Question and Answer For Chemistry Problems

1) 19.2 grams of Cu(s) reacts with nitric acid solution as equation as follows :



How many volume of gases which is resulted in

(Ar Cu= 64; C= 12; H=1)

ans :

Mol Cu = 19.2 grams : 62 gram/moles = 0.3097 moles

Mol = (2/3) x 0.3097 moles = 0.2064 moles

in it means STP condition so

Volume in STP condition = 0.2064 moles x 22.4 L/moles = 4.62 L

2) In titration of 10 mL with NaOH 0.1 M, we get the concentration of 0.2 M. How many volume of NaOH needed?

ans :

mol = 10 mL x 0.2 mmol/mL = 2 mmol

mol NaOH = 2 x 2 mmol = 4 mmol

so volume NaOH = 4 mmol : 0.1 mmol/mL = 40 mL

3) We can make Hydrogen gas by using this following reaction :

with Ar of Al = 27 g/moles, so How many of grams Al which is needed to form Hydrogen 44.8 L in STP condition?

ans :

Mol Hydrogen = 44.8 L : 22.4 L/moles = 2 moles

Mol Al = (2/3) x 2 moles = 1.333 moles

Grams of Al = 1.333 moles x 27 g/moles = 36 grams

Solubility Product Constant

What is Constant Of Solubility Product??

Compounds that not easy to soluble in water, ionization of compound itself is an equilibrium reaction, it means rate of reaction between soluble and not soluble in equilibrium condition.
For example AgCl :



Not only AgCl having but also others such as bellow table having the

Table of Solubility Product Constants (K_sp at 25^o C)

Bromides	PbBr2	6.3 x 10-6
	AgBr	3.3 x 10-13
Carbonates	BaCO3	8.1 x 10-9
	CaCO3	3.8 x 10-9
	CoCO3	8.0 x 10-13
	CuCO3	2.5 x 10-10
	FeCO3	3.5 x 10-11
	PbCO3	1.5 x 10-13
	MgCO3	4.0 x 10-5
	MnCO3	1.8 x 10-11
	NiCO3	6.6 x 10-9
	Ag2CO3	8.1 x 10-12
	ZnCO3	1.5 x 10-11
Chlorides	PbCl2	1.7 x 10-5
	AgCl	1.8 x 10-10
Chromates	BaCrO4	2.0 x 10-10
	CaCrO4	7.1 x 10-4
	PbCrO4	1.8 x 10-14
	Ag2CrO4	9.0 x 10-12
Cyanides	Ni(CN)2	3.0 x 10-23
	AgCN	1.2 x 10-16
	Zn(CN)2	8.0 x 10-12
Fluorides	BaF2	1.7 x 10-6
	CaF2	3.9 x 10-11
	PbF2	3.7 x 10-8
	MgF2	6.4 x 10-9
Hydroxides	AgOH	2.0 x 10-8
	Al(OH)3	1.9 x 10-33
	Ca(OH)2	7.9 x 10-6
	Cr(OH)3	6.7 x 10-31
	Co(OH)2	2.5 x 10-16
	Cu(OH)2	1.6 x 10-19
	Fe(OH)2	7.9 x 10-15
	Fe(OH)3	6.3 x 10-38
	Pb(OH)2	2.8 x 10-16
	Mg(OH)2	1.5 x 10-11
	Mn(OH)2	4.6 x 10-14
	Ni(OH)2	2.8 x 10-16
	Zn(OH)2	4.5 x 10-17
Iodides	PbI2	8.7 x 10-9
	AgI	1.5 x 10-16
Oxalates	BaC2O4	1.1 x 10-7
	CaC2O4	2.3 x 10-9
	MgC2O4	8.6 x 10-5
Phosphates	AlP04	1.3 x 10-20
	Ba3(P04)2	1.3 x 10-29
	Ca3(P04)2	1.0 x 10-25
	CrP04	2.4 x 10-23
	Pb3(P04)2	3.0 x 10-44
	Ag3P04	1.3 x 10-20
	Zn3(P04)2	9.1 x 10-33
Sulfates	BaS04	1.1 x 10-10
	CaS04	2.4 x 10-5
	PbS04	1.8 x 10-8
	Ag2S04	1.7 x 10-5
Sulfides	CaS	8 x 10-6
	CoS	5.9 x 10-21
	CuS	7.9 x 10-37
	FeS	4.9 x 10-18
	Fe2S3	1.4 x 10-88
	PbS	3.2 x 10-28
	MnS	5.1 x 10-15
	NiS	3.0 x 10-21
	Ag2S	1.0 x 10-49
	ZnS	2.0 x 10-25
Sulfites	BaS03	8.0 x 10-7
	CaS03	1.3 x 10-8
	Ag2S03	1.5 x 10-14

ADSORPSI Ag(I) DAN Ni(II) PADA HIBRIDA AMINO-SILIKA DARI ABU SEKAM PADI

ADSORPSI Ag(I) DAN Ni(II) PADA HIBRIDA AMINO SILIKA DARI ABU SEKAM PADI

Oleh :

Moehlis Bassir

02/156470/PA/08829

Dalam penelitian ini telah dipelajari pembuatan adsorben hibrida amino silika (HAS) untuk adsorpsi ion logam Ag(I) dan Ni(II) dari abu sekam padi.

