Posted by Jhiegzh on Sunday, June 6, 2010 in
Concentration of a solution refers to the weight or volume of solute in a specified amount of solution or solvent. According to chem.purdue.edu, it is a macroscopic property, meaning it describes the behaviors or characteristic of a sample which is large enough to see, weigh, manipulate, handle, etc.

It can be expressed in variety of methods:
1.) Specific Gravity is equal to:
                        
                            since density is equal to mass/volume
                            Therefore Specific Gravity is equal to:
                        

2.) Mass Percent refers to the mass of solute contributed to the total mass of solution. Mass Percent is equal to:
                        

3.) Volume Percent refers to the volume of solute contributed to the total volume of solution. Volume Percent is equal to:
                        

4.) Molarity (M) refers to the number of moles of solute present in a liter of solution. Molarity is equal to:
                        

5.) Molality (m) refers to the number of moles of solute present in a kilogram of solvent. Molality is equal to:
                        

6.) Normality (N) refers to the number of gram-equivalents of solute present in a liter of solution. Normality is equal to: 
                        

With the aid of the 6 formulas indicated above...
Have a try in solving the SAMPLE PROBLEMS:
1.) What is the molality of a solution prepared by dissolving 70.0g of glucose in 850g of water?
2.) A pickling liquor is prepared by dissolving 215mL of concentrated HCl solution in 450mL of water. What percent of the liquor is acid?
3.) Calculate the normality of a solution prepared by dissolving 45.0g of barium hydroxide in enough water to make 500mL of solution.
32 Responses to “Concentration of a Solution”:
  • Chemistry na naman! :)) Hahahahaha! ^_^ Babalikan ko ito. Muahahaha! *evil laugh*

  • Bakit mo naman babalikan?

  • wow! haha..thanks so much for sharing! do we have to solve those problems? :D okay, i'll try! :) huhu..maybe i'll make a mistake.. :( correct me if i'm wrong! :D

    1.) What is the molality of a solution prepared by dissolving 70.0g of glucose in 850g of water?

    m = 70.0g/850g
    m = 0.0824 g <<

    2.) A pickling liquor is prepared by dissolving 215mL of concentrated HCl solution in 450mL of water. What percent of the liquor is acid?

    215mL/450mL x 100% = 0.48 = 48% <<


    3.) Calculate the normality of a solution prepared by dissolving 45.0g of barium hydroxide in enough water to make 500mL of solution.

    N = 45.0g/500mL
    N = 45.0g/5L
    N = 9 g/L <<

  • nose hemorrhage...tabang nurse

  • @Nice: Thanks for the try!...:) Uhmmm! Practice lang ^^

    @Ghienox: Wooaaah!

  • @Jhiegzh: you're welcome! :D yeah! :) so, how are my answers? haha.. :)) are they correct?

  • Shucks! 2.25 lng ako sa Chem1 at Chem2 hehehe...

  • Wow. Chemistry. I never really learned a lot about chem back in high school. Glad I don't have to take it this college.

    Ironically, my parents are both chemists. Haha. :)

  • @NIce: Take note for your units! Unit for molality is (m) not g and for normality is N! BEfore you solve you need to determine first the number of moles!

    @Jag: OK lang yan ah! Pasado naman yan dba?

    @Umi: Wow, opposite pla kau ng parents mO! ^^

  • @Jhiegzh: ahh! okay! thanks! :) so i got correct on number 2? yay! haha.. :))

  • @Nice: THis is a CHEM1 topic!

  • Waaa! Chemistry! i remember pinagalitan ako ng prof ko kasi di daw ako nakikinig! nagnonotes kasi ako tas dinadaldal pa ko ng seatmate ko. huhu. i hate chemistry. :(

  • @BubbleS: Opposite here pero depends na rin sa topic! hahaha

  • Bagsak ako sa chemistry kaya di ako maka-relate .. haha.. tinutulugan ko lang yata to.. nosebleed ako sa formulas.. sa formula lang yata ng IVF computation ako hindi dinugo e.. whahaha

  • @Mharliz: Aw ah! WOaaah!

  • haha.. e kasi naman.. kasi.. bobo talaga ako sa math.. ang alam ko lang me plus him equals love.. haha joke..

    wala makulit ako ngaun.. wag ka ng umangal.. haha

  • 1] Given:
    Mass of solute = 70g
    Mass of solvent = 850g -> 0.85kg
    Molecular Weight of C6H12O6 -> 180g/mol

    mole of C6H12O6 = 70/180 = 0.389 moles

    Molality = 0.389/0.85 = 0.458 molal



    2] Given:

    HCl = 215mL
    H20 = 450mL

    Applying Percent Volume formula, since we need the volume percentage of liquor (HCl), we have

    450mL / 215mL * 100% = 2.09%

    Even if you convert mL to L, the answer is still the same.

    3] Given:

    Ba(OH)2 = 45g
    H20 = 500mL

    Since we have a basic chemical (Barium Hydroxide), Normality can be solved by the formula

    N = (Mass of solute/equivalent weight of base)/Liters of solution

    to get the equivalent weight:

    Formula weight / No. of available hydroxides per formula unit

    171 / 2

    = 86

    substitute it to the normality formula:

    (450/86)/500

    we have: 0.0105N or equivalents/L.

    I hope tama ako kasi poor ako sa Chemistry! T_T

  • @Juls: Bakit mo kinuha ang molecular weight..Uhmm! I cant tell the answer! Pero nice try!

    @Mharliz: Hindi tlga ako aangal! naks!

  • ayokong sagutin to..hmp!

    hehehe high school days ko pa to nakuha..i think 2nd year namin..kaya ayoko na sawa na ako sa chem..wahaha

  • @Superjaid: Ok lang ah! I will not reveal the answer though!...^^

  • Nakakainis. ;)))) I took Chem nung 1st sem last school year. Daaaaamnnn. Okay, nakalimutan ko agad. Haha. Pero hindi naman ako nagma-major niyan so okay lang. ;)) Nosebleed eh.

  • @Keiyt: OK lang yan ah...Ako nga rn eh! LOL!

  • I love Chemistry! hahahaha.. :)) even though there are a lot of headache-giving formulas! waa..

  • @Nice: We are same! ^^

  • oh my..kuya jose naman hehehe i hate chem! prmise hehehhehe..5 units pa naman chem namin..gs2 ko lang pag lab..pero pag chem lec naku terror ang prof namin..yan din inaral namn last year..ngaun physics n kmi :)

  • @Rose: Ok na nga yun eh! ^_^....:)

  • Ewan ko nga ba eh. Hahahahaha! Baliw lang ako nung sinagutan yan! :PP

  • @Juls: Uhmmm...Hahahaha

  • skt sa ulo yang chem na yan grabe hehe :)

  • @Yvette: Hehehe..Oo! Woaaah ^^

  • This certainly helps chemistry students! I've touched a lot on chemistry, the most common unit of concentration is the molarity. Instead of litre, I often express molarity in terms of cubic decimetre - but both are equivalent.

    As I moved on to biochemistry, I encounter concerntrations in terms of micromolar and milimolar - to talk about DNA and protein samples!

  • @Boon: Yeah! I knew that!

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