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Multi Beam Balance

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Here are the steps for using a multi-beam balance properly:

• Adjust all riders, so that each reads zero.

• Then check to make sure that the pointer, or beam, swings to "zero" on the center mark.

• If the pointer does not read correctly, then use the "adjustment screw" to obtain the zero reading.

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Using a Multi-Beam Balance• Warning: do not place any chemicals onto the

balance pan or platform. – All chemicals, solutions, or compounds should be

placed into a beaker or other container first

• After you place the sample onto the pan or platform, move the largest rider across the beam until the pointer drops. – Then move this rider back once.

• Follow this same procedure for the rest of the smaller riders, until the pointer swings to the zero mark.

• To record the mass, add the masses shown by each rider. (Note: masses are in grams)

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Answer: 165.32g

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Practice Time

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Electronic Balance

Accurate to .01 grams

Usually used to weigh solids

Have 2 different kinds

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Analytical Balance

Accurate to 0.001 grams

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Using a Digital Balance

1. Sometimes when nothing is on the balance pan, the mass display will show a non-zero reading.

2. Taring is used to set the mass display to zero.

3. Once the balance has been tared, the mass of any object set on the balance pan will be displayed on the digital readout.

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Accuracy of Coins

= of a measurement is how close that measurement is to the true or “exact” value

EX: Standard weight = 5.00g

4.98g more accurate than 5.12 g

Accuracy is also subject to the reliability of the measuring instrument.

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Determining the % Accuracy of a Balance

To calculate the % accuracy of the balance you are using

% Accuracy = experimental value X 100reference or standard value

The larger this value, the greater the degree of accuracy.

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Double Pan Balance – can be used to determine the mass of an

object by comparing its mass to the masses with a known weights.

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Will use these in lab today to compare the mass values of sets of washers.