Measuring Mass Using a Centigram and an Electronic Balance - Lab Report Example

The experiment is divided into four parts: Part 1: Measuring mass directly using a centigram balance 1) Select centigram balance from the equipment selection in the toolbar. 2) Right-click on the balance and from chemicals select copper slug changing the quantity from 0 to 1.3) Record the reading obtained in grams measuring mass by weight difference method using a centigram balance1) Add a centigram balance to the workspace2) Add a 100mL from equipment selection using the same method and record its mass3) Next add the copper slug from the previous measurement to the beaker.

To do this, drag the beaker by left-clicking on it below the first balance which contains the copper slug. Now right-click on the first balance and select pour/decant. The copper slug will drop into the beaker. To measure the total mass of the beaker and the copper slug drag them to the second balance. Record the reading4) Obtain the mass of the copper slug by subtracting the mass of the beaker from the total mass of the beaker and the slug. Part 2Measuring mass directly using an Electronic Balance1) Left-click on the balance with slug, select transfer to a new container, and click on an electronic balance.2) Record the reading measuring by Weight Difference method using an Electronic Balance1) Left-click on the balance with the beaker and slug from Part 1 of the experiment and use the method given above to transfer it to an Electronic Balance.2) Record the reading3) Remove the beaker from the balance and empty it by right-clicking and selecting Empty.4) Place the beaker on the balance again and record the reading.5) Subtract the reading obtained in step 4 from the reading obtained in step 2 to get the mass of the copper slug.

Part 3 Calculating the Average Mass of a copper slug using an Electronic Balance1) Obtain an Electronic Balance using the method described earlier2) Add a copper slug using the method described earlier and record the mass3) Add a second copper slug and record the mass4) Add a third copper slug and record the mass5) Add a fourth copper slug and record the mass6) Add a fifth copper slug and record the mass7) Divide by 5 the reading obtained in step 6 to obtain the average mass of a copper slugPart 4Determining the Mass of Unknown Weights1) Obtain a Centigram Balance2) Add beaker and record the reading3) To the beaker adds Unknown Weight 1 and record the total mass of both4) Subtract the reading obtained in step 2 from the reading obtained in step 3 to get the mass of Unknown Weight 15) Repeat the same steps for Unknown Weight 2Observations and ResultsWeighing DirectlyInstrumentMass recorded/centigram Balance2.

3Electronic Balance2.999Weighing by DifferenceInstrumentMass of 100ml beakerMass of beaker+slugMass of slug:(mass of beaker+slug)-(mass of beaker)Centigram49.152.12.2Electronic Balance50.00052.9892.989Average Mass of a Copper Slug with an Electronic Balance: Mass of 1 copper slug/glass of 2 copper slugs/glass of 3 copper slugs/glass of 4 copper slugs/glass of 5 copper slugs/average mass of a copper slug/g2.9795.9878.95311.93614.9022.980Determining the Mass of Unknown Weights with a CentigramMass of 100ml beakerMass of beaker+weight/glass of weight:(mass of beaker+weight)-(mass of beaker)Unknown Weight 149.157.38.

2Unknown Weight 249.158.29.1Discussion: The Centigram Balance, which gives a reading of 2.3 on weighing the copper slug directly, has a sensitivity of 0.1 grams, whereas the Electronic Balance which gives a reading of 2.999 for the same slug has a much higher sensitivity of 0.001g. It is important to use the same slug for both instruments to make sure that any disparity in the readings is due to the instrument being used and not because of a difference in the mass of the copper slug being measured.

The Electronic Balance has a higher accuracy. This is further proved by the value obtained for the average mass of a copper slug using an Electronic Balance. This value, 2.980, is very close to the reading of 2.989 which was obtained when a copper slug was measured on the Electronic Balance using the weight difference method. The Electronic Balance, due to its high sensitivity and accuracy is more reliable for the measurement of small masses. The Centigram on the other hand has a much lower accuracy and sensitivity and is thus unsuitable for small masses.