Hardness of Water | Temporary | Permanent

Summary

This video delves into the concept of water hardness, a property influenced by dissolved calcium and magnesium salts. Hard water fails to lather with soap due to these salts, leading to scum formation. The hardness is categorized into temporary, caused by bicarbonates and carbonates removable by boiling, and permanent, from other salts like sulfates and chlorides, requiring treatments like zeolite or ion exchange for removal. The video promises to explore hardness calculations in subsequent lectures.

Takeaways

• 💧 Water hardness is a property that affects how water interacts with soap, preventing it from lathering properly.
• 🔍 Hard water contains dissolved salts of calcium and magnesium, which are responsible for its hardness.
• 🧼 The inability to lather with soap is a key indicator of water hardness due to the reaction between calcium/magnesium ions and soap's fatty acid salts.
• 🌟 There are two main types of water hardness: temporary and permanent, distinguished by the salts present and their reactivity.
• 🕒 Temporary hardness is caused by bicarbonates and carbonates of calcium and magnesium, which can be removed by boiling the water.
• 🔬 Permanent hardness is due to other salts like chlorides, sulfates, nitrates, and phosphates, which do not remove easily by boiling.
• 🧪 A simple test to identify hard water is by adding soap and observing if a white precipitate, or scum, forms, indicating the presence of hardness.
• 🌡 Boiling water can convert bicarbonates to carbonates, which then precipitate out, thus reducing temporary hardness.
• 🛠 To remove permanent hardness, methods like using zeolite, lime soda process, or ion exchange resins are employed.
• ⏩ The lecture will continue with calculations related to water hardness in the next session.

Q & A

What is water hardness?

Water hardness is a property of water that prevents it from lathering with soap properly due to the presence of dissolved salts of calcium and magnesium.

Why does hard water not lather with soap?

Hard water contains calcium and magnesium salts that react with the sodium or potassium salts of higher fatty acids in soap, leading to the formation of a precipitate or scum, which prevents proper lathering.

What are the two main types of water hardness?

The two main types of water hardness are temporary hardness and permanent hardness.

What causes temporary hardness in water?

Temporary hardness is caused by the presence of bicarbonates and carbonates of calcium and magnesium in the water, which can be removed by boiling.

How can you remove temporary hardness from water?

Temporary hardness can be removed by boiling the water, which causes the bicarbonates and carbonates to convert into precipitates that can be filtered out.

What is permanent hardness and how is it different from temporary hardness?

Permanent hardness is caused by salts other than bicarbonates and carbonates, such as chlorides, sulfates, nitrates, and phosphates of calcium and magnesium, and cannot be removed by boiling alone.

What are some methods to remove permanent hardness from water?

Permanent hardness can be removed using methods like ion exchange, zeolite, or lime soda processes, which involve the use of compounds like zeolite, calcium hydroxide, or sodium carbonate.

Why is it important to identify water hardness?

Identifying water hardness is important to determine the suitability of water for various applications, such as domestic use, agriculture, and industrial processes, where hard water can cause scaling and other issues.

What is pseudo hardness and how does it differ from temporary and permanent hardness?

Pseudo hardness, also known as fake hardness, is not discussed in detail in the script but generally refers to hardness caused by certain metals other than calcium and magnesium, which can be removed by simple settling or filtration.

How can you differentiate between hard and soft water?

Hard water can be identified by its inability to lather with soap and the presence of a white precipitate or scum, while soft water will lather easily and not produce a precipitate.

What are the potential issues caused by hard water in domestic use?

Hard water can cause issues such as scaling in pipes and appliances, reduced efficiency of water heaters, and difficulty in cleaning with soap, which can affect the quality of laundry and dishes.

Outlines

00:00

💧 Understanding Water Hardness

The first paragraph introduces the concept of water hardness, explaining it as a property of water that prevents it from lathering with soap effectively. It is caused by the presence of dissolved salts of calcium and magnesium. The speaker discusses the reaction between these salts and soap, which typically results in a precipitate or scum, indicating hard water. The paragraph also distinguishes between two types of hardness: temporary and permanent, with a brief mention of pseudo hardness. The focus is on how the presence of calcium and magnesium salts in water leads to hardness and the inability to lather with soap.

