Find the number of phosphates in
In 3.44 moles of phosphorus.

2.07 x 10 24  atoms of P

Explanation:To find the number of atoms in the given moles of the element follow the following steps:

Step 1 : Use the avogadro number to convert the moles to atoms.We know that 1 mole of any atom ,compound,formula unit has 6.02 x 1023 atom,compound or formula unit .In the problem given here there are  3.44 moles of P atom .

1 mole of P atom = 6.02 x 1023 atoms of P

Step 2 : How many atoms will be in 3.44 moles of phosphorus.Use the formula

Given x conversion factor

(given is the condition given in the problem and A conversion factor is a ratio (or fraction) which represents the relationship between two different units) .

3.44 moles of P x 6 .02 x 1023 atoms of P / 1 mole of P atoms = 2.07 x 10 24  atoms of P

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