Hard water is caused by dissolved calcium and magnesium compounds from sources like limestone and chalk rocks. It does not lather easily with soap. There are two types of hardness: temporary, caused by calcium hydrogen carbonate and removed by boiling; and permanent, caused by other compounds and not removed by boiling. Permanent hardness can be removed through distillation, adding sodium carbonate, or using ion exchangers. Hard water has advantages like taste and providing calcium, but disadvantages like requiring more soap and causing scaling. Water treatment plants filter, precipitate minerals, filter through sand, chlorinate, and sometimes fluoridate water to make it safe to drink.
An introductory presentation on corrosion and its prevention. Importance of corrosion, cost of corrosion, various forms of corrosion, and preventive methods are given.
An introductory presentation on corrosion and its prevention. Importance of corrosion, cost of corrosion, various forms of corrosion, and preventive methods are given.
14 Types of Corrosion explained in an awesome manner
Update 26 June 2019: I have enabled the Download option and now everyone can download the "Types of corrosions" PPT and reuse the slides :) I wish I have done this earlier.
Follow my blogs at https://www.geekdashboard.com/
A brief introduction to corrosion and types of corrosion, such as pitting corrosion.
Cavitations corrosion
Galvanic corrosion.
Fretting corrosion.
Crevice corrosion.
Intergranular and transgranular corrosion,
Stress corrosion
Water treatment procedure also vary depending upon its use. However, overall picture of water treatment, irrespective of end use shall be considered. An endeavor is made to comprehend the basic chemistry involved in water treatment process. The important stages involved in treatment are as follows: coagulation or flocculation; sedimentation; filtration – slow sand, rapid sand filtration; disinfection – including chlorination and ozonolysis; removal of iron and manganese; softening by lime-soda ash process or deionization method; scale and corrosion control; taste and odor removal; prophylaxiation treatment, i.e., fluoridisation; and specialized treatment for a specific purpose.
14 Types of Corrosion explained in an awesome manner
Update 26 June 2019: I have enabled the Download option and now everyone can download the "Types of corrosions" PPT and reuse the slides :) I wish I have done this earlier.
Follow my blogs at https://www.geekdashboard.com/
A brief introduction to corrosion and types of corrosion, such as pitting corrosion.
Cavitations corrosion
Galvanic corrosion.
Fretting corrosion.
Crevice corrosion.
Intergranular and transgranular corrosion,
Stress corrosion
Water treatment procedure also vary depending upon its use. However, overall picture of water treatment, irrespective of end use shall be considered. An endeavor is made to comprehend the basic chemistry involved in water treatment process. The important stages involved in treatment are as follows: coagulation or flocculation; sedimentation; filtration – slow sand, rapid sand filtration; disinfection – including chlorination and ozonolysis; removal of iron and manganese; softening by lime-soda ash process or deionization method; scale and corrosion control; taste and odor removal; prophylaxiation treatment, i.e., fluoridisation; and specialized treatment for a specific purpose.
Which salt is more soluble in water CaCO_3 vs. MgCO_3 What are tw.pdfalrahmancollection
Which salt is more soluble in water: CaCO_3 vs. MgCO_3 ? What are two major problems
associated with hard water? List two technologies for water softening. What is the pH range of
most natural waters? Name three weak bases found in natural waters. River A with a flow rate
of 16,000 m^3/d flows into a well-mixed lake with a volume of 1,000,000 m^3 throughout the
year. River B and river C leave the lake. A boat in the lake has polluted the lake with an organic
pollutant. Microbes present in the lake are capable of biodegrading this pollutant with a first-
order decay constant of 0.01 d^-1. Determine the percent removal of pollutant in river C (or the
percent decrease of the pollutant concentration in river C) after 180 days. The mineral analysis
in mg/L as ion for a water source is: Ca^2+ 100 Mg^2+ 20 HCO_3^- 200 CO_2 20 How
much lime and soda are required (in mg/L as CaCO_3) to soften the water to 100 mg/L as
CaCO_3? A water sample contains 20 mg/L of sodium hydroxide. How much manganese (II) is
soluble in this water? Determine the percent dissociation of bicarbonate in this water.
