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Unit 3 Applied Science May exam Notes 2024
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Unit 3 Applied Science May exam Notes 2024
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1BTEC Applied Science
Unit 3 – Science Investigation Skills Transition
Booklet
Key Concepts to Unit 3 Learning Aims A-C
Name: …………………………………………………………
Learning Aim A – Planning an investigation
Writing a hypothesis for investigations – A1
Hypothesise are made as a starting point for an investigation and can be changed as further
investigations are carried out and the subject is taken forward.
A hypothesis is a prediction (often an assumption based on current knowledge and evidence)
of what you expect to see in your results.
A null hypothesis is a prediction (where you might not expect to find a particular trend or
pattern) which states that any recorded/observed differences between two or more data sets
is due to chance. A null hypothesis is tested by analysing results statistically. If the null
hypothesis is rejected, this indicates that there is a statistically significant difference (which
can be explored/explained with science).
NOW YOUR TURN
A1 – Writing a Hypothesis and Null Hypothesis
1. How could you write a hypothesis to the following experiment:
Metal powers react with copper sulphate solution in displacement reactions to produce
a new metal salt. This reaction releases heat energy which be measured and used to
determine the reactivity of the metal from the periodic table.
2. How could you write a null hypothesis to the following experiment:
Dove soap and Dettol soap are both usefully for hand-washing. Paper discs can be
diffused/soaked with different soap solutions and placed onto agar plates which have
been inoculated with bacteria. After incubating the plates, clear areas of no bacterial
growth can be measured (zones of inhibition). The larger the zone of inhibition, the
greater the effect of each soap on killing bacteria.
Use of equipment, techniques and procedures – justification – A2
Precision – the precision of equipment is inversely proportional to the unit size, i.e. the
smaller the unit, the more precise it is.
, 2
(In length measurements, µm units are more precise than mm units – because 1mm =
1,000µm)
Accuracy – the accuracy of equipment is dependent upon the percentage error. This
can be calculated using the following formula:
Absolute error is an accuracy equal to +/- half of the smallest unit marked on the scale of the
measuring device.
(A ruler measuring only in 1cm intervals is less accurate than a ruler measuring in 1mm
intervals – 1cm = 0.5cm or 5mm is absolute error, 1mm = 0.5mm is absolute error)
, 3
NOW YOUR TURN
A2 – Justifying equipment, A3 – Health and safety, A4 – Variables and A5 –
Methods
1. Compare the term ‘precision’ when choosing equipment vs. analysing results.
2. Put these units of measurement in order of their precision. mm, m, cm, nm, km,
µm
3. Comment on the precision of these results.
10, 12, 11, 18, 19, 20
4. Compare the term ‘accuracy’ when choosing equipment vs. analysing results.
5. Calculate the percentage error for the following measurements:
a. A 30cm has 0.1cm divisions. A plant leaf measures 26cm.
b. A balance reading goes to 0.01g. A precipitate weighs 5.68g
c. A measuring cylinder has 1ml divisions. A collection of rainwater goes to 67ml.
d. A thermometer measures to 1°C. When a temperature rise is measured, two
separate readings are taken so both readings could be out. A temperature rise of 7°C was
measured.
6. Describe how using a burette instead of a measuring cylinder for volume can
improve accuracy.
7. You carry out an investigation to study the effect of temperature on the rate of
reaction between magnesium ribbon and hydrochloric acid. Complete a risk assessment
including the following:
a. Identify two hazards
b. Describe the risks associated with these two hazards
c. What can you do to minimise these two risks
8. For the experiment described in Q7, identify:
a. The independent variable
b. The dependent variable
c. The control variable(s)
d. Any confounding variable(s)
9. Describe how the reliability of an investigation can be increased. (Refer to
anomalous results in your answer).
10. Describe how the validity of an investigations conclusions can be upheld.
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