Biết khối lượng tuyệt đối của nguyên tử natri là 38,1643.10−27 kg. Nguyên tử khối của natri (tính theo u) là giá trị nào sau đây? A. 11 u B. 22,98 u C. 12 u D. 23 u.

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

the answer is 0.42 is that is an option. this question provides no info