1. practicals

Question 1

variable

Answer 1

a quanity that has the potential to change

Question 2

independant variable

Answer 2

what you change

Question 3

dependant variable

Answer 3

what changes due to the independant change

Question 4

control variable

Answer 4

what stays the same

Question 5

Initial planning

Answer 5

step one - question , this is the aim of the experiment
step two - a prediction with a hypothesis
step 3 - identify variable
step 4 - method this includes risk factors

Question 6

risks and hazards

Answer 6

the dangers in the experiment.
risks - chance of it happening
hazard- the danger itself

Question 7

corrosive

Answer 7

can cause chemical burns to skin tissue -
use in low conc
wear protection e.g goggles

Question 8

irritant

Answer 8

causes inflammation and discomfort.
wear lab coat.
if chemical a gas do the experiment in a fume cupboard.
use in low concentration

Question 9

flammable

Answer 9

can set aflame easily .
keep away from naked flame
heat it in a water bath, sand bath or electrical heater rather than burnsen burner

Question 10

toxic

Answer 10

can cause illness/ fdeath

use little as possible and in low concentration.
if a gas do it in a fume cupboard.
wear protection.

Question 11

oxidising

Answer 11

reacts in presents of oxygen .
can ignite easily 
keep in solution rather than solid form 
keep away from combustible items 
use as little as possible.
keep it in an well ventilated area.

Question 12

Ways to measure ph

Answer 12

ph charts
ph meters
ph probe on a data logger

Question 13

ph charts

Answer 13

universal indicator is a substance that changes color according to ph

the give a good rough idea on ph value but the data produced is not concise.

Question 14

ph meters

Answer 14

an electronic gadget that gives a precise value of ph. the probe is [placed in the solution and the reading is displayed

Question 15

ph probe on a data logger

Answer 15

the ph probe can be connected to a data logger. this will record the reults so you can look back on them later. this is useful to show how ph could change.

Question 16

heating substances

Answer 16

water bath 
burnsen burner 
sand bath
electric heater 
heating under reflux

Question 17

water bath\

Answer 17

container that contains water. control the temp of water and submerge the mixure which will then be the same temperature as the water. this does not work if you want to heat something that is way higher than 100 c.

Question 18

sand bath

Answer 18

same as water but can go beyond 100 c

Question 19

electric heater

Answer 19

a metal [plate that is heated to desired temperature.

Question 20

heating under reflux

Answer 20

Heating under reflux involves heating with a condenser placed vertically in the flask to avoid loss of volatile substances. As in take propene for example- when it’s formed during en elimination reaction, it’s a gas which it passes through the condenser and can be collected.

Question 21

filtration under reduced pressure

Answer 21

when you want to keep the solid not liquid.

this is called the buchner funnel.

Question 22

filter paper

Answer 22

The steps to flute the filter paper are shown. First, fold
in half; open and fold in half at 90 to the first fold,
subsequently align adjacent folds and make new folds
bisecting the previous folds until a fan-like arrangement
is obtained. Pleat into a fan by folding each segment in
the opposite direction to its neighbours, in
accordion-like fashion. When opened out the complete
fan-like fluted paper results.
Fluting the filter paper maximises the rate at which the
liquid may flow through the filter paper by increasing the
surface area and by allowing air to enter the flask along
its sides to permit rapid pressure equalisation.

Question 23

discrete data

Answer 23

data with values typically found by counting

like shoe size

Question 24

continous data

Answer 24

you can never find the true value of continous data.

can have any value.

Question 25

catagoric data

Answer 25

can be sorted into catagories e.g.

blue red orange solution etc.

Question 26

ordinal data

Answer 26

similiar to catagoric data e.g. slow average fast etc.

Question 27

bar chart

Answer 27

catagoric or ordinal data

Question 28

pie chart

Answer 28

can display data

Question 29

scatter graph

Answer 29

continous data. shows a correlation with all of the results.

use line of best fit

Question 30

anolmies

Answer 30

usually due to error.

Question 31

correlation vs causation

Answer 31

just because there is a correlation it does not mean it is caused by it

Question 32

valid results

Answer 32

answers orginal question

Question 33

accurate results

Answer 33

really close to the answer

Question 34

precise results

Answer 34

small spread between data around mean helps to reduce random error

Question 35

repeatable results

Answer 35

you get the same results by repeating the same methods

Question 36

reproducible results

Answer 36

others get the same results from experiments

Question 37

uncertainity

Answer 37

errors due to the sensitivity of the equipment

Question 38

random error

Answer 38

Random errors in experimental measurements are caused by unknown and unpredictable changes in the experiment. These changes may occur in the measuring instruments or in the environmental conditions.
Examples of causes of random errors are:

electronic noise in the circuit of an electrical instrument,
irregular changes in the heat loss rate from a solar collector due to changes in the wind.

Question 39

systematic error

Answer 39

Systematic errors in experimental observations usually come from the measuring instruments. They may occur because:
there is something wrong with the instrument or its data handling system, or
because the instrument is wrongly used by the experimenter.