05:02

🔍 Temporary vs. Permanent Hardness

The second paragraph delves deeper into the two types of water hardness: temporary and permanent. Temporary hardness is caused by bicarbonates and carbonates of calcium and magnesium, which can be removed by boiling the water. This process converts the bicarbonates into carbonates, leading to the formation of precipitates that can be filtered out. Permanent hardness, on the other hand, is due to other salts such as chlorides, sulfates, nitrates, and phosphates, which do not convert into precipitates upon boiling. The paragraph also introduces the terms 'carbonate hardness' for temporary and 'non-carbonate hardness' for permanent, highlighting the difference in the ions responsible for each type.

10:03

🛠 Methods to Remove Hardness

The third paragraph discusses methods to remove water hardness. For temporary hardness, boiling is an effective method as it converts bicarbonates into insoluble carbonates, which can then be filtered out. For permanent hardness, more complex treatments are required, such as the use of zeolite, lime soda process (involving calcium hydroxide and sodium carbonate), or ion exchange resins. The paragraph concludes by summarizing the discussion on water hardness and its types, with a预告 of the next lecture focusing on the calculation of hardness.

Keywords

💡Hardness of Water

Hardness of water refers to the presence of certain salts, primarily dissolved salts of calcium and magnesium, which prevent soap from lathering properly. In the video, hardness is a key property that affects the usability of water, especially in cleaning applications. The script explains that hard water will not produce lather with soap due to the reaction between the calcium and magnesium ions and the fatty acid salts in soap, leading to the formation of a precipitate known as scum.

💡Dissolved Salts

Dissolved salts are impurities that are mixed into water to the point where they are not visible and cannot be removed by physical means such as filtration. The video emphasizes that the presence of dissolved salts of calcium and magnesium is what characterizes hard water. These salts are invisible to the naked eye but can be detected by their effect on soap lathering.

💡Soap

Soap is mentioned as a sodium or potassium salt of higher fatty acids. In the context of the video, soap is used as a test to determine water hardness. The interaction between soap and the calcium or magnesium ions in hard water leads to a reaction that forms a precipitate, indicating the presence of hardness.

💡Precipitate

A precipitate is a solid that forms from a solution during a chemical reaction. In the video, the reaction between soap and the dissolved salts in hard water results in a precipitate, commonly referred to as scum. This is a visual indicator used to identify the presence of hardness in water.

💡Temporary Hardness

Temporary hardness is a type of water hardness that can be removed by boiling. It is caused by the presence of bicarbonates and carbonates of calcium and magnesium. The video explains that when such water is boiled, these compounds are converted into precipitates that can be removed, thus softening the water temporarily.

💡Permanent Hardness

Permanent hardness is a type of water hardness that cannot be removed by boiling. It is caused by salts other than bicarbonates and carbonates, such as chlorides, sulfates, and nitrates of calcium and magnesium. The video indicates that to remove permanent hardness, more complex treatments like ion exchange or the use of certain compounds are required.

💡Bicarbonates and Carbonates

Bicarbonates and carbonates are specific types of salts that contribute to temporary hardness. The video explains that these salts are responsible for the temporary inability of water to mix with soap due to their reaction to form a precipitate. However, this hardness can be reversed by boiling the water, which converts these salts into less soluble forms.

💡Zeolite

Zeolite is mentioned as a compound that can be used to remove permanent hardness from water. In the context of the video, zeolite is an example of an ion-exchange material that can selectively bind to calcium and magnesium ions, thus softening the water by reducing its hardness.

💡Lime Soda Process

The lime soda process is a method for removing permanent hardness, as discussed in the video. It involves the use of calcium hydroxide (lime) and sodium carbonate (soda) to precipitate out calcium and magnesium ions from the water, thereby reducing its hardness.

💡Ion Exchange Resin

Ion exchange resin is another method for removing hardness, particularly permanent hardness, from water. The video describes it as a material that can exchange sodium ions for calcium and magnesium ions, effectively reducing the concentration of hardness-causing ions in the water.

Highlights

Definition of water hardness as a property that prevents soap from lathering properly.

