₦airaland Forum

Maize247:
Politics apart Obi needs urgent psychological examination. Obi that's always very neat now turning into something else. His dressing now looking unpresidential and this particular has probably not been changed in the last four days.

My advice, if Obi insists on wearing only black, at least, Obidents should be able to afford as many as possible.

Karemarealty288:
You Papa no reach to be Obi's gateman talk more of driver. Show us your Papa and I will give you 50k cash if your father has University degree....I challenge you.

BlackKafka:
Navy blue is the default colour for power suits.

BlackKafka:
By your logic funeral undertakers and the Nigeria Police should be in the Mensa club.

Sparrk007:
I love this man but his love for black clothes just dey fear me

Oduok:
Chemistry practical has three questions.

Question 1 is quantitative analysis (titration). This year we expect titration between a strong acid and weak base. The base will be a salt with water of crystalization.

Question 2 is qualitative analysis. This year we expect analysis of an organic and inorganic compound.

Question 3 is always general chemistry theory question.

This is not expo. It is for practice purpose.

Feel free to leave your questions, comments and contributions.



Question 1
A is a solution containing 0.100 moldm-3 of hydrochloric acid. B is a solution containing 5.0 g per dm3 of hydrated sodium trioxocarbonate (iv), Na2CO3.xH2O.

(a)Put A into the burette and titrate it against 20.00 cm3 or 25.00 cm3 portion of B using methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used.

Equation for the reaction:
Na2CO3.xH2O(aq) + 2HCl(aq) 2NaCl(aq) + CO2(g) + (x+1)H2O(l)
(b)From your results, calculate the:
(i)Concentration of B in moldm-3.
(ii)Molar mass of Na2CO3.xH2O.
(iii)Value of x in Na2CO3.xH2O.
[H = 1.0, C = 12.0, O = 16.0, Na = 23.0]

ANSWER TO QUESTION 1
1.(a) Volume of pipette used = 25.00 cm3.
Indicator used = Methyl orange
Burette Reading 1st Titre 2nd Titre 3rd Titre
Final volume of A (cm3) 8.80 17.50 26.30
Initial Volume of A (cm3) 0.00 8.80 17.50
Volume of A used (cm3) 8.80 8.70 8.80

Average volume of Acid used = (8.80 + 8.70 + 8.80) / 3
= 26.3/3 = 8.77cm3

(b) (i) Concentration of B in moldm-3:
(Ca x Va)/(Cb x Vb) = A/B
(0.10 x 8.77)/(Cb x 25.00) = 2/1
Cb = (0.10 x 8.77)/(25.00 x 2) = 0.877 / 50 = 0.0175 moldm-3.

(ii) Molar mass of Na2CO3.xH2O = mass conc. / molar conc.
= 5.0 / 0.0175 = 285.7 g/mol
(iii) Value of x in Na2CO3.xH2O:
285.7 = 106 + 18x
x = (285.7 - 106)/18 = 179.7 / 18 = 9.98 approximately 10

Question 2: Carry out the following exercises on specimen C and D. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test:

a.(i) Add about 5cm3 of distilled water to a portion of C in a test tube. Stir thoroughly and test with litmus.
(ii). Add about 2cm3 of Fehling’s solution to the resulting mixture from (a)(i) above and heat.
b.(i) Heat a portion of D strongly in a test tube.
(ii) Put the rest of D in a boiling tube and add about 10cm3 of distilled water. Shake the mixture.
(iii) Put about 2cm3 of the mixture from b(ii) in a test tube. Add aqueous NaOH in drops and then in excess.
(iv) Put about 2cm3 of the mixture from b(ii) in a test tube. Add aqueous ammonia in drops and then in excess.

ANSWERS FOR QUESTION 2
S/N TEST OBSERVATION INFERENCE
(a)(i) C + distilled water Soluble in distilled water C is a soluble compound
+ Litmus No effect on litmus C is a neutral compound
(ii) Solution of C + Fehling’s solution + Heat Brick-red precipitate C is a reducing sugar (glucose)
(b)(i) D + heat Yellow when hot and white when cold D is zinc oxide (ZnO)
(ii) D + water Does not dissolve in water D is an insoluble compound
(iii) Mixture from (b)(ii) + NaOH(aq) in drops and in excess White precipitate. Precipitate dissolves in excess Al3+, Zn2+, Pb2+ present
(iv) Mixture from (b)(ii) + NH3(aq) in drops and in excess White precipitate. Precipitate dissolves in excess Zn2+ Confirmed

oz4real83:
most women have an unusual kind of attraction for cars to the extent that they can easily fall in love with car owners irrespective of the car owner's personality, her former boyfriend can still win her back if he buys a car better than the one the girlfriend snatcher has

omoadeleye:
Lolz , stfu , quick to reply, retard to comprehend.

You can recognise poverty induced opinions but you are an illiterate to know the meaning of 150k dolls to 6m naira.

You be olodo
You think everyone is poor like you.
Go to property rental listings and see 500 million per annum houses. Is it not Nigerians that are paying for it ?
150k dolls is not even up to 100m.
Some people make 200m per week in this same country .
What is 150k dolls?

zicoraads:
Why would anyone build a water tank under a sitting spot or even close to it? We thank God for sparing him. However, his carelessness almost resulted to his death.

Rubbiish:
Lolzzz are u sure u are in Nigeria?
Go ask how much for bag of cement & building materials

Rubbiish:
Your analogy is wrong
6m can't get u any decent land talk more of building. You can't be comparing that to over a 110m naira.

wildikeman:
That's pounds foolish to me....una and pepper dem lifestyle no dey do una for this yeye country

lilyheaven:
It’s not their fault, it’s because someone is getting it done for them.
Many times it’s upbringing too.
Don’t touch it , don’t it.
They will grow up with fears.
My momma no send us , while we were growing up, we took care of our responsibilities, like bathing eating, wearing our clothes, etc
If you like don’t eat, nobody cares, na stream we dey go bath sef .
I started climbing trees when I was small, even coconut trees.😃
Come to plumbing work, I fix .
Small small electrical work at home, I fix them.
meanwhile , my husband who is a man that should be doing all these things , will be doing sme-sme-.

I have visited a woman once, they had power supply ooo... madam switch on TV , she said she doesn’t know how to do it, she’s waiting for her husband 🙄
I just weak for her.

Raheeqilmaktoom:
Not even at the very least the names of those states won by Mr. Obi.

Globad:
Tinubu will win this

garfield1:
Obi and atiku cases are already dead going by the recent judgment sir which upheld bvas and irev