Opinion? Theory? Are there options for the answer? Generally scientists are sure to keep their findings un-biased, so keeping their own personal opinions or feelings out of the research is essential. They WOULD base their knowledge on facts and Scientific Theory which is slightly different then general theory.
With an atomic number of 55, that means there are 55 protons. Because electrons do not count towards atomic weight, the element would have 150-55 neutrons. So, 95 neutrons.
NH3(aq) + HCl(aq) ⇒ NH4Cl(aq) >>> (1)
∵ C = n/V; C= concentration, n= No. of moles, and V= volume (L)
∴ n = C*V, n(HCl) = 0.050*(50/1000) = 0.0025 moles
n(NH3) = 0.050*(50/1000) = 0.0025 moles
So, the limiting no. of moles is 0.0025 moles >>> (2)
∵ NH3 is weak base, and HCl is strong Acid (and have the same number of moles) >>> So, without any calculation we can notice that the formed salt (NH4Cl) is acidic salt and the pH is less than 7.
From (1) and (2), The no. of moles of NH4Cl is 0.0025 moles >>> (3)
∴ the concentration of [NH4Cl] = 0.0025 / (total volume per L)
= 0.0025 / ((50 + 50) / 1000) = 0.025 M
NH4+(aq) ⇔ NH3(aq) + H+(aq) >>> (4)
(0.025 - x) (x) (x) >>> (5)
∵ Ka = [NH3] [H+] / [NH4+] >>>> (6)
Ka = Kw / Kb, Kb = 1.8 * 10^-5 >>> (7)
∴ Ka = 10^-14 / 1.8*10^-5 = 5.56*10^-10 >>> (8)
From (4), (5), (7) and (8)
Ka = 5.56*10^-10 = (x * x) / (0.025-x) , we will assume that (0.025 - x) = 0.025
∴ x^2 = (5.56*10^-10)(0.025) = 139*10^-13
∴ x = 3.73*10^-6 = [H+]
∵ pH = - log [H+]
∴ pH = - log 3.73*10^-6 = 5.43
The process of chemical weathering by oxygen and water on iron is known as rusting........rust is a loose reddish brown layer of hydrated ferric oxide(Fe2O3.H2O)
<h3>Exothermic reactions
</h3>
These are reactions that transfer energy to the surroundings (ie the energy exits from the reaction, hence the name exothermic). The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become hotter. A thermometer is used to detect the temperature increase.
Examples:
Combustion
Neutralisation between acids and alkali
<h3>Endothermic reactions
</h3>
These are reactions that take in energy from the surroundings (ie energy enters the reaction, which will help you to remember the name endothermic). The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become colder. A thermometer is used to detect the temperature decrease.
Example:
Electrolysis