Determining mass for solutions

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IneedhelpwithChem
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Determining mass for solutions

Post by IneedhelpwithChem »

Hi everyone. I have an assignment which requires me to solve this.
"Determine the mass of KClO3 required to make a 0.5M solution. Atomic masses: K = 39, Cl =35.5, O = 16"

Can someone please tell me what steps I need to go through to get the answer, what do I need to find? I know how to calculate molar mass and such, i'm just not sure of the steps I need to take to get the answer for the question.
Thanks in advance.
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ChenBeier
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Re: Determining mass for solutions

Post by ChenBeier »

0,5 M means 0,5 mol/l
Calculate molar Mass, this the weight for 1 mol. Calculate then for 0,5 mol. This mass put in a measured flask and fill up to 1l with water
IneedhelpwithChem
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Re: Determining mass for solutions

Post by IneedhelpwithChem »

Molar mass of KCLO3 is 39 + 35.5 + 16(x3) = 125.5
= 125.5g/ 1 mole
this is what I have so far, what next?
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ChenBeier
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Re: Determining mass for solutions

Post by ChenBeier »

No
The molar mass is not correct its 122,5 g/mol, but can you read above.
There is it written how to go further.
IneedhelpwithChem
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Re: Determining mass for solutions

Post by IneedhelpwithChem »

yes, so I have to divide the moral mass in half to get the answer for .5 mol? and then add water?? I don't understand completely
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ChenBeier
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Re: Determining mass for solutions

Post by ChenBeier »

Yes it is the half of this amount. This has to be dissolved in water to get 1 l.
IneedhelpwithChem
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Re: Determining mass for solutions

Post by IneedhelpwithChem »

wow........guess I overcomplicated it, thank you so much
IneedhelpwithChem
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Re: Determining mass for solutions

Post by IneedhelpwithChem »

Molar mass of KCLO3 is 39 + 35.5 + 16(x3) = 122.5
= 122.5g per 1 mole solution
Molar mass of KCLO3 for 0.5M solution = 122.5g divided by 2
= 61.25g per .5 mole solution
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ChenBeier
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Re: Determining mass for solutions

Post by ChenBeier »

IneedhelpwithChem wrote: Sat Nov 06, 2021 12:29 pm Molar mass of KCLO3 is 39 + 35.5 + 16(x3) = 122.5
= 122.5g per 1 mole solution
Molar mass of KCLO3 for 0.5M solution = 122.5g divided by 2
= 61.25g per .5 mole solution
The Molar mass is 122,5 g/mol. The mass of 0,5 mol is 61,25 g.
After dissolving it in water up to 1 l!!!! it is 0,5 mol/l
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