MEASUREMENT OF MASS AND VOLUME

OBJECTIVES: AT THE END OF THE DISCUSSION, THE STUDENTS/OUR CLASSMATES SHOULD BE FAMILIAR WITH THE DIFFERENT LABORATORY EQUIPMENT COMMONLY USED ON MEASURING MASS AND VOLUME

MEASUREMENT OF MASS

TRIPLE BEAM BALANCE

WHAT IS TRIPLE BEAM BALANCE?

IT MEASURES THE MASS AND NOT THE WEIGHT OF AN OBJECT.

IT IS ONE WEIGHING DEVICE, WHICH ALLOW THE USER TO ACCURATELY GAUGE THE MASS OF AN OBJECT IN GRAMS.

IT CAN PROVIDE HIGHER ACCURACY THAN A SPRING-BASED MEASURING SCALE, AND HAS AN ERROR MARGIN FOR ONLY 0.05 gm. THEREFORE, IT IS PRIMARILY USED AS A LABORATORY APPARATUS.

PARTS OF A TRIPLE BEAM BALANCE:

BASE AND PANTHE SOLID METAL PLATFORM WHICH SUPPORTS THE REST OF THE PARTS OF THE TRIPLE BEAM BALANCE IS KNOWN AS THE BASE.THE PAN IS LOCATED ON ONE SIDE OF THE APPARATUS AND RESTS ON TOP OF THE BASE. IT IS WHERE THE OBJECT TO BE WEIGHED IS PLACED.

ADJUSTMENT KNOB THE ADJUSTMENT KNOB IS PRESENT ON THE LEFT HAND SIDE OF THE APPARATUS, BENEATH THE PAN. IT CAN BE TURNED TO ATTAIN GREATER ACCURACY WHILE MEASURING THE WEIGHT OF AN OBJECT USING THE TRIPLE BEAM BALANCE.

POINTERTHE POINTER IS PRESENT ON THE RIGHT HAND SIDE OF THE TRIPLE BEAM BALANCE. BY DEFAULT, IT POINTS TO ZERO ON A LABELED SCALE. TOGETHER THE POINTER AND THE SCALE ARE USED TO ASCERTAIN WHEN THE BEAMS ARE AT THEIR RESTING POSITIION, AND TO DETERMINE WHEN THE CORRECT MASS OF AN OBJECT HAS BEEN FOUND.

TRIPLE BEAMS AND RIDERSAS THE NAME OF THIS APPARATUS IMPLIES, THE TRIPLE BEAM BALANCE COMPRISES THREE BEAMS WHICH ARE INDIVIDUALLY USED TO DETERMINE THE MASS OF AN OBJECT. EACH OF THESE THREE BEAMS HAS A WEIGHTED RIDER ON IT, WHICH THE USER CAN SLIDE ALONG THE LENGTH OF THE BEAM TO DETERMINE THE OBJECT’S MASS.

Measuring mass directly1. KEEPING THE PAN EMPTY, MOVE ALL THREE RIDERS ON THREE BEAMS TO THEIR LEFTMOST POSITIONS. CHECK THE POINTER AND SCALE TO ENSURE THAT IT READS ZERO. IF IT DOESN’T THE CALIBRATE THE SCALE BY TURNING THE ADJUSTMENT KNOB UNTIL A ZERO READING IS OBTAINED.2. AFTER CALIBRATON, PLACE THE OBJECT TO BE MEASURED ON THE CENTER OF THE PAN. THE POINTER WILL MOVE AWAY FROM THE ZERO READING.

3. SLIDE THE 100 gm RIDER TO THE LEFT SLOWLY FROM NOTCH TO NOTCH, UNTIL THE POINTERDROPS BELOW ZERO MARK. AT THIS POINTMOVE THE RIDER BACK A NOTCH.4. NOW MOVE THE 10 gm RIDER FROM NOTCH TO NOTCH IN A SIMILAR MANNER AS YOU DID WITH THE 100 gm NOTCH UNTIL THE POINTER DROPS BELOW ZERO AT WHICH POINT, YOU MUST MOVE IT BACK A NOTCH.5. LASTLY, MOVE THE 1 gm RIDER SLOWLY ON ITS BEAM UNTIL THE POINTER ALIGNS AT ZERO.

6. TAKE THE TOTAL OF ALL THE THREE NUMBERS INDICATED BY THE POSITIONS OF THREE RIDERS TO GET THE MASS OF THE OBJECT ON THE PAN.

FINDING MASS BY DIFFERENCE1. KEEPING THE PAN EMPTY, MOVE ALL THREE RIDERS ON THREE BEAMS TO THEIR LEFTMOST POSITIONS. CHECK THE POINTER AND SCALE TO ENSURE THAT IT READS ZERO. IF IT DOESN’T THE CALIBRATE THE SCALE BY TURNING THE ADJUSTMENT KNOB UNTIL A ZERO READING IS OBTAINED.2. YOU MUST FIRST MEASURE THE MASS OF THE EMPTY CONTAINER.3. THEN YOU TAKE THE MASS OF THE CONTANER WITH THE LIQUID/FLUID ON IT.

4. ADD UP THE RESULTS AND SUBTRACT IT TO THE MASS OF THE CONTAINER ALONE TO TAKE THE MASS OF THE LIQUID/FLUID ALONE.

MEASURING OUT A SUBSTANCE1. KEEPING THE PAN EMPTY, MOVE ALL THREE RIDERS ON THREE BEAMS TO THEIR LEFTMOST POSITIONS. CHECK THE POINTER AND SCALE TO ENSURE THAT IT READS ZERO. IF IT DOESN’T THE CALIBRATE THE SCALE BY TURNING THE ADJUSTMENT KNOB UNTIL A ZERO READING IS OBTAINED.2. FIND THE MASS OF THE WEIGHING PAPER3. IF YOU HAVE THE MASS OF YOUR PAPER ZEROED OUT, THEN YOU CAN ADD THE AMOUNT OF YOUR SUBSTANCE.4. ADD THE CHEMICAL/SUBSTANCE SLOWLY UNTIL THE ZERO MARKER POINTS AT ZERO.

ANY QUESTIONS?