Solution
1. (a) MgCo3 is more soluble in water than CaCo3.
(b). Problems associated with hard water:
Laundering:
Clothes washed in hard water often look dingy and feel harsh and scratchy. The hardness
minerals combine with some soils to form insoluble salts, making them difficult to remove. Soil
on clothes can introduce even more hardness minerals into the wash water. Continuous
laundering in hard water can damage fibers and shorten the life of clothes by up to 40 percent.
Bathing:
Bathing with soap in hard water leaves a film of sticky soap curd on the skin. The film may
prevent removal of soil and bacteria. Soap curd interferes with the return of skin to its normal,
slightly acid condition, and may lead to irritation. Soap curd on hair may make it dull, lifeless
and difficult to manage.
Dishwashers:
When washing dishes, especially in a dishwasher, hard water may cause spotting and filming on
your crockery. The minerals from hard water are released faster when it comes into contact with
heat, causing an increase in the amount of spotting and filming that occurs. This problem is not a
health risk, but it can be a nuisance to clean and reduce the quality of your crockery.
(c)
(i) Ion Exchange : The oldest method of treating hard water, ion exchange uses a process of
removing calcium and magnesium from the water by exchanging each calcium ion for two
sodium ions.
(ii) Distillation: Distillation is a water purification process that uses a heat source to turn the
water into its gaseous form and thereby separate it from contaminants and other undesirable
elements commonly found in ground and surface water. Distillation heats raw (untreated) water
until the water reaches its boiling point and begins to turn into a gas.
(iii) Membrane Technology: Membrane technologies like RO (reverse osmosis) push water
through a semi-permeable membrane to filter out nearly all dissolved .
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
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for beginners, providing thorough training in areas such as SEO, digital communication marketing, and PPC training in Noida. After finishing the program, students receive the certifications recognised by top different universitie, setting a strong foundation for a successful career in digital marketing.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
1. HARDNESS OF WATER
INTRODUCTION.
Water is very essential substance for all living things. Over 70% of the earth is water and there
are different sources of water for daily use. These sources include rivers, lakes, wells, ponds,
springs, and streams.
Water can also be obtained from taps that are supplied with treated from the local or nearest
water works.
In some places, water lathers easily with soap, this water is said to be soft. In other places, the
same amount of soap would give scum and very little lather. This water is said to be hard. Scum
is an insoluble layer of impurities that accumulates at the surface of a liquid, especially water.
Hardness of water is caused by dissolved calcium and magnesium compounds. They include
calcium, calcium hydrogen carbonate, magnesium sulphate and magnesium hydrogen carbonate.
For example
Calcium sulphate + sodium stearate → calcium stearate + sodium sulphate
(Hardness) (Soap) (Scum)
The soap and the hardness join to form scum. The other compound sodium sulphate which is
formed dissolves in water.
Calcium hydrogen carbonate is the most common cause of hardness of water. It forms when
rain falls on the rocks of limestone and chalk, which are mainly composed of the insoluble
calcium carbonate. As the rain falls through the air, it dissolves carbon dioxide to form weak
acidic solution. This solution is able to attack the calcium carbonate to form the soluble calcium
hydrogen carbonate.
Water + carbon dioxide + calcium carbonate → calcium hydrogen carbonate
H2O(l) + CO2(g) +CaCO3(s) → Ca (HCO3)2(aq)
Dolomite and gypsum are other rocks that are sources of hard water.
TYPES OF HARDNESS OF WATER.
There are two types of hardness of water, namely Temporary and Permanent hardness of water.
Hardness caused by calcium hydrogen carbonate is called temporary hardness because it can be
removed by boiling the water.
2. Ca (HCO3)2 (aq) → H2o(l) + CO2 (g) + CaCO3 (s).
Hardness caused by other calcium and magnesium compounds is called Permanent Hardness.
This is because boiling does not affect it.
