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