Use the table below for the next four questions.

ion [a.] symbol cu+1 atomicnumber 29 massnumber [b.] protons [c.] neutrons 34
electrons [d.]

hints:

if an ion has a + charge, that indicates it has more protons (+) than electrons this means the atom has lost electrons.
if an ion has a - charge, that indicates it has more electrons than protons (+). this means the atom has gained electrons.

[a] corresponds with:

a. copper

b. cerium

c. chromium

d. copernicium

[b] corresponds with:

a. 58.933

b. 54.938

c. 63.546

d. none of the above

[c] corresponds with:

a. 28

b. 30

c. 32

d. none of the above

[d] corresponds with:

a. 28

b. 29

c. 30

d. none of the above

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

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.