HOW TO REMOVE PERMANENT HARDNESS OF WATER
Permanent hardness of water can be removed by:
i) Distillation; This gets rid of both temporary and permanent hardness.
ii) Adding sodium carbonate (washing soda); This is added to the water to precipitate calcium
carbonate. It removes both types of hardness of water for example, its reaction with sodium
sulphate is;
Calcium sulphate+ sodium carbonate →calcium carbonate
CaSO4 (aq) + Na2CO3(aq) → CaCO3(s) + Na2SO4 (aq)
iii) Ion exchangers; These can remove both types of water hardness by removing all the
calcium and magnesium ions in the water.
An ion exchanger is a container full of small beads. These are made of special plastic called
ion exchange resin. This has ions for example, sodium ions that are weakly attached to it.
When hard water is passed through the ion exchanger, the calcium and magnesium ions in the
water change places with the sodium ions and attach themselves to the resin. The calcium and
magnesium ions are therefore left behind in the resin as the soft water flows out with the sodium
ions.
After some time, all the sodium ions will have been replaced and the exchanger cannot
remove hardness anymore. This is resolved by regeneration of the resin by pouring a
concentrated solution of sodium chloride into the exchanger.
The sodium ion push the calcium and magnesium ions off the resin, making the ion exchanger
ready for use again.
3. The Ca2+ from the hard water replaces the Na+ ions in the ions exchanger; softened water
(with Na+ ions) leaves the ion exchanger to be used in the household.
The sample of water that do not lather easily are of hard water. These include the sea water and
sometimes the tap water. The boiled, distilled and rain water easily form lather with soap and are
therefore soft water.
ADVANTAGES AND DISADVANTAGES OF HARD WATER.
1) ADVANTAGES:
i) It tastes better due to dissolved compounds.
ii) It provides useful calcium for the growth of bones and teeth.
iii) The formation of lime scale in pipes forms a sort of insulation which prevents the water in
the tap from coming into contact with the metal of the pipe. This prevents pipe corrosion and
poisonous metal salts from getting dissolved in the water.
2) DISADVANTAGES:
i) The temporary hardness of water causes limescale in water boilers, hot water pipes, kettles
and other appliances, this makes them less efficient.
Scaling can also cause blockage in the appliances and has to be removed from time to time.
ii) Hard water needs more soap than soft water, so it means a lot of soap is wasted.
4. iii) Hard water leaves scum deposits that are difficult to wash out and causes damage various
articles.
WATER TREATMENT.
Before water is used in the public water supply, it has to be treated, not to make it pure but to
make it safe to drink.
The various stages include:
1. Filtration to remove any large objects such as algae or parasites.
2. Precipitation of mineral salts such as iron salts using alum (calcium hydroxide).
3. Filtration through a sand bed- this is a biological process. A gelatinous layer is used ton trap
unwanted particles.
4. Chlorination. Treating with chlorine kills harmful bacteria in the water- this is a disinfectant.
5. Fluoridation. Adding sodium fluoride in small quantities. Fluorides harden the enamel on
teeth and reduce dental problems. Not all water is treated in this way.
As much as a supply of clean, safe water is essential to ensure good health, we must not forget
that safe disposal of used water is of equal importance. This becomes especially important when
people live close together in towns and cities.
In a city it is essential to have a system for the disposal of used water. We call this a sewage
system.
The processes involved in sewage treatment plants are outlined below.
1. The sewage that enters a treatment plant contains debris that might damage the pumps and
machinery such materials are removed by screens or vertical bars. After removal, this debris is
burned or buried.
2. The waste water then passes through a grinder where leaves and other organic materials are
reduced in size for efficient treatment and removal later.
3. Next, grit is removed in grit chambers. The grit is removed and the disposed of as sanitary
landfill.
4. With grit removed, the water passes into a sedimentation tank, in which organic materials
settle out and are drawn off for disposal. An alternative to sedimentation that is used in the
treatment of some waste water is flotation, in which air is forced into the waste water under
pressure of 1.75 to 3.5kg mâ•»². The waste water, supersaturated with air, is then discharged
5. into an open tank, there the rising air bubbles cause the suspended solid to rise to the surface,
where they are removed.