Thermometer

1. A thermometer is an instrument to measure temperature.

2. Units for temperature are : a) degrees  Celsius  ( °C )
                                                        b) degrees Fahrenheit  ( °F )


3. A thermometer consists of a narrow glass tube with a bulb at the tip.

Thermometer

4. The bulb is filled with mercury ( silver ) or alcohol ( red ).


5. Mercury will expand when heated.

6. The volume of mercury increases as the mercury expands.

7. This will cause the mercury level in the tube to rise.

8. Mercury will contract when cooled.

9. The volume of mercury decreases as the mercury contracts.

10.This will cause the mercury level in the tube to fall.

11.The rise and fall of mercury level shows the temperature reading of an object.

What food is acidic? What food is alkaline?

Aim: To investigate the properties of acidic, alkaline and neutral food.

Procedure: 1.Prepare food samples as below.

water

noodles

vitagen

bitter gourd

orange

                  2.Taste each of food samples, then record the taste of the food.

                  3.Use wet blue and red litmus paper to test the food samples.

                  4.Record the observation into table 1.


Observation:

Food sample	Taste	Red litmus paper	Blue litmus paper
Bitter gourd	Bitter	Red è blue	Blue è blue
Orange	Sour	Red è red	Blue è red
Noodles	Bitter	Red è blue	Blue è blue
Water	No taste	Red è red	Blue è blue
Vitagen	Sour	Red è red	Blue è red

                                                                        Table 1

Conclusion: 1. Acidic food tastes sour, changes blue litmus paper to red.


                    2. Alkaline food tastes bitter, changes the red litmus paper to blue.


                    3. Neutral food does not taste either sour or bitter, cannot change the colour of blue or red
                        litmus paper.

Chemical Properties Of Matter

ACIDIC, ALKALINE AND NEUTRAL

1. Different substances have different chemical properties.
2. Substances can be classified as having these properties:

•  acidic
• alkaline
• neutral

     3.  A substance can be tested to see if it is acidic, alkaline or neutral using a litmus paper.

   

Acidic Substances

1. An acidic substance has a sour taste.
2. It change blue litmus paper to red.
3. If the acidic substance is tested with a red litmus paper, no colour change will be seen.
4. A strong acidic is corrosive and can burn the skin.

orange

          



grapes 

pineapple

lemon

mango

apple cider vinegar

                  Figure 1: Acidic substances

Alkaline Substances

1. Alkaline substances taste bitter and feel 'soapy' to touch.
2. It change red litmus paper to blue.
3. If the alkaline substance is tested with a blue litmus paper, no colour change will be seen.
4. A strong alkaline is corrosive and can burn the skin.

detergent powder

bitter gourd

soap

body shampoo

toothpaste

Figure 2: Alkaline substances  

Neutral Substances

1. A neutral substance does not have an acidic or alkaline properties.
2. It will not change the colour of blue or red litmus paper.
3. If an acidic substance is mixed with an alkaline substance, a neutral substance is formed.

cocking oil

mineral water

sugar

rice

honey

bread

           

                                            

Figure 3: Neutral substances       

Experiment: Pendulum for measuring time

• Question: Are the swings of a pendulum uniform?
• Aim: To study the relationship between the length of the string and the period of the pendulum to swing 20 times.
• Apparatus: String, stopwatch, nut, scissors and retort stand.

Procedure:

1. Tie a 10 cm string onto the nut to become a pendulum.
2. Swing the pendulum and record the period for the pendulum to swing 20 times.
3. Repeat procedure 1 and 2 with 15 cm, 20 cm and 25 cm strings.
4. Record the observation.

Observation:

The length of the string (cm)                      10           15          20          25

The period for the pendulum
to swing 20 times (second)                         20           25          30          35


Discussion:

1. What is the trend of change for the period of the pendulum to make 20 swings?

          Increase uniformly

     2.  State two variables in the investigation.

          The length of the string used and the period of the pendulum to make 20 swings.

Conclusion: The longer the string, the longer the period for the pendulum to swing 20 times.

Formation Of Clouds And Rain

• The Sun heats up the surface of the Earth.
• Water from land, seas, lakes and rivers evaporates to form water vapour in the air.
• Water vapour rises, meets the cool air above and condenses.
• Water droplets are formed.
• These water droplets come together to form clouds.
• When more water vapour condenses, the water droplets join to form bigger and heavier clouds.
• These water droplets will fall onto Earth as rain.
• Rain will return to land, rivers, lakes and seas. 
• This process repeats and is known as the water cycle.
• The process ensures that the total volume of water on Earth is constant.