Question

Calculate the degree of hardness of a water sample containing 0.001 mole of Mgso4 dissolved in 2 litres of water is ?

Answer 1

sorry, @open_study1 , I have to revise this chapter.. I forgot the concepts :(
but u have to convert to ppm unit

Answer 2

but how?? the answer should be 50ppm............

Answer 3

why did you invite me to this thread @open_study1

Answer 4

yes

Answer 5

This is the same old question, asked by you aka @shameer1

Answer 6

@apoorvk plzz help

Answer 7

can anyone solve this plzzz

Answer 8

@kryten

Answer 9

Perhaps....
mass of MgSO4 = 0.001 x (24.3 + 32.1 +16.0x4) = xxx
ppm = (mg/L) = (xxx/1000) / 2 = ...

Answer 10

@Vincent-Lyon.Fr plzz help

Answer 11

Sorry, I do not know how "degree of hardness" is defined.

Answer 12

Is it like ... ppm?

Answer 13

ppm of what?

Answer 14

caso4 i think

Answer 15

Mg2+ in this case?
Since Mg2+ in water is considered as hard water... Not sure though :|

Answer 16

we always have to take cas04...

Answer 17

sorry caco3

Answer 18

From what I've learnt, both Mg2+ and Ca2+ can make hard water.
Moreover, in your case, you're only given MgSO4, how come you can have Ca2+ ?

Answer 19

yes u r correct but after solving ur eq i got a wrong answer .........

Answer 20

maybe i have gone wrong

Answer 21

can u plzz check it

Answer 22

yes this is defined as 'ppm'

Answer 23

Instead, do you mind showing your workings?
I don't mind helping you check your answer :)

Answer 24

no of moles =0.0005 mgso4 = 0.0005moles caco3

Answer 25

Where did you get ''no of moles =0.0005 mgso4'' ?

Answer 26

Where from did you get "0.0005"?

Answer 27

lol

Answer 28

"yes u r correct but after solving ur eq i got a wrong answer ........."

Shameer, this is going too far once again! Code of Conduct of OS states that you have to show your work in order to receive help. Not the other way round.

Showing your work does not mean writing down the answers from the answer sheet , but actually explaining with WORDS what you are doing.

Answer 29

0.0005 moles in 1 litre

Answer 30

in the question given 2 litre so for 1 litre

Answer 31

ppm should be calculated in 1litre

Answer 32

Okay right, 0.0005 moles in one liter - okay.
How many moles of water in 1 liter now?

Answer 33

Dividing 0.001 by 2 is not what I call "showing your work"!

ppm, like %, is not calculated in one litre but in any amount.

Answer 34

how can i show my work.....plz tell

Answer 35

1. type it out
2. write it, then scan it/take a photo of it, after that, upload it

Answer 36

Mna just tell me the no. of moles of water in 1000 gms, or 1000ml or 1 liter of it? What's the molar mass of water first of all?

Answer 37

*Man

Answer 38

18

Answer 39

MM of water h20 = 18

Answer 40

is that correct

Answer 41

no of moles =55

Answer 42

yes, sire. in fact 55.55 to be exact.

So, you got no. of moles of water in a liter.
You got no. of moles of the impurity in a liter too.

Can you find the ppm of the impurity in the sample now?

Answer 43

how?

Answer 44

ppm = parts per million.

just like percentage is 'parts per 100'

helps?

Answer 45

have to multiply by 10^6???????

Answer 46

Yup.. show you working once.

Answer 47

ok

Answer 48

0.0005/55*10^6 is that correct

Answer 49

You mean that whole fraction multiplied by a million right?

Answer 50

s

Answer 51

Yup, seems right to me then. @Callisto what do you think?

Answer 52

no i am not getting the answer the answer should be 50ppm

Answer 53

Okay try to calculate everything in terms of gram once - I think that should work.

Yes, instead of moles, take the grams of CaSO4 present. What do you get?

Answer 54

Hmm, seems I was wrong - ppm can mean by weight as well. Sorry for that @open_study1

Answer 55

And in the case of degree of hardness, ppm by weight is considered - though it doesn't make sense to me why.

Answer 56

Mass of MgSo4=120*10^-3 g.....1
Mass of water = 2000g......2
ppm of mgso4 in water = 1*1000000/2=60ppm
i think ...

Answer 57

@SMISHRA can u ans it

Answer 58

The answer should be 50 ppm

Answer 59

Here it is...
no. of mole of MgSO4 in 1L = 0.001/2 = 0.0005
0.0005 mole of MgSO4
= 0.0005 mole of CaCO3
= 0.0005mole of CaCO3 in 1L
= 0.0005 (40.1 + 12.0+16.0x3)
= 50mg in 1L

therefore degree of hardness of water sample = 50ppm

Answer 60

thanzzzzz

Answer 61

welcome :|

Answer 62

mg/L -> so ppm W/V right? But ppm is supposed to be dimensionless - then how this? o.O I am utterly confused right now :/

Answer 63

thanks a lot @Callisto - that cleared all my misconceptions - I was grossly wrong about this. :/

Answer 64

Welcome :)