The compound trimethylamine, (CH3)3N, is a weak base when dissolved in water. Write the Kb expression for the weak base equilibrium that occurs in an aqueous solution of trimethylamine: Kb

Kb = [OH⁻] . [C₃H₉NH⁺] / [ C₃H₉N ]

Explanation:

The equation for the reaction of trimethylamine when it is dissolved in water is:

C₃H₉N  +  H₂O ⇄ C₃H₉NH⁺ + OH⁻   Kb

1 mol of trimethylamine catches a proton from the water in order to produce trimethylamonium.

It is a base, because it give OH⁻ to the medium

Expression for Kb (Molar concentration)

Kb = [OH⁻] . [C₃H₉NH⁺] / [ C₃H₉N ]

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol