PAG 12 - Research skills Flashcards
What is a prediction using scientific
knowledge called?
Hypothesis
What is meant by the term accuracy?
How close the measurement is to the
true value
What are variables?
Factors that can affect the outcome of
the experiment
What is an independent variable?
A factor that is changed during the
experiment to see the effect it has on
another factor.
What is a dependent variable?
A factor that is measured or observed in
the experiment.
What is a control variable?
A factor that is kept constant throughout
the experiment.
What is oxidation?
The loss of electrons or increase in
oxidation state
What is reduction?
The gain of electrons or decrease in
oxidation state
What is a redox reaction?
A reaction in which some atoms are
oxidised and others are reduced
How can the percentage of iron in iron
tablets be found?
- Prepare a standard solution of iron (II) using the tablets and sulfuric acid
- Titrate a set volume of this iron(II) solution against a solution of KMnO4
- Repeat until you obtain concordant results and calculate a mean titre
- Calculate the number of moles of KMnO4
that reacted - Use the ratio in the chemical equation to calculate the number of moles of
iron that reacted - Calculate the percentage mass of iron using the mass present in the
standard solution
Describe how to make a standard
solution of acidified iron(II) sulfate
- Grind up some iron tablets. Measure the total mass of the iron tablets in a weighing
boat. - Add the powdered tablets to a conical flask and reweigh the weighing boat. The
difference between the masses is the mass of iron tablets in the solution. - Add a 50cm3
of sulfuric acid to the conical flask to dissolve the iron. Stopper the
flask and shake well. Leave the flask for the residue to settle. - Filter the solution into a volumetric flask without disturbing the residue. Rinse the
filter paper with a small volume of distilled water. - Fill the volumetric flask up to the graduation mark with sulfuric acid then stopper
and invert the flask to mix.
Write an equation for the redox reaction between iron(II) ions and manganate(VII) ions
5Fe2+ + MnO4- + 8H+ → 5Fe3+ + Mn2+ + 4H2O
When making a standard solution, what
method should be used to find the mass
of solute?
Weighing-by-difference method
Why is an indicator not required in the
titration between Fe2+ and MnO4- ?
KMnO4
is self indicating; the end point is
when you get the first permanent pale
pink colour.
In a titration, what are concordant
results?
Titres that are within 0.1 cm3 of each
other.
Give 3 possible sources of error in this
experiment
- The iron may not completely dissolve - warming
may help - Some iron may not be transferred between
containers - take washings - The end point may be hard to see - place a white
tile underneath the conical flask to make the colour
change easier to observe
What equation links concentration, moles
and volume?
Moles = volume x concentration n = V x C
What equation links mass, molecular
mass and number of moles?
Mass (g) = molecular mass x mole
m = M x n
What is primary research?
A new set of data that has been
collected. Conclusions are drawn from
this new data.
Give two examples of primary research
Surveys
Experiments
What is secondary research?
Data from other studies that are used to
draw conclusions
What is the difference between
qualitative and quantitative data?
Qualitative - descriptions of observations
Quantitative - numerical data
Online and offline resources can be used
for what?
Research
Describe the Vancouver referencing
system
Full references are numbered at the end of a document (with numbers
linked to the appropriate reference in they order they appear in the text).
E.g. 1. Author (year of publication), title
Other information such as the page number, volume/ issue number, web
address or date of access (online only) may also need to be recorded.
