The following data are obtained when dinitrogen and dioxygen react together to form different compounds:
Mass of dinitrogen Mass of dioxygen
(i) 14 g 16 g
(ii) 14 g 32 g
(iii) 28 g 32 g
(iv) 28 g 80 g
(a) Which law of chemical combination is obeyed by the above experimental data?Give its statement.
(b) Fill in the blanks in the following conversions:
(i) 1 km = ...................... mm = ...................... pm
(ii) 1 mg = ...................... kg = ...................... ng
(iii) 1 mL = ...................... L = ...................... dm3
Let us fix 14 parts by weight of nitrogen as fixed weight.
Now let us calculate the weights of oxygen which combine with 14 parts by weight of nitrogen
Sno |
No of parts by weight of nitrogen |
No of parts by weight of oxygen |
14 parts of nitrogen as fixed weight |
No of parts by weight of oxygen which combine with 14 parts by weight of nitrogen |
1 |
14g |
16g |
14g |
16 |
2 |
14g |
32g |
14g |
32 |
3 |
28g |
32g |
14g |
32 |
4 |
28g |
80g |
14g |
80 |
(a) If we fix the mass of dinitrogen at 14 g, then the masses of dioxygen that will combine with the fixed mass of dinitrogen are 16 g, 32 g, 32 g, and 80 g.
The masses of dioxygen bear a whole number ratio of 1:2:2:5. Hence, the given experimental data obeys the law of multiple proportions.
This law was given by Dalton in 1804. The law states that if two elements combine to form 2 or more compound, then the weight of one element which combines a fixed weight of other element in these compounds,bears a simple whole number ratio by weight.
(b) (i) We know 1km=1000m
Or 1m = 1000 mm
Therefore 1km = 1000x 1000mm= 106 mm
1 km = 1 km ×
1 km = 1015 pm
Hence, 1 km = 106 mm = 1015 pm
(ii) We know 1kg = 1000mg
Or 1000mg= 1kg
Or 1mg= 1/1000* 1= 0.01 kg
1 mg = 1 mg ×
⇒ 1 mg = 106 ng
1 mg = 10–6 kg = 106 ng
(iii) We know 1000 ml=l L
Or 1ml=1/1000*1= 0.01L
1 mL = 1 cm3 = 1 cm3
⇒ 1 mL = 10–3 dm3
1 mL = 10–3 L = 10–3 dm3
The mass of an electron is 9.1 × 10–31 kg. If its K.E. is 3.0 × 10–25 J, calculate its wavelength.
Calculate the amount of carbon dioxide that could be produced when
(i) 1 mole of carbon is burnt in air.
(ii) 1 mole of carbon is burnt in 16 g of dioxygen.
(iii) 2 moles of carbon are burnt in 16 g of dioxygen.
Calculate the wavelength of an electron moving with a velocity of 2.05 × 107 ms–1.
Balance the following redox reactions by ion – electron method :
(a) MnO4 – (aq) + I – (aq) → MnO2 (s) + I2(s) (in basic medium)
(b) MnO4 – (aq) + SO2 (g) → Mn2+ (aq) + HSO4– (aq) (in acidic solution)
(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
(d) Cr2O7 2– + SO2(g) → Cr3+ (aq) + SO42– (aq) (in acidic solution)
In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.
(i) 300 atoms of A + 200 molecules of B
(ii) 2 mol A + 3 mol B
(iii) 100 atoms of A + 100 molecules of B
(iv) 5 mol A + 2.5 mol B
(v) 2.5 mol A + 5 mol B
At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?
Which one of the following will have largest number of atoms?
(i) 1 g Au (s)
(ii) 1 g Na (s)
(iii) 1 g Li (s)
(iv) 1 g of Cl2(g)
Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?
An alkene 'A' on ozonolysis gives a mixture of ethanal and pentan-3-one. Write structure and IUPAC name of 'A'.
Consider the reactions:
(a) H3PO2(aq) + 4 AgNO3(aq) + 2 H2O(l) → H3PO4(aq) + 4Ag(s) + 4HNO3(aq)
(b) H3PO2(aq) + 2CuSO4(aq) + 2 H2O(l) → H3PO4(aq) + 2Cu(s) + H2SO4(aq)
(c) C6H5CHO(l) + 2 [Ag (NH3)2]+(aq) + 3OH-(aq) → C6H5COO-(aq) + 2Ag(s) + 4NH3(aq) + 2 H2O(l)
(d) C6H5CHO(l) + 2Cu2+(aq) + 5OH-(aq) → No change observed.
What inference do you draw about the behaviour of Ag+and Cu2+from these reactions?
The mass of an electron is 9.1 × 10–31 kg. If its K.E. is 3.0 × 10–25 J, calculate its wavelength.
How does H2O2 behave as a bleaching agent?
Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 6800 Å. Calculate threshold frequency (v0) and work function (W0) of the metal.
Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040 (assume the density of water to be one).
What are electrophiles and nucleophiles? Explain with examples.
A 0.02 M solution of pyridinium hydrochloride has pH = 3.44. Calculate the ionization constant of pyridine
Consider the reactions :
2 S2O2– 3 (aq) + I2(s) → S4 O2– 6(aq) + 2I – (aq)
S2O2– 3(aq) + 2Br2(l) + 5 H2O(l) → 2SO2–4(aq) + 4Br–(aq) + 10H+(aq)
Why does the same reductant, thiosulphate react differently with iodine and bromine ?
Calculate the atomic mass (average) of chlorine using the following data:
% Natural Abundance | Molar Mass | |
35Cl | 75.77 | 34.9689 |
37Cl | 24.23 | 36.9659 |
Thx
No it is given in the question itself that the ratio of dioxygrn is 16, 32 , 32, 80 so the whole no ratio with dinitrogen is 1:2:2:5
If we fix the mass of dinitrogen at 14 g, then masses of dioxygen will be 16 g, 32 g, 16 g, & 40 g. Then the ratio becomes 1:2:1:2.5. Is there any mismatch or i have understood wrong. Kindly clarify With regards Krishnaraj