Paper 6 practical test

Question 1

define true value

Answer 1

value you get in an ideal experiment

Question 2

define measurement error

Answer 2

diff btw measured value and true value

Question 3

define accuracy

Answer 3

how close measurement is to true value

Question 4

define precision

Answer 4

-how close the reading are to each other
-how detailed the values are

Question 5

define reliability

Answer 5

variations btw values is small; produce consistent result
eg. repeat experiment multiple times

Question 6

define repeatability

Answer 6

if you can get same result when doing the same experiment again

Question 7

define reproducibility

Answer 7

if you can get same results when doing a diff experiment

Question 8

define validity

Answer 8

experiment is fair or not
have controlled variables

Question 9

define range

Answer 9

max and minimum values of the variables

Question 10

define anomaly

Answer 10

value which is outside of general pattern of values

Question 11

define dependent variables

Answer 11

-what you measure
-x axis
-left of table

Question 12

define independent variable

Answer 12

-what you change
-y axis
-right of table

Question 13

define control variables

Answer 13

-what you keep the same
-helps with comparison
-for validity

Question 14

how to increase reliability

Answer 14

-take minimum 3 readings and find mean
-repeat experiment and find mean value
-make sure rest of variables are controlled

Question 15

how to increase accuracy

Answer 15

-use proper apparatus
-use correct method when using apparatus
-repeat readings
-take readings at smaller intervals and find mean

Question 16

how to increase precision

Answer 16

-like more decimal place (eg. 3.2 is more precise than 3)
-use proper apparatus (more suitable ones)
-raw value is more precise than mean value

Question 17

what is amount used for

Answer 17

-time
-energy
-money

Question 18

what word do you use for liquid

Answer 18

-volume
-ml
-cm^3

Question 19

what word do you use for countable things

Answer 19

number

Question 20

what word do you use for like measuring solute is solvent (eg. salt in water)

Answer 20

-concentration
-mol/ dm^3
-%

Question 21

what word do you use for measure mass

Answer 21

-mass
-kg
-g

Question 22

percentage change formula

Answer 22

final - initial
——————- X 100%
initial

Question 23

rules for drawing graphs

Answer 23

-independent variable - x axis
-dependent variable - y axis
-x & y axis must be labeled with units
-draw the line of best fit- curve or straight
-scale must be even on both side
-use up more than half of the paper on both sides ( x & y)
-plot using “x” - has to be in middle of 4 boxes

Question 24

how do you calculate gradient

Answer 24

-rise over run (hypothenuse)
-in 3 sf

Question 25

why is repeating and finding mean reliable

Answer 25

identifies anomalies

Question 26

note: same decimal place in table & units in heading

Question 27

why does a reaction stop

Answer 27

-the reactants are used up

Question 28

define validity

Answer 28

how appropriate an experimental method is to achieve the aim of the experiment