F2 IS EXP 02 Answers

1st Term EXP 02 Submission date：_____________ Name：______________________ Class & no.：2 _________(     )

Experiment 7.1C: Comparing比較 the oxygen and

carbon dioxide content of breathed air未經呼吸的空氣

and unbreathed air呼出的空氣 (P.9-11)

Objective: To compare the oxygen and carbon dioxide content of breathed / unbreathed air

and unbreathed / breathed air.

Results結果:

B. Comparing the oxygen content

	Breathed air	Unbreathed air
Time taken for burning splint to go out (s)	(shorter time)	(longer time)

C. Comparing the carbon dioxide content

	Breathed air	Unbreathed air
Colour of hydrogencarbonate indicator after shaking	yellow	red

Discussion結論:

(a)    Which one contains more oxygen, breathed air or unbreathed air? unbreathed air

(b)   Explain how you get your answer in (a)?

The splint burns for a longer time in the jar which contains more oxygen. (OR other reasonable answers)

Conclusion結論:

Ø   Breathed air contains less oxygen than unbreathed air.

Ø   Breathed air contains more carbon dioxide than unbreathed air

Experiment 7.1D: Compare the temperature of breathed air and unbreathed air

Objective:      To compare the temperature of breathed air and unbreathed air.

Results:

	Breathed air	Unbreathed air
Temperature (oC)	(higher)	(lower)

Conclusion:

Ø   The temperature of breathed air is higher than that of unbreathed air.

Experiment 7.1E: Compare the water vapour content (水蒸汽) of breathed air and unbreathed air

Objective:      To compare the water vapour content of breathed air and unbreathed air.

Results:

	Under breathing	Without breathing沒有呼吸
Colour change of the cobalt chloride paper	Colour changes from blue to pink	No colour change

Discussion結論:

What can you see when you breathe on the mirror? Small droplets / moisture / a misty appearance

Conclusion:

Ø   Breathed air contains more water vapour than unbreathed air.