Cedrick & Astrid titrated a 10.00 mL aliquot of grapefruit juice with a 0.171 M NaOH solution to the end point. They calculated that there was 0.1698 g of citric acid present in the juice sample. What is the amount mg of citric acid present per mL of juice?

17 mg/ml.

Explanation:

Since NaOH was titrated against Citric acid in the grape fruit, therefore

Converting g to mg,

0.1698 g * 1000 mg/1 g

= 169.8 mg

Volume of grapefruit juice = 10 ml

Mass of Citric acid in ml of juice = 169.8/10

= 17 mg/ml.

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