Mass Reading (P)

Question 1

What is mass?

Answer 1

It is the fundamental measure of the amount of matter in an object

Question 2

What is weight?

Answer 2

It is the force of gravity on an object

Question 3

What is weighing?

Answer 3

It is the determination of mass of an object using a balance

Question 4

What is the formula to compute for weight?

Answer 4

Weight = Mass x Gravity

Question 5

What are the differences between mass and weight?

Answer 5

Mass:

1) It is how much matter an object contains
2) It is constant for a body and does not change with location
3) Kilogram is the unit of mass

Weight:

1) It is the force exerted on a mass by gravity
2) It is not constant. It changes from place to place
3) Newton is the unit of weight

Question 6

What are the general rules in weighing?

Answer 6

1) Do not handle objects with bare hands.
2) Never weigh chemicals directly on the balance pan; use a glass container or weighing paper.
3) Never add chemicals to a container or piece of weighing paper while it is on the balance.
4) Do not weigh hot or cold objects.
5) Check to be sure that the balance is level.
6) Keep the weighing balance clean

Question 7

What are the different parts of triple beam balance?

Answer 7

1) Stainless Steel Weighing Pan or Plate
2) Poise
3) Notched Beams
4) Trig loop assembly
5) Zero adjust knob
6) Attachment Weight Pivot
7) Vane and Magnetic Dampener inside Trig loop
8) Stainless Steel Bearing Covers (self-aligning bearings inside)

Question 8

How to use the triple beam balance?

Answer 8

1. Make sure that the balance is on level and the scale is on zero mark.
2. Place the container on the weighing pan.
3. Move the adjustment to the right until the pointer indicates the equal sway on either side of the midpoint of the balance.
4. Record the weight of the container.
5. Place the sample on the container.
6. After measuring the sample, subtract the weight of the container

Question 9

Aside from triple beam balance, what are the other 2 types of balance used in the lab?

Answer 9

1) Analytical balance

2) Digital / Top load balance

Question 10

What are the parts of the analytical balance?

Answer 10

1) Draft shield
2) Level indicator
3) Display
4) Door handle
5) Balance pan
6) Tare button
7) Power button
8) Level adjustment feet

Question 11

How to operate an analytical balance?

Answer 11

1) Insert the power supply connector.
2) Wait until the auto-test is finish and zeroes are displayed.
3) Place the empty container on the pan.
4) Press the TARE key.
5) Fill the container with the sample.
6) Record the measurement

Question 12

What are the 2 methods of weighing?

Answer 12

1) Direct weighing

2) Weighing by difference (or indirect weighing)

Question 13

What is direct weighing?

Answer 13

Means that an object is placed directly on a balance and the mass is read

Question 14

How is direct weighing done? Give an example

Answer 14

Weigh 1.50 grams Copper Sulfate:

1) The balance is zeroed with nothing on the pan
2) Copper sulfate is added on the balance pan until the balance reads at 1.50 gram

Question 15

How is weighing by difference done via method 1?

Answer 15

Method 1:

1) A clean piece of weighing paper is placed on a pan
2) Measure and this is your first reading
3) The substance to be weighed is placed on the weighing paper. This is the second reading
4) The mass of the substance is determined by subtracting the first reading from the second

Question 16

Provide an equation on how to compute the mass of substance using method 1 (of weighing by difference)

Answer 16

Mass of substance = (Mass of paper + substance) - (Mass of Paper)
1.88 g - 0.38 g = 1.50 g

Question 17

How is weighing by difference done via method 2?

Answer 17

1) A container holding the substance of interest is placed on the balance and weighed. This is the first reading.
2) The substance to be used is removed from the container and the container is weighed again. This is the second reading.
3) The mass of substance taken is determined by subtracting the second reading from the first

Question 18

Provide an equation on how to compute the mass of substance using method 2 (of weighing by difference)

Answer 18

Mass of substance removed = (Mass of container + substance) - (mass of container + substance after removal)
31.56 g - 30.06 g = 1.50 g

Question 19

What is the principle in method 3 (on weighing by difference)?

Answer 19

The principle of taring the balance

Question 20

What is method 3 (on weighing by difference)?

Answer 20

Weighing by difference is done automatically
The weight of the container is substracted from every reading
Just push the tare button

Question 21

What is the capacity and margin of error of triple beam balance?

Answer 21

Capacity: 610 - 2,610 g

Margin of Error: 0.05 g

Question 22

What is the capacity and margin of error of digital balance?

Answer 22

Capacity: 320 g
MOE: -/+ 0.05 g

Question 23

What is the capacity and margin of error of analytical balance?

Answer 23

Capacity: 200 g
MOE: -/+ 0.02g

Question 24

How to calibrate a volumetric flask?

Answer 24

1) Clean and rinse 3 volumetric flasks of appropriate size. (25, 50, 100 mL capacity)
2) Clearly label each flask.
3) Rinse the flasks 2 or 3 times with 2 mL of acetone, making sure that you cover all inside surfaces with the acetone rinses, and discard these rinses. Allow the residual acetone to evaporate
4) Place the flasks on the analytical balance.
5) Determine the mass of each flask and its stopper, and record these masses.
6) Make sure that you tare the balance before massing each flask.
7) Fill each of the flasks with distilled water to the fill line.
8) Discard the distilled water

Question 25

Is it okay to dispose water and acetone down the sink drain?

Answer 25

Yes

Question 26

What should be done to any broken glassware?

Answer 26

It is disposed in the broken glass container

Question 27

What should be done to a container containing broken glass?

Answer 27

Label the container

Question 28

What are the steps in handwashing?

Answer 28

1) Remove jewelries then wet your hands.
2) Apply soap. (quarter-sized portion of soap)
3) Rub palms together to create rich lather for 5 seconds.
4) Rub backs of the palm. Use right palm to massage back of your left hand. Switch hands after 3 seconds.
5) Interlace fingers, clean the underside of fingers by rubbing them along the knuckles.
6) Scrub thumbs. Clasp right hand over the left thumb and rotate for 3 seconds. Repeat on the right thumb.
7) Rub palms with fingertips. Rotate right hand fingers clockwise and then counterclockwise on the left palm. Switch hands for 3 seconds.
8) Rinse. Wash soap away until water turns clear and there are no suds present. Turn the faucet using elbow or paper towel.
9) Dry using a paper towel or hand dryer

Question 29

What is the proper way of donning PPE?

Answer 29

1) Do proper handwashing / disinfect hands
2) Don lab coat / gown
3) Don mask
4) Don safety goggles / glasses; face shield can also be used (safety glasses + face shield)
5) Don gloves

Question 30

What is the proper way of doffing PPE?

Answer 30

1) Doff gloves
2) Doff lab coat / gown
3) Doff safety goggles / glasses; doff also face shield if present
4) Doff mask
5) Do proper handwashing / disinfect hands