distinction grade assignment for unit 2a chemistry 'concentrate on keeping up standards' in year 1 of applied science / forensic and criminal investigation btec
Concentrate On Keeping Up Your Standards - First Assignment
Calibration of Glassware
Aim
Our aim was to assess the accuracy of glassware used in our lab by measuring the
mass of 25cm³ of water. The known density of water is 1g/cm3, so it should therefore
be exactly 25g in mass for our glassware to be considered accurate.
As we’re dealing with glassware, it’s important to be conscious that we’re handling
them carefully and to know where the dustpan and brush and dedicated glass bin
are in the classroom.
Method
1 Zero a 2d.p balance.
2 Place a clean and dry 100 cm3 beaker on the balance and record its mass.
3 Deliver 25 cm3 of distilled water from a pipette to the beaker and record the new mass.
4 Calculate the mass of the water delivered.
5 Discard the water and dry the beaker thoroughly with the paper towel provided.
6 Repeat steps 1–5 for 25 cm3 delivered (at step 3) from a burette, from a 100 cm3 beaker with
graduations and from a 25 cm3 measuring cylinder.
Results
Pipette Burette 100 cm3 25 cm3
beaker measuring
cylinder
Mass of beaker 69.85g 71.89g 68.38g 69.54g
plus 25 cm3
water
Mass of empty 44.69g 44.69g 44.69g 44.69g
beaker
Mass of 25 cm3 25.16 27.20 23.69 24.85
water
% error of this 0.64 8.80 -5.24 -0.60
equip.
Analysis
From the results table we can see that the two types of glassware with the smallest
percentage error were the pipette and measuring cylinder, making them the most
accurate used in this experiment. This is because the 25cm3 line is very clearly
marked on both of them and it’s fairly easy to transfer the water from the glassware
to the beaker. The burette is quite difficult at first to stop immediately and it can be
, easy to make a mistake and run too much of the solution inside of it into the beaker
below, which is why it was the least accurate piece of glassware in our results. As
well as the burette, the 100cm3 beaker was not completely accurate as the 25cm3
line may not have been marked as clearly, so we would have had to determine for
ourselves whereabouts it would be between the 0cm3 marker and the 50cm3 marker;
additionally, there may have been some water left in either beaker which wouldn’t
have been accounted for and which could’ve caused the glassware to appear less
accurate. To improve this experiment further we could have calibrated the glassware
using 4d.p balances to give us more accurate results, but the difference would have
been so small and wouldn’t be necessary for the experiments that we carry out,
therefore it wasn’t overly needed.
Calibration of Balances
Aim
The aim for this test was to check that the balances that we use in our lab are within
tolerance by checking how they register known masses of 1g and 10g and how
accurate the readings are for them. It’s important that we are able to trust that our
equipment provides correct data to ensure the validity of our experiments.
Method
1. On a 2 decimal place balance, weigh a 1g mass by itself and record the
results
2. On this same balance, weigh a 10g mass by itself and record the results
3. For the 2 d.p balance to be within tolerance, the reading for the 1g mass must
be between 0.99g and 1.01g
4. The 10g mass must read between 9.98g and 10.02g
5. Repeat these steps for a 4d.p balance and record both results
6. The reading for the 1g mass must be between 0.9999g and 1.0001g for the 4
d.p analytical balance to be within tolerance.
7. The reading for the 10g mass must be between 9.9998g and 10.0002g
Results
Date Balance Mass of 1 Within Mass of Within
type (dp) g/g tolerance? 10 g/g tolerance?
23/1 2 1.00 yes 10.02 yes
23/1 4 1.0036 no 9.9989 no
Analysis
Through our testing we found that although using 4 d.p analytical balances produced
more accurate data, they were not within tolerance and therefore the readings of
them may not be as accurate as we would hope them to be. On the other hand, the 2
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller kitmustdie. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £8.79. You're not tied to anything after your purchase.
