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Topic: Grade 11 exam review question (dillution, find known substance)?  (Read 11599 times)

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Offline djay230

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We have the name of the substance (Calcium Chloride)
and we are supposed to find the name of the other possible substance which is currently unknown is either :

Sodium Acetate
Sodium Nitrate
Sodium Sulphate

We had to use a concentration of Calcium Chloride and mix it with the "unknown" solution (100ml of cacl, 50ml of the unknown) we drained it into filter paper and now we have the mass of the substances after being drained...i have no idea what to do, any ideas?

The precipitate that was drained with the filter paper is a white solid

i have no idea what to do!

Offline Arkcon

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #1 on: January 18, 2012, 08:37:07 PM »
OK, you have 4 different chemical names.  Chemistry doesn't work on names. ;)  So lets start by translating these names of chemicals you mixed into balanced chemical equations.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline djay230

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #2 on: January 18, 2012, 08:56:19 PM »
OK, you have 4 different chemical names.  Chemistry doesn't work on names. ;)  So lets start by translating these names of chemicals you mixed into balanced chemical equations.

Sodium Acetate
Sodium Nitrate
Sodium Sulphate

and Calcium Chloride so...

I am pretty new to chemistry, gonna need some help...i have no idea what to do

how would i find out which one is the unknown substance from

Sodium Acetate
Sodium Nitrate
Sodium Sulphate

?????????

Offline UG

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #3 on: January 18, 2012, 08:59:02 PM »
Have you learnt about solubility rules?

Offline djay230

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #4 on: January 18, 2012, 09:01:03 PM »
Have you learn about solubility rules?

not sure, please tell me why, i might have been sick that day, :(

i am really confused, i understood titration fine and the other units, but im really stuck on this one, trying to figure it out for hours can someone justplease help me?

Offline opti384

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #5 on: January 18, 2012, 09:01:53 PM »
As Arkcon said above, try to write down the chemical equations. The reactions that take would be double replacement reactions in concept.

Offline djay230

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #6 on: January 18, 2012, 09:07:08 PM »
As Arkcon said above, try to write down the chemical equations. The reactions that take would be double replacement reactions in concept.

i did that, it doesn't help at all...how do i find which one is the known substance that she gave me?

i am looking at 3 equations, BUT how do i find out which is the substance she gave me....


does anyone know the answer to this? Any teachers, university students? anyone thats above the grade 11?

Offline djay230

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #7 on: January 18, 2012, 09:08:18 PM »
OK, you have 4 different chemical names.  Chemistry doesn't work on names. ;)  So lets start by translating these names of chemicals you mixed into balanced chemical equations.

i dont think you understand the question, the teacher gave us an UNKNOWN substance, then calcium chloride, we mixed it...

she said the possible substances the unknown can be is

Sodium sulfate
sodium acetate
or
sodium nitrate

i dont know how to find out the unknown.

Offline opti384

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #8 on: January 18, 2012, 09:09:30 PM »
Can you show me what you did? If you indeed did them correctly, and consider the solubility rule as UG mentioned, you'll be able to identify the unknown solution.

Offline djay230

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #9 on: January 18, 2012, 10:01:45 PM »
Can you show me what you did? If you indeed did them correctly, and consider the solubility rule as UG mentioned, you'll be able to identify the unknown solution.

what do you mean solubility rule?

what i did was first take the cacl and dilute it with water

then use the given solution (it was a liquid)

mix the given solution with the dilluted cacl and then drain the precipitate in the paper filter

THE DRAINED PRECIPITATE WAS A WHITE SOLID!

Offline Polytriazole

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #10 on: January 18, 2012, 10:15:57 PM »
When you mixed the two solutions together, the ions swapped partners.  The other posters are saying you should write chemical equations to find out what those product compounds are.  One of those products precipitated out.  If you look up "solubility rules" in your textbook or online, those will help you pick which compound is the precipitate.

Offline Arkcon

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #11 on: January 18, 2012, 10:36:31 PM »
I want to see you write out balanced chemical reactions, using the symbolic letters used in the periodic table of elements, to describe the reactants, and the products.  Then, once you've determined the possible products, we will again use the periodic table of elements to try to figure out how we can differentiate the 3 possible products, by their mass.

This is how we help, on this forum.  We don't give complete answers, we give hints to help you learn for yourself.  Sorry are hints so far have been too subtle, but there's no need to retype the question again and again, we can scroll up and read it.  You're just lengthening your thread, pointlessly.

Here's another tip ... THE COLOR WHITE HAS NO MASS ASSOCIATED WITH IT.  Elements and compounds do however.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline djay230

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #12 on: January 18, 2012, 10:57:01 PM »
I want to see you write out balanced chemical reactions, using the symbolic letters used in the periodic table of elements, to describe the reactants, and the products.  Then, once you've determined the possible products, we will again use the periodic table of elements to try to figure out how we can differentiate the 3 possible products, by their mass.

This is how we help, on this forum.  We don't give complete answers, we give hints to help you learn for yourself.  Sorry are hints so far have been too subtle, but there's no need to retype the question again and again, we can scroll up and read it.  You're just lengthening your thread, pointlessly.

Here's another tip ... THE COLOR WHITE HAS NO MASS ASSOCIATED WITH IT.  Elements and compounds do however.


you dont understand, i dont know this chem stuff, it is pointless me writing it out on the forum when i did infront of me and its no help, the forum i understand you dont want to give answer so i dont learn, but i have no choice.

I do NOT understand ANY of it, its all infront of me, i've been looking stuff up the whole day what else do you want me to do?

can someone just explain to me the solubility rules and what is a precipitate? how does this all relate, etc.

i will learn in time, i will log off in 1 hour, if help is not provided i guess i fail the exam...no sympathy on this forum these days...begging for help and not even one chooses to explain anything to me.

w/e if this is how chem is going to be i think im just going to drop out, even my teacher would explain this to me but ive been dead sick for the past week and i cant get help on the internet...

Offline Arkcon

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #13 on: January 18, 2012, 11:25:47 PM »
*SIGH* There are two ways to solve this problem, one is easier than the other.  Please look up the term "solubility rules" in the index of your textbook.  Or do an online search.  See if something jumps out at you when you compare that info to the starting info you have in the assigned problem.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline UG

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Re: Grade 11 exam review question (dillution, find known substance)?
« Reply #14 on: January 18, 2012, 11:27:46 PM »
The calcium compound that is 'insoluble' is the precipitate.

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