Unit 4 – scientific practical techniques
M1 – Explain how accuracy may be ensured in the techniques used
For the quantitative and qualitative tests carried out, accurate techniques were necessary as without
them, incorrect results would have been obtained. In each test carried out special equipment was
used as it enabled not only the techniques to be smooth and precise but also allowed the results to
be as close to accurate as possible.
In the qualitative test for starch, a spotting tile was used over test tubes for two reasons. One being
that the spotting tiles white base meant that any colour change could visually be seen against the
white background where as a test tube is clear and so human error could have been made. The
second reason being that all the different foods being tested could fit onto one spotting tile instead
of using 9 different test tubes. This meant less washing up was needed to be done but also meant
that the experiment was relatively safer as no glass was available to be broken.
In the qualitative test for lipids not only was the test tube shaken instead of waiting for fat droplets
to occur, but filter paper was used for solid foods. This overall meant less test tubes were being used
and regarding solid foods, a more accurate result was given. However, errors that occurred or could
occur with the use of spotting tiles is contamination. Due to the wells being so shallow, when
dropping each piece of food into their own well, for example the Tropicana juice, this food could
have easily splashed into another well causing contamination of that piece of food and possibly
giving incorrect results. Another way contamination could have occurred is by people getting mixed
up with the pipettes. Pipettes should only be used for one type of food as if one type of food was
picked up and then another, then the second piece of food and other pieces thereafter will be
contaminated with the ones before it automatically causing negative results.
In the qualitative test for cations we held the nichrome wire in the flame before testing each
unknown compound. This is because by doing this we are removing any particles the wire might
picked up from being placed on surfaces. If this wasn’t carried out each time, then the nichrome
wire could give off a different colour than expected and incorrect results would have been received.
…………………………………………………………………………………………………………………………………………………….
Thank you for previewing the example, feel free to buy the singular task, or the Unit 4 bundle xxx
M1 – Explain how accuracy may be ensured in the techniques used
For the quantitative and qualitative tests carried out, accurate techniques were necessary as without
them, incorrect results would have been obtained. In each test carried out special equipment was
used as it enabled not only the techniques to be smooth and precise but also allowed the results to
be as close to accurate as possible.
In the qualitative test for starch, a spotting tile was used over test tubes for two reasons. One being
that the spotting tiles white base meant that any colour change could visually be seen against the
white background where as a test tube is clear and so human error could have been made. The
second reason being that all the different foods being tested could fit onto one spotting tile instead
of using 9 different test tubes. This meant less washing up was needed to be done but also meant
that the experiment was relatively safer as no glass was available to be broken.
In the qualitative test for lipids not only was the test tube shaken instead of waiting for fat droplets
to occur, but filter paper was used for solid foods. This overall meant less test tubes were being used
and regarding solid foods, a more accurate result was given. However, errors that occurred or could
occur with the use of spotting tiles is contamination. Due to the wells being so shallow, when
dropping each piece of food into their own well, for example the Tropicana juice, this food could
have easily splashed into another well causing contamination of that piece of food and possibly
giving incorrect results. Another way contamination could have occurred is by people getting mixed
up with the pipettes. Pipettes should only be used for one type of food as if one type of food was
picked up and then another, then the second piece of food and other pieces thereafter will be
contaminated with the ones before it automatically causing negative results.
In the qualitative test for cations we held the nichrome wire in the flame before testing each
unknown compound. This is because by doing this we are removing any particles the wire might
picked up from being placed on surfaces. If this wasn’t carried out each time, then the nichrome
wire could give off a different colour than expected and incorrect results would have been received.
…………………………………………………………………………………………………………………………………………………….
Thank you for previewing the example, feel free to buy the singular task, or the Unit 4 bundle xxx
