Question

Which statement is most likely to be true for astatine, which is below iodine in Group VII of the
Periodic Table?
A Astatine and aqueous potassium chloride react to form aqueous potassium astatide and
chlorine.
B Potassium astatide and hot dilute sulphuric acid react to form white fumes of only hydrogen
astatide.
C Silver astatide reacts with dilute aqueous ammonia in excess to form a solution of a soluble
complex.
D Sodium astatide and hot concentrated sulphuric acid react to form astatine.

Answer 1

can anyone explain why is it not A or B or C but its D
is there any reasoning behind it or is it just pure memorization?

Answer 2

@Kainui

Answer 3

@chmvijay @aaronq @emcrazy14

Answer 4

@iPwnBunnies

Answer 5

It should be:
because SO4^-2 (sulfate ion) is strong reducing agent as compared to Astatine so, sulfate ion reacts with Na by replacing Astatide. for confirmation u can check reduction potential of Sulfate and Astatide. the specie having greater reduction potential will reduce itself and oxidizes the other

Answer 6

emmm i don't know if i got it but i don't why why not others? @waxynaveed @Kainui @chmvijay @aaronq @emcrazy14 pleeeease help T_T

Answer 7

D Sodium astatide and hot concentrated sulphuric acid react to form astatine.

:) Sorry for the long wait, just got on.

Answer 8

@somy Let me help you out, if you have other questions.

Answer 9

@alphadxg thnx but i know the answer...
i just need reasoning why is it not others but D

Answer 10

@Somy Correct, you need to understand how these reactions are happening, you have to know your solubility rules (I know they are a pain) Need to know your lewis acids and bases, bronsted acid and bases and how they are used in a reaction. Those are the key things, so yes in a way you do have to understand them to see what the end result is, you will have to write them out to get a better picture (That's what I do).

Answer 11

And as far as a question like this goes, you just have to memorize it, unless you are PhD in a field.

Answer 12

yeah i know that's what i do too, i can not memorize stuff like that without understanding, even if i do i'll forget it in blink of an eye, but if i understand it i'll never forget..

Answer 13

ughhh how sad T_T

Answer 14

@Somy : You just need to understand first that Astatine is an element which is at the end of Group 7 in the Periodic Table and thus; compare its properties with the elements above it.

You do know that reactivity decreases down Group 7 so in a reaction mixture, any element above another will displace it from a solution of its salt. So A is incorrect since Astatine will be least reactive and thus cannot displace chloride ions to form chlorine.

B is incorrect since you know that oxidising ability of halogens decreases down the group. You would know that dilute H2SO4 is a strong enough oxidising agent to oxidise Br- ions to bromine gas, so it must also be able to oxidise astatide ions to form solid astatine.

For reaction with aq. NH3, you do know that precipitates are formed but the solubility of these precipitates in excess ammonia decreases down the group. Like AgCl is soluble in dilute and concentrated NH3, AgBr is soluble only in concentrated NH3, and AgI is insoluble in both dilute and concentrated NH3. Silver astatide will therefore also be insoluble in NH3. Thus, C is also incorrect.

Answer 15

@emcrazy14 THANK YOUUUUU!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! <333333

Answer 16

finally!!!!! omg really thank u sooooooooooo much!!!!

Answer 17

@emcrazy14 :*

Answer 18

@emcrazy14 really...thanks a lottttttt

Answer 19

No problem, guys! :)