GETTING ON WITH SCIENCE IN THE LAB 2n ESO. Mass measures

	Science Department     2on ESO		MARK
MASS MEASURES
NAME:		Group:	Date:

OBJECTIVES:

• Measuring the mass of different substances.

• Handling the balance.

INTRODUCTION:

The mass is the amount of matter that something has.  The most important units are the gram (g) and kilogram (kg).

The instrument for measuring the mass is the balance. There are different types: 

       

Before using a device to measure we need to know some concepts: sensitivity, precision and accuracy.

• Sensitivity: determines the minimum measuring a magnitude that can make the device.

• Precision: A balance is precised when  the measures taken are always the same.

• Accuracy: approximation between the actual value and measured.

MATERIAL:

·         A beam balance

·         A top-loading balance

·         A pencil

·         A rubber

·         A steal ball

·         30 cm3 of water (1 ml = 1 cm3)

PROCEDURE:

With the top-loading balance:

Turn it on and wait for 0.

Measure the mass of the container in which you  will put the substance. Press the button "tare". Now only the substance in the container will be weighed.

Observe and write down  the value of weight.

Repeat the same procedure three times.

Do the same for each substance.

With the beam balance:

Put the thing in a plate and the different weighs on the other until you arrive at an equilibrium

Observe and write down  the value of weight.

Repeat the same procedure three times.

Do the same for each substance.

OBSERVATIONS

Write down the result in the table below:

	Mass  (top-loading balance)	Average (g)	Mass(beam balance)	Average (g)
Rubber 1
Rubber 2
Rubber 3
Pencil 1
Pencil 2
Pencil 3
Steal ball 1
Steal ball 2
Steal ball 3
Water 1
Water 2
Water 3

CONCLUSIONS:

a) How sensitive are the balances that you used

b) With  the results given, do you think  that the measures that you made are accurate

c) Which  balance do you think is more accurate?

  

SELF-EVALUATION:

Did you like the practise?  YES/NO

Did you learn new things? YES/NO

Do you think you have been working well? YES/NO

Did you work well with your group?