Q.2. How does the valency of elements vary in going down a group of the periodic table?
1 answer:
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Answer:
T₂ = 43.46 °C
Explanation:
Given that:
The heat of the formation of carbon dioxide = - 393.5 kJ/mol (Negative sign suggests heat loss)
It means that energy released when 1 mole of carbon undergoes combustion = 393.5 kJ = 393500 J
Heat gain by water = Heat lost by the reaction
Thus,
For water:
Mass of water = 5100 g
Specific heat of water = 4.18 J/g°C
T₁ = 25 °C
T₂ = ?
Q = 393500 J
So,
T₂ = 43.46 °C
To determine the mass of an atom in terms of atomic mass unit (a.m.u.) the standard should have the fixed mass otherwise the calculated mass of the other atoms will get error. Initially oxygen was used as the reference standard for the calculation of other atoms mass. But after the invention of different isotopes of oxygen i.e. and
which ratios with respect to
is 1.002 the mass of standard oxygen became unstable. Thus the mass of the new atom have error. Thus in 1961 the standard reference is canged to carbon-12. After that onward the mass of the other atoms are measured with respect to carbon.