2. one reason a standard solution of naoh cannot be prepared from solid naoh is that solid naoh is
hygroscopic: it absorbs water vapor from the atmosphere. assuming you calculated the concentration of
a naoh solution by measuring the mass of a solid sample of naoh and dissolving it in water, how
would this property of naoh affect (e. g. increase, decrease, no change) the following steps in a titration?
justify your choice.
a. the concentration of a naoh solution made from solid naoh that absorbed a significant amount of
water prior to measuring its mass.
b. the volume of the resulting prepared naoh solution needed to titrate an acid.

the ratio of the conjugate base to the acid required to attain the desired ph.

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