gen chem DAT destroyer questions

[molar3]

heylo dat'ers
i was doing destroyer, and i came across 2 probs i'm confused about, i dont know if its bc im losing my mind or if i just really dont understand but anyway ....


# 231 for gen chem--How many ml of 0.12M KOH must be added to 60ml of 0.20M HF to produce a soln with a ppH of 3.3 (pka of HF=3.3)

the answer is a........but i set the problem up like
(x)(0.12M)=(60ml)(.20M)
(x) (0.12 M)= TWELVE

12 / 0.12 ==a hundred (100) , and i would divide 100 by 2 because ur titrating a weak acid with a strong base so youd only need half the strong base.

am i CRAZY and is 60 x 0.2 not 12 .....or is it 1.2?? why is destroyer saying the answers 5 and not 50.......did i mess up?? or is this a typo? er wats going on


2nd question--#238 gen chem --Which set of quantam # best describes a valence e- in Ge?

Germanium electron config: (Ar)4s2 3d10 4p2
the answers B: 4, 1, 1, 1/2
which would be for the P valence subshell

how come S isnt counting as valence (ie-why cant the answer also be a)? because its full? i thought u just dont count D as valence when its full....but ud count s and p if theyre outside the noble gas config.

omg ive lost my mind.

thanks for reading this messs.................

---

Members don't see this ad.

 

[yafdental]

yes the first question you posted up is a typo because in the recent DAT destroyer I noticed that it was fixed and the math was done incorrectly. The answer is 50.

 

[FROGGBUSTER]

heylo dat'ers
i was doing destroyer, and i came across 2 probs i'm confused about, i dont know if its bc im losing my mind or if i just really dont understand but anyway ....


# 231 for gen chem--How many ml of 0.12M KOH must be added to 60ml of 0.20M HF to produce a soln with a ppH of 3.3 (pka of HF=3.3)

the answer is a........but i set the problem up like
(x)(0.12M)=(60ml)(.20M)
(x) (0.12 M)= TWELVE

12 / 0.12 ==a hundred (100) , and i would divide 100 by 2 because ur titrating a weak acid with a strong base so youd only need half the strong base.

am i CRAZY and is 60 x 0.2 not 12 .....or is it 1.2?? why is destroyer saying the answers 5 and not 50.......did i mess up?? or is this a typo? er wats going on


2nd question--#238 gen chem --Which set of quantam # best describes a valence e- in Ge?

Germanium electron config: (Ar)4s2 3d10 4p2
the answers B: 4, 1, 1, 1/2
which would be for the P valence subshell

how come S isnt counting as valence (ie-why cant the answer also be a)? because its full? i thought u just dont count D as valence when its full....but ud count s and p if theyre outside the noble gas config.

omg ive lost my mind.

thanks for reading this messs.................

you're right for the second one too, i asked this question 2 days ago. good job.

 

[molar3]

oh okay thanks guys!!
haha sorry about that froggbuster

 

[addis4ever]

you're right for the second one too, i asked this question 2 days ago. good job.

For the 2nd question, why can't we consider the d subshell as a valence e- when writing down the set of quantum numbers? is it because the d subshell is full? What if its not full? if we were given an element, say...from one of the transition elements and were asked to write out the set of quantum numbers. How would you write it down considering u have to account for the d and p subshells?

 

[molar3]

For the 2nd question, why can't we consider the d subshell as a valence e- when writing down the set of quantum numbers? is it because the d subshell is full? What if its not full? if we were given an element, say...from one of the transition elements and were asked to write out the set of quantum numbers. How would you write it down considering u have to account for the d and p subshells?

theres some rule that says for transition elements if the d subshells filled, theyre not considered valance. im not positive why, hopefully someone else can tell u that
if the d subshell is not full, then u can count the d electrons as valence.
i also think generaly, anything outside the noble gas configuration is consdiered valence bc those are the electroncs thatll be reacting to make bonds or w/e

 

[addis4ever]

theres some rule that says for transition elements if the d subshells filled, theyre not considered valance. im not positive why, hopefully someone else can tell u that
if the d subshell is not full, then u can count the d electrons as valence.
i also think generaly, anything outside the noble gas configuration is consdiered valence bc those are the electroncs thatll be reacting to make bonds or w/e

Oh ok! gotcha! i understand now, thanx.