Data Analysis and Measurement Flashcards
What is accuracy and precision?
accuracy- refers to the closeness of the data values from the true values
precision- refers to how close the measurements or the data values are together
What ways can you ensure to get accurate values?
repeating measurements many times
repeating measurements w different instruments
using measuring instruments accurately
using measuring instruments carefully
What is the mean?
is the average of numbers taken from data in a number of identical experiments
What is the definition of standard deviation and its formula?
is a measure of spread out numbers are from the mean. Low values means data points are very close while high values mean they are spread out
Sn= square root of Σ(x-x̄)^2/n-1
Σ- summation
x̄- mean
x- individual piece of data
n- number of individual piece of data
What are 3 known errors that can take place in an experiment?
limitations of apparatus used
faults in laboratory equipment
mistakes in calculations
How to find the solution of a known concentration?
tip the solid of the weighed bottle in 200 cm3 beaker, add 50 cm3 of pure water, shake well until dissolved, wash out the volumetric flask w purewater, pour the solution from the beaker into the volumetric flask using a funnel, wash out the beaker several times and add the washings of the flash, wash the remaining liquid of the funner into volumetric flask w pure water, fill up volumetric flask just below the meniscus, add water until the meniscus reaches the calibration mark, put the stopper on the flask and shake gently
What can primary standards be used to do?
to find acid, bases, reducing or oxidising agents
What properties should primary standards have?
the solid must obtain a high density, must be stable in air, must be soluble in water and form a solution, must give readily results in a titration, preferably have a high relative molecular mass
What can a colorimetry be used for?
can be used to find the concentration of coloured solutions
