Given the following equation: cu + 2 agno3 → cu(no3)2 + 2 ag
how many moles of cu are needed to react with 3.50 moles of agno3?
mols

1.75 moles of copper are needed to react with 3.50 moles of AgNO₃.

Explanation:

Given data:

Moles of copper needed = ?

Moles of AgNO₃ = 3.50 mol

Solution:

Chemical equation:

Cu + 2AgNO₃  → Cu(NO₃)₂ + 2Ag

Now we will compare the moles of copper and AgNO₃.

                      AgNO₃         :            Cu

                          2               :             1

                        3.50            :             1/2×3.50 = 1.75 mol

So 1.75 moles of copper are needed to react with 3.50 moles of AgNO₃.

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