Presence of dissolved salts of calcium and magnesium causes water hardness.

Hard water's interaction with soap leads to a white precipitate known as scum.

Differentiation between dissolved, suspended, and biological impurities in water.

Soap is identified as the sodium or potassium salt of higher fatty acids.

Chemical reaction between hard water minerals and soap results in scum formation.

Explanation of temporary hardness due to bicarbonates and carbonates of calcium and magnesium.

Temporary hardness can be removed by boiling water, which converts bicarbonates to carbonates.

Permanent hardness is caused by salts other than bicarbonates and carbonates, such as sulfates and chlorides.

Permanent hardness is more difficult to remove and requires processes like zeolite, lime soda, or ion exchange.

Temporary hardness is also referred to as carbonate hardness, while permanent hardness is known as non-carbonate hardness.

The practical test for water hardness involves adding soap and observing the formation of scum.

The video differentiates between alkaline hardness (temporary) and non-alkaline hardness (permanent).

The importance of identifying water hardness for its application in various processes.

The video concludes with a preview of the next lecture focusing on the calculation of water hardness.

Transcripts

hello everyone

so uh today i will discuss about a

property of water

which is known as hardness of water

in the previous video i discussed about

what are the basic sources of water

and what are the impurities which could

be possibly present in the water

based on that if those impurities are

present

they may render a property called

hardness to the water

so what is that it's basically a

property of water

by virtue of which it does not give

leather with soap

properly so if the water

contains certain salts

due to the presence of dissolved salts

of calcium and magnesium

there are two three things in this

definition first of all

the salts are dissolved in nature i hope

you remember

that the impurities could be dissolved

could be suspended

and could be biological so in the

category of dissolved salts

especially of calcium and magnesium if

these salts are present in the water

the water is known as hard water so

if a hard water is taken and as per the

definition

it do contains calcium and magnesium

salts

dissolved in it now if you treat this

kind of water

with soap this particular water

is not going to give you leather with

soap properly

and this property is known as hardness

of water

if the property because of which water

does not

leather with soap properly now why does

it does not leather with soap

because certain salts like that

of calcium and magnesium say for example

calcium chloride

is present in the water now if you take

this water with soap

i hope you remember that the soap was

sodium

or potassium salt of higher fatty acid

so it could be n a it could be k sodium

or potassium salt of higher

fatty acid rco h

fatty acid and then in this r since i'm

saying it's higher fatty acid

this r uh could be cn h2n

plus one so let's say if i take steric

acid

it could be c 17 h 35 that is

r then c o o n a

so this becomes sodium stearate so if we

have taken this kind of compound

this is a so right if you take oleic

acid

it will become oleate if you take

palmitic acid it will become palmitate

so basically soap is sodium or potassium

salt of

higher fatty acid now imagine you are

having a hard water which is having

calcium or magnesium salt

and you treat it with soap so what do

you think the reaction would be

obviously these are going to react so

this is the positive ion here

this is the positive ion here so at the

end

uh you will be having a displacement

reaction

so herein if i write it like this

and then like this so overall if i want

to

you know balance out the reaction i

could uh write to

yeah so this is a precipitate and you

call it as a scar

this is the down arrow which shows it's

a precipitate so

if the water is hard if it is having

presence of calcium magnesium ions

which are dissolved in nature so you

cannot see them

but they are present in the water what

do they do they render hardness to the

water

so if that water you take and you treat

it with soap

you'll be immediately able to identify

because of the white precipitate

which you call it as a scum you'll be

able to identify

that the water is hard so basically

hot water and soft water is the first

key you need to find out whether the

water is hard or not

then only you can utilize it in your

further application

so if it is hard that means it's not

going to give leather with soap properly

and that too due to the presence of

dissolved salts of

calcium and a magnesium so i hope

if i simply now write another salt

like if i take magnesium sulfate i think

you'll be able to react it with this and

you'll be able to understand

that here you will get magnesium

stearate

and you can change the anion here also

so i think you are able to understand

the fact

now there are two basic types of

hardnesses

temporary and permanent there is one

more

which is known as uh pseudo hardness

