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					                            MEASURING MASS USING
                            A TRIPLE BEAM BALANCE




Carrying the Balance

      1. Be sure all riders are back to the zero point.
      2. Place one hand under the balance and the other hand on the support (arm) to
      carry the balance.

Using the Balance

      1. Zero the balance before you determine the mass of any substance.
           a) Slide all of the riders back to the zero point.
           b) Check to see that the pointer swings freely along the scale.
           c) Use the adjustment screw to obtain an equal swing of the beams, if
      necessary. You do not have to wait for the pointer to stop at the zero point. The
      beam should swing an equal distance above and below the zero point.
       You must repeat this procedure to "zero" the balance every time you use it.

   2. Measuring Mass

   Move the 100 gram slider along the beam to the right until the pointer drops below the fixed
   mark. The notched position immediately to the left of this point indicates the number of
   hundreds of grams.

   Now move the 10 gram slider along the beam to the right until the pointer drops below the
   fixed mark. The notched position immediately to the left of this point indicates the number of
   tens of grams.
The beam in front is not notched; the slider can move anywhere along the beam. The
boldface numbers on this beam are grams and the tick marks between the boldface numbers
indicate tenths of grams.

To find the mass of the object on the pan, simple add the numbers from the three beams.

The balance must be at room temperature to be used accurately. Chemicals and powders
should not be placed directly on the pan. The chemicals could corrode or damage the pan
altering the measurements. All powders or chemicals should be placed in a beaker or
appropriate glass ware when being measured. The mass of a beaker must be measured before
placing the chemical inside the beaker so that it can be subtracted from the total mass in
order to obtain only the mass of the chemical.

Background Questions
1. Describe what to do with the riders of a balance scale when you want to measure
the mass of an object. Explain why this is necessary.




2. When determining the mass of an object on a balance, which rider do you move
first?


3. For an accurate measurement, an object should be at what temperature? Why?




4. Explain the importance of the following procedures:
(a) Chemicals and powders must not be placed directly on the balance.




(b) You must measure the mass of a beaker before measuring the mass of a
chemical or powder inside the beaker.
6. Label the balance with the following terms: pan, pointer, rider, beam, adjustment
screw.
7. List the parts of a balance below. Describe the function of each part.

    Parts of a Balance                             Function of Part
   TRY MEASURING THE MASS OF AN OBJECT USING THE TRIPLE
   BEAM BALANCE. WRITE THE NAME OF THE OBJECT AND ITS
   MASS BELOW.



   _________________________________________________




1. Measure the mass of 5 pennies. Estimate the mass before using the
   balance.

       a. What is your estimate?




       b. What is the mass of the pennies?




2. a. Estimate the mass of 10 pennies




   b. measure the mass of 10 pennies




3. Measure the mass of 100mL of water. Explain how you will find the mass of the
   water. All calculations should be shown below.

       a. Estimate the mass of the water




       b. Explain how you will find the mass of the water. What materials will you
          need. Ask your teacher for any materials needed.
         c. What is the mass of the empty beaker?




         d. What is the mass of the beaker and the water?




         e. What is the mass of 100mL of water? Show all calculations




  4. What is greatest mass the triple beam balance can measure? Show your calculations
     below




BE SURE TO ZERO YOUR SCALE WHEN PUTTING AWAY. COLLECT THE
HOMEWORK SHEET WHEN FINISHED

				
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posted:8/8/2012
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