Given below are some questions for class 9 Science :
Question 1. (a) Which method will you use to separate : (i) components of air (ii) acetone and water? Explain each.
(b) What is the difference in the apparatus used for distillation and fractional distillation?
Answers
Answer:
ch5B
Q10
find
value of c
If 1/a-1/b=1/c+1/d
when a=1/2,b=1/4 and d=- 1/5
★ANswer :
a) Which method will you use to separate : (i) components of air (ii) acetone and water? Explain each.
➳ (i) Separation of constituents of air by fractional distillation:
Air consists mainly of nitrogen and oxygen. Carbon dioxide and other gases are also present in trace amounts. To separate these different gases first we need to liquify the air. When the air is compressed and cooled down, at 0°C, water present in air freezes to ice. On further cooling, carbon dioxide separated as dry ice at about -78°C. on further cooling under pressure, air gets liquefied at -200°C. After this, through fractional distillation each gas can be separated on the basis of their boiling points. The gas having lower boiling point will be obtained first and the gas having highest boiling points will be obtained at last.
Nitrogen has a boiling point of -196°C while oxygen has -183°C. The nitrogen gas will start to escape through the outlet and it is collected. The liquid oxygen will be collected in the fractionating column.
(ii) Separation of acetone and water:
It can be done by simple distillation method. In this method, the components of mixture are separated on the basis of difference in boiling points of constituent liquids. First, the lower boiling point liquid will start boiling and its vapours can be collected and condensed to obtain the liquid. In this case acetone will come out first and left over will be water only.
(b) What is the difference in the apparatus used for distillation and fractional distillation?
➳ Fractional distillation uses a complex apparatus with a fractionating column which is long tube packed with metal wire, metal ribbon or glass beads that give extra condensing surfaces, allowing the liquid to vaporize and condense at every minute change reduce in temperature.
Simple Distillation includes a simple apparatus with a flask to contain the mixture, a condenser and a flask to collect purified components.
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