A sample of 8.69 g of Zn(OH)2 is added to 155.0 mL of 0.750 M H2So4. (a) Write the chemical equation for the reac- tion that occurs. (b) Which is the limiting reactant in the re- action? (c) How many moles of Zn(OH)2, H2SO4, and ZnSO4 are present after the reaction is complete?

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

answersilicon (si); oxygen (o);