Penelitian ini diawali dengan pembuatan natrium silikat dari abu sekam padi dengan larutan 4 M NaOH. Pembuatan adsorben hibrida amino silika melalui proses sol-gel dilakukan dengan menambahkan larutan HCl 3 M ke dalam campuran larutan (3-aminopropil)-trimetoksisilan (APS) dan natrium silikat sampai pH 7. Adsoben yang dihasilkan dikarakterisasi dengan difraktometri sinar-X (XRD), spektroskopi inframerah (FTIR), dan analisis luas permukaan (SAA). Adsorpsi Ag(I) dan Ni(II) dilakukan dengan sistem batch selama 60 menit dengan variasi konsentrasi ion logam. Ion logam yang teradsorpsi dihitung dari selisih konsentrasi sebelum dan sesudah adsorpsi yang dianalisis dengan AAS. Data yang dihasilkan, digunakan untuk menentukan parameter termodinamika dengan model isotherm adsorpsi Langmuir.

Hasil karakterisasi dengan FTIR menunjukkan bahwa HAS telah dapat disintesis dengan ditunjukkan oleh munculnya serapan inframerah dari gugus fungsional silanol (Si-OH), siloksan (Si-O-Si), amin (-NH₂) dan metilen (-CH₂-). Dari data XRD diketahui bahwa HAS yang didapat berstruktur amorf. Hasil SAA menunjukkan bahwa hibridisasi menurunkan luas permukaan spesifik dan volume total pori HAS, tetapi tidak mempengaruhi diameter porinya. Hasil kajian adsorpsi Ag(I) dan Ni(II) menunjukkan bahwa penambahan senyawa APS lebih banyak pada hibridisasi menurunkan kapasitas adsorpsi, tetapi meningkatkan energi adsorpsi Ag(I), sedangkan kapasitas adsorpsi dan energi adsorpsi Ni(II) meningkat. Berdasarkan energi total yang menyertai adsorpsi, maka interaksi antara adsorben dan ion Ag(I) terjadi melalui kemisorpsi sedangkan ion Ni(II) terjadi melalui fisisorpsi.

Acid Base Reaction

To answer question from someone regarding Acid Base Reaction.
What is Acid and Base?

1. Regarding Arrhenius

An acid is a substance that increases the H+ (or H3O+) concentration in an aqueous solution.

A base is a substance that increases the

concentration in an aqueous solution.

2. Regarding Bronsted-lowry

HCl(aq) + NaOH(aq) → HOH + NaCl

Acid = a proton donor in a reaction

Base = a proton acceptor in a reaction

3. Regarding Lewis

An acid is an electron pair acceptor

Base is an electron pair donor

Acid/Base reaction : always produce water and salt.

For example :

Stochiochemistry of Chemical Reaction

What's the meaning of stochiochemistry?

Stochiochemistry deals with scale of atoms of elements in chemical formulation of elements, example scale atoms of C and O in molecule CO₂. Stochiochemistry also deals with chemical formulation of chemical equation. Basics of stochiochemistry also concern of chemical equation and mole concepts.

What's chemical reaction?

Chemical reaction deals with chemical changing between A reacted with B. Example CO_{2, has resulted from reaction of atom C (solids) with} O_{2 (gas) to be resulted} CO<sub>2 (gas). There are many kinds of chemical reactions, they are :

1. Acid Base Reaction
2. Redox Reaction
3. Polymerize reaction
4. Complexometric reaction
5. etc

From those are chemical reactions, the keys that should we hold is Stochiochemistry. Stochiochemistry deals with chemical equation and mole concepts.


Example :</sub>



How many volume of HCl 0.05 M that's needed to be reacted 2,4 g Mg (Ar Mg = 24 g/mol)?

By using stochiochemistry,

1. we have to decide the correct chemical equation to be :



2. By using mole concepts we find the volume of HCl which is needed :

mole Mg = 2,4 grams : 24 grams/moles = o.1 moles

mole Mg ~ 2 moles HCl = 0.2 moles

Volume HCl = 0.2 moles : 0.05 moles/L = 4 L

So, It needs 4 L of HCl 0.05 M to be reacted with 2,4 grams of Mg.