass of solute using a balance weigh first weighing vessel add solid acid to beaker add 100cm3 of distilled water and stir until solute dissolved reweigh weighing vessel to see how much had been added tip solution into volumetric flask rinse beaker and stirring rod w distilled water and add that to the flask too add more distilled water to line stopper the bottle and turn upside down a few times to make sure it’s all mixed

Question 32

methyl orange

Answer 32

turns yellow red when adding acid to alkali

Question 33

phenolphthalein

Answer 33

red to colourless when adding acid to alkali

Question 34

titration show

Answer 34

how much acid needed to neutralise a quantity of alkali

Question 35

acid base titration steps

Answer 35

measure alkali of unknown conc add indicator rinse burette w standard solution of acid then fill it w standard solution do a rough titration then an accurate one swirl work out amount of acid used to neutralise the alkali (final reading - initial reading) volume = titre repeat until concordat results

Question 36

pipette

Answer 36

measures only one volume of solution

Question 37

burette

Answer 37

measures different volumes and lets you add the solution drop by drop

Question 38

uncertainty

Answer 38

amount of error your measurements might have

Question 39

any measurements you make have uncertainty in them due to

Answer 39

the limits to then sensitivity of the equipment used

Question 40

what does the +- sign tell you in uncertainty

Answer 40

the range in which the true value could lie called the margin of error

Question 41

uncertainty calculate

Answer 41

calculate range /2

Question 42

percentage uncertainty

Answer 42

uncertainty/ reading x 100

Question 43

ways to minimise percentage uncertainty

Answer 43

use the most precise equipment you can plan to improve your results

Question 44

errors can be

Answer 44

systematic or random

Question 45

systematic errors

Answer 45

can be the same very time you repeat the experiment could be by the way you set up the equipment

Question 46

random error

Answer 46

be different each time you repeat the experiment

Question 47

repeating experiment and finding mean of results

Answer 47

helps deal with random errors but won’t help systematic errors be more accurate

Question 48

kpa to pa

Answer 48

x 10^3

Question 49

cm^3 to m^3

Answer 49

x10^-6 or divide by 10^6

Question 50

dm^3 to m^3

Answer 50

divide by 10^3 or x10^-3

Question 51

celcius to k

Answer 51

add 273

Question 52

percentage yield

Answer 52

actual yield / theoretical yield x 100

Question 53

atom economy

Answer 53

molar mass of desired products/ sum of molar masses of all products x 100