Ch.2.3 Flashcards
Water is ___________ for life on Earth.
Essential.
Humans can survive up to several weeks without food. However, without water, one will likely __________ within a ___________ ___________.
die, few days.
Only some forms of life contain water.
True/ false?
False.
Give 5 ways of how we use water in many ways in daily life.
Washing, cooking, taking a shower, crop irrigation, creating paper and clothes
In some parts of the world, people do not have tap water. They use natural water directly from __________, _________, _______ or _______.
Streams, rivers, ponds, wells.
Natural water contains many kinds of impurities:
* Some of them such as leaves and sand are \_\_\_\_\_\_\_\_\_\_\_ in water * Some impurities are \_\_\_\_\_\_\_\_\_\_\_ in water, eg salt * Natural water also contain \_\_\_\_\_\_\_\_\_\_\_\_\_\_
Insoluble, soluble, microorganisms
Microorganisms are too small to see with the naked eye but we can observe them with the help of a ________________.
Microscope.
__________ and _________ are two microorganisms often found in natural water.
Amoeba, E. coli.
Some microorganisms are harmful to us. They may cause _____________ diseases and other diseases such as ______________ and ____________.
Diarrhoeal, typhoid, chlolera
E. coli in water or food often cause ___________ diseases.
Diarrhoeal.
What are the three methods of water purification?
Sedimentation, distillation and filtration.
Sedimentation can remove __________________.
Large insoluble impurities.
During sedimentation, the large and heavy insoluble impurities sink to the _____________ of the container and form a layer of ___________.
Bottom, sediment.
After sedimentation, the water above the sediment becomes ___________. However, some _____ ________ _____ are still suspended in it.
Clearer, small insoluble impurities.
We can remove __________ _________ __________ and __________ __________ _________ in water by filtration.
Small insoluble impurities, large insoluble impurities.
___________ ___________ and _________ __________ are commonly used filters in the laboratory.
Filter columns, filter papers.
Filter paper has many ________ ___________.
Tiny pores.
The small insoluble impurities are ___________ than the pores of a filter paper. Thus, these impurities cannot pass through the pores and are ___________ by the filter paper.
Larger, trapped.
The small insoluble impurities trapped in the pores of a filter paper are called ___________.
Residue.
The liquid that passes through the filter paper is called _________.
Filtrate.
On the other hand, ____________ and _____________ __________ (eg salt) are much smaller than the pores of the filter paper. Hence, they pass through the filter paper.
Microorganisms, soluble impurities.
Filtration can be used to remove _________ and _________________________ from water.
Large, small insoluble impurities.
Filtration is used in some ___________ _________ ___________ for removing impurities from tap water.
household water filters.
In distillation, water _________ and changes to ___________.
Boils, steam.
