ENV 107L
Introduction to Environmental Science Lab
Class 5
Demonstration of water sample analysis and
water conservation
Outline
DO, pH, EC, temperature etc. measurement will
be demonstrated in the Lab using different
scientific instruments.
Lectures/video presentation on – Techniques of
water conservation at home.
2
Water Quality Parameters
– Physical
• Suspended solid (SS), color, taste, smell, temp.
– Chemical
• Dissolved Oxygen (DO)
• Biochemical Oxygen Demand (BOD)
• Chemical Oxygen Demand (COD)
• pH
• Electrical Conductivity (EC)
• Total Dissolved Solids (TDS)
– Biological
• Bacteria, virus, protozoa, helminthes.
3
Relationship between Dissolved Oxygen (DO) and Temperature
Temperature of water influences the amount of DO present
Less oxygen dissolves in warm water than cold water
Figure: Relationship between Dissolved Oxygen (DO) and temperature
4
Measuring Dissolved Oxygen (DO)
Three methods available for measuring dissolved oxygen concentrations
5
pH
• pH is a measure of the relative amount of free hydrogen and hydroxyl
ions in the water
• pH scale ranges from 0 to 14, with 7 being neutral.
• pHs of less than 7 indicate acidity, where as a pH of greater than 7
indicates a base.
6
pHMeasuring
of Water
pH
7
Electrical Conductivity
Conductivity is an ability of materials (solutions, metals or
gases) to pass an electric current.
An electrical conductivity meter (EC meter) measures the
electrical conductivity in a solution.
Bench-top conductivity
Digital electrical conductivity
8
Lab report -3
Include a cover page.
Table 1:
Sample
pH
Tap water
7.1
Sulfuric acid
2.0
NaOH solution
13.1
Drinking water
6.9
Liquid Antacid
11.4
Liquid soap
8.2
Vinegar
4.5
Tomato Juice
5.4
basic, acidic or neutral
Question 1: Give a title of the above table. Fill in the information
(identify if the solutions are basic, acidic or neutral).
9
Lab report -3 (contd…)
Table 2: Measurement the pH of different solutions.
Sl.
No.
1.
Samples
pH
NSU Drinking Water
?
2.
NSU Tap Water
?
3.
Juice
?
4.
Coca Cola
?
5.
Liquid Antacid
?
6.
Liquid Soap
?
Question 2: Prepare a graph to demonstrate the pH value of
different samples (that we calculated in the class).
10
Lab report - 3 (contd…)
Question 3: Prepare a graph from the following data given in the
table to show the relationship between temperature and DO.
Table 3: Relation between temperature of water (0C) and amount
of DO (mg/L).
Temperature of water (0C)
Amount of DO (mg/L)
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Question 4: Prepare Lab report based on the following
results and provide comments.
Sample
pH
DO
(mg/L)
EC
(μS/cm)
NSU tap water
Collected water sample
The results of all the analyses will be shared among the
students and the reasons for variations in water quality
(deviation from the standard range) and possible solutions will
be discussed.
12
Water Conservation
• Water conservation: careful use and protection of
water resources
• Involves both the quantity of water used and its
quality
• Conservation is an important component of
sustainable water use
Some common techniques of water conservation at
home:
https://www.youtube.com/watch?v=d5RehiMZQmc
https://www.youtube.com/watch?v=iLLYX3RbtPQ
13
Lab report - 2 (contd…)
Question 5: Briefly discuss any four water conservation techniques (that
will help to reduce water wastage and improve quality) that can be applied
at home.
14
Thanks for your kind attention
Questions
?
See you next class……
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