Experiment 20
Aim: To investigate the effect of solvent volume and number of extractions on the % of extracted product
Results:
Assume the volume of KA2/ cm3 = a(i) = x ; a (ii) = y ; a (iii) = z
Questions:
(c) 2NaOH (aq) + C2H4(COOH)2 (l) → C2H4(COONa)2 (aq) + 2H2O (l)
Ma (10)/ 0.05(x) = ½
Let concentration of C2H4(COOH)2 = a1 x 118 (Mr) = b1 g dm-3
Therefore the mass of succinic acid in 25 cm3 = b1 x 0.025 dm3 = m1 g
(d) Ma (10)/ 0.05 (y) = ½
Let concentration of C2H4(COOH)2 = a2 x 118 (Mr) = b2 g dm-3
Therefore the mass of succinic acid in 25 cm3 = b2 x 0.025 dm3 = m2 g
(e) Total mass = m1 + m2 = m3 g
(f)
Ma (10)/ 0.05(z) = ½
Let concentration of C2H4(COOH)2 = a3 x 118 (Mr) = b3 g dm-3
Therefore the mass of succinic acid in 50 cm3 = b3 x 0.05 dm3 = m3 g
(f) Smaller volume of extracting solvent will extract smaller amount of succinic acid
(g) Less volume of solvent used will be more efficient than using single larger volume, proven by total mass obtained by comparing 50 cm3 in a (i) and a (iii).
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9 comments:
teacher..i'm L6 newbie..
so do you have any recommendation of book(s) for chemistry?
i kinda lost coz i juz started my class and i wanna hear more apart frm ppl frm my surrounding...
thx teacher..
hope 2 hear frm you..
take care..
do you have the result of experiment 14?
saw tis on blogs..hope it helps others..=)
STPM Chemistry Experiment 14
Posted by Noor Shazreen Jamal at 1:33 PM
Topic: Qualitative analysis
Purpose: To determine the cations and anions of inorganic substances
Procedure:
1. Solids KA1 and KA2 are simple salts. Carry out the following experiments with solid KA1 to identify its cation and anion.
2. You are then required to carry out a few experiments to identify the cation and anion present in solid KA2. In all the experiments, the reagent should be added gradually until no further change is observed. Deduce what you can about KA1 and KA2. Observations should include details of colour changes, precipitates, and tests on gases evolved.
Tests on KA1
Add dilute hydrochloric acid to a small amount of solid KA1, then warm gently.
Observation: Solutions smells like vinegar.
Deduction: Solution contains CH3COO- ions.
Dissolve solid KA1 in distilled water and filter. Use separate portions of the filtrate for the following tests.
Add aqueous sodium hydroxide, then in excess.
Observation: A white precipitate is formed.
Deduction: Solution contains either Pb2+ ions, Zn2+ ions or Al3+ ions.
Add aqueous ammonia, then in excess followed by aqueous ammonium chloride.
Observation: Solution turns cloudy and a white precipitate is formed.
Deduction: Solution contains either Pb2+ ions or Al3+ ions.
Add aqueous iron (III) chloride, then warm.
Observation: Solution turns brown and a white precipitate is formed.
Deduction: Solution contains CH3COO- ions.
Add aqueous silver nitrate, followed by dilute nitric acid.
Observation: A white precipitate is formed.
Deduction: Solution contains CH3COO- ions.
Add aqueous disodium hydrogen phosphate.
Observation: Solution turns white and a white precipitate is formed.
Deduction: Solution contains Pb2+ ions.
Add aqueous potassium chromate (VI) followed by dilute hydrochloric acid.
Observation: A yellow precipitate is formed.
Deduction: Solution contains Pb2+ ions.
Identity of KA1: KA1 contains Pb2+ ions and CH3COO- ions.
Tests on KA2
Add concentrated hydrochloric acid and test for gas(es) evolved by using lime water.
Observation: Lime water turns chalky.
Deduction: The reaction releases carbon dioxide gas. Solution contains CO32- ions.
Dissolve KA2 in dilute nitric acid. Use separate portions of the solution for the following tests.
Add dilute sodium hydroxide.
Observation: A blue precipitate is formed.
Deduction: Solution contains Cu2+ ions.
Add potassium hexacyanoferrate (II).
Observation: Solution turns dark brown.
Deduction: Solution contains Cu2+ ions.
Identity of KA2: KA2 contains Cu2+ ions and CO32- ions.
do you have exp 19?
i'm newbbie in form 6 .. i need experiment 2 answer and how to calculate it.. any1 can help???
This is very helpful. Thanks goodness that this blog exist!
tanx....its really helpful..
its very very helpfull...thank you very much...i dont know wat wil happen to my chemistry if there is no this blog....thanks again...
Heya, sorry to ask a stupid question or anything but can I ask why is 0.05 used in the Ma(10)/0.05(x)=1/2? The molarity of Ka2 is 0.03 right? And the equation used is MV/MV=mol 1/mol 2, yes? May I know how you obtained 0.05? I'll appreciate it if you clarified that for me and my friends. Thanks.
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