Moles are used conveniently in chemistry especially in stoichiometric calculations involving reactions. The unit of mole is a collective term that holds 6.022×10^23 particles. These particles is a general term for any small units of matter including molecules, atoms and sub-particles. This ratio of 6.022×10^23 particles to 1 mole is known to be the Avogadro's number. Its exact number is actually <span>6.0221409</span>×10^23. We use this constant in our stoichiometric calculation as follows:
15 moles oxygen * (6.022×10^23 molecules/ 1 mole oxygen) = 9.033×10^24 molecules of oxygen
As we know,
pH + pOH = 14
Or,
pOH = 14 - pH
Putting Value of pH,
pOH = 14 - 10.62
pOH = 3.38
pOH is converted into [OH⁻] as follow,
[OH⁻] = 10⁻pOH ∴ -pOH is in power, 10 means antilog
press shift and click log button
[OH⁻] = 10⁻³°³⁸
[OH⁻] = 0.0004168
[OH⁻] = 4.16 × 10⁻⁴
Aluminium belongs to 13th group of periodic table. It undergoes oxidation to given Al^+3 .
It is observed that when aluminium is added to a solution of copper sulphate the colour of the solution changes from blue to grey. It is due to formation of grey coloured solution of aluminium sulphate as
2Al^+3 + 3SO4^-2 ---> Al2(SO4)3
23.0 + 60.0 = 83.0° C heat energy is required to raise
