1.

When 5.0 mL of a 1.0 M HCl solution is mixed with 5.0 mL of a 0.1 M NaOH solution, temperature of solution is increased by 2^@C predicted accurately from this observation?

Answer»

If 10 mL of same HCl is mixed with 10 mL of same NaOH, temperature rise will be `4^@C`
If 10 mL of 0.05 HCl is mixed with 10 mL of 0.05 M NaCl the temperature rise will be `2^@C`
If 5 mL of 0.1 M HCl is mixed with 5 mL of 0.1 M `NH_3` solution, the temperature rise will be lessthan `2^@C`
If 5 mL 0.1 Mis mixed with 5 mL of 0.1 M NaOH, the temperature rise will be lessthan `2^@C`

Solution :Heat involved during the neutralisation `=(1.0 xx 1 xx 10^(-3)) xx c xx 2 = 0.02 c`
0.02c heat is evolved due to the neutralization or formulation of `(0.1 xx 5) = 0.5 m` moles of `H_2O` .
(A) Heat evolved `= 0.04c= (20 xx 1 xx 10^(-3)) xx c xx DELTA T implies Delta T implies DeltaT = 2^@C [0.1 xx 10 = 1`m moles of `H_2O`formed]
(B) No temperature rise as there is no neutralization
(C) M moles offormedbut heat evolved will be less than 0.04c as is a weakbase.
(D) SIMILAR to (C). [`CH_3COOH` is a weak ACID]


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