that is a fake hardness i'll tell you

later on about this

but as of now we are going to discuss

about temporary and permanent hardness

let's go ahead with it temporary

hardness

what do you think it is the word itself

suggests

that it is temporary in nature that

means

it is a hardness hardness means first

point

is not going to give leather with soap

properly

don't forget second point why dissolved

salts of calcium

and magnesiums are present now if

these salts some of the salts they may

render the hardness in temporary nature

means for a short period of time and

some of the salts may remain present in

the water

for long so temporary hardness is

nothing but

the hardness due to which there will be

no leather definitely

but here the salt which are present

are of calcium magnesium definitely what

is the difference

the difference lies in which salt i'm

talking about

bicarbonates and carbonates so only

and only if bicarbonates

and carbonates of calcium and magnesium

are present

you can call that hardness is temporary

in nature

because it does not last long you can

easily remove it how can you remove it

by boiling the water so these are the

example

and in fact magnesium carbonate will

also

come here so basically these four salts

are responsible

for rendering hardness to the water and

that too

temporary in nature temporary you can

remove them

easily now coming to the next one

obviously per month so in comparison to

that temporary

which was easily removed by boiling

obviously this type of hardness

you cannot easily remove by boiling that

prevents the leather quite permanently

and here also

you need to specify which salts

are responsible for it so if i can

say conveniently except by carbonate and

carbonate

all salts are responsible for permanent

hardness

chlorite sulfates nitrates phosphates

etc

right so it would be very easy for you

to understand by the formula

itself like if i write magnesium sulfate

as of now

you can see that it is not bicarbonate

and carbonate

that means it's permanent in nature

right

if i write magnesium carbonate what

would it be

it's a carbonate so temporary let's say

if i write calcium carbonate

what it is temperature like

if i write calcium chloride that's not a

carbonate bicarbonate

so obviously permanent let's say calcium

bicarbonate

what it would be obviously temporary so

with the help of

the formula itself you should be able to

understand

that if it is bicarbonate and carbonate

it is temporary and rest all salts rest

all

comes in the category of permanent so

just to revise the fact

one more time temporary hardness is

quite

temporary in nature as simple as that

that's quite permanent in nature but the

difference

lies in the reason behind it here the

reason is bicarbonates and carbonates

here all salts except bicarbonate and

carbonate

you can write one example in both of the

categories

now it is also known as alkaline

hardness

and it is also known as non-alkaline

hardness can you identify

why i think it will focus

on the ions which are responsible

bicarbonates and carbonates

right the ions or

maybe hydroxide uh then

you can say that these are alkaline

image while these ions are not alkaline

they're quite acidic you can see there

right so you can call them as non alkali

at the same time carbonate hardness

i guess you remember it was because of

bicarbonate and carbonate

so the another name of temporary

hardness would be carbonate hardness

another name of permanent hardness would

be non-carbonate heartless

the important point here is you can

remove it by boiling

so what happens is if you boil let's say

if you have

magnesium bicarbonate and if you heat it

it changes to magnesium hydroxide

fine and then you can balance out the

reaction by writing it co2 and on

so basically magnesium gets converted to

magnesium hydroxide

calcium gets converted to calcium

carbonate so when you boil the water

this is the sign triangle is the sign of

heating so when you're heating the water

when you're boiling the water

these ions gets converted into their

respective

precipitate and then you can simply

filter them up

so by filtering by simply removing uh

you can remove them

right so by simple boiling they are

going to convert their

into their respective stable form and

that is how

they render the hardness in a temporary

manner

because they easily get converted into

their stable form

when these of the ions are quite stable

and they don't undergo this reaction

very easily

right for them you have to use certain

compounds

like you can use zeolite or permuted you

can use lime soda

lime uh would be calcium hydroxide

soda would be sodium carbonate then you

can use iron exchange resin

etc so these points are to be like

processes are to be used

in order to remove the permanent

hardness so i think

with that i'm able to give you a glimpse

on

what is uh what do you understand by the

term hardness

and then and its types so today uh what

we have discussed

is only hardness and its types in the

next lecture

i would focus more on calculation of

hardness

uh that's all for today so thank you