Net ionic equations

  • Thread starter joejo
  • Start date
  • #1
150
0
hi, i'm studying for the chemistry SAT and have a question that I'm not sure that ive done right...can someone please check my answer...thanks in advance!

Write a net ionic equation for the following:

a) Chromium dipped into silver nitrate
b) Aluminmum dropped into a bath of sulphuric acid
c) Zinc dipped into a solution of led (II) nitrate

answers:

a) Cr(s) + Ag+ (aq) --> Cr2+ (aq) + 2Ag (s)
b) d)Al3+ + H2SO4 --> Al2(So4)3 + H2
c) Zn2+ + Pb(NO3)2 --> Zn(NO3)2 + Pb2+

im not sure if I have to have the (s), (aq) etc....

can someone correct my answers if they are wrong...

thanks again
 

Answers and Replies

  • #2
1,100
0
A looks right. You have state symbols missing from B and in an ionic equation the hydrogen ions are not changing so are not needed (I believe). C also has no symbols and again the lead is not really changing for an ionic equation.

The Bob (2004 ©)
 
  • #3
150
0
my friend helped me get a...the answers for b and c are mine...I still dont get it...can you please show me?
 
  • #4
150
0
someone please my test is on thursday i need to study!! Thanks guys
 
  • #5
dextercioby
Science Advisor
Homework Helper
Insights Author
13,077
645
[tex] 2\mbox{Al}_{(\mbox{s})}+6\mbox{H}^{+}_{(\mbox{aq})} \rightarrow 2\mbox{Al}^{3+}_{(\mbox{aq})}+3\mbox{H}_{2}\uparrow [/tex]

(sulphate ions are spectators)

[tex] \mbox{Zn}_{(\mbox{s})}+\mbox{Pb}^{2+}_{(\mbox{aq})}\rightarrow \mbox{Zn}^{2+}_{(\mbox{aq})} +\mbox{Pb}\downarrow [/tex]

(nitrate ions are spectators)


Daniel.
 
  • #6
dextercioby
Science Advisor
Homework Helper
Insights Author
13,077
645
And the first one needs another 2.It should read

[tex] \mbox{Cr}_{(\mbox{s})}+2\mbox{Ag}^{+}_{(\mbox{aq})}\rightarrow \mbox{Cr}^{2+}_{(\mbox{aq})}+2\mbox{Ag}\downarrow [/tex]

(Nitrate ions are spectators)


Daniel.
 
  • #7
2,209
1
b. aluminum into sulfuric acid
If I remember how to do these correctly:
[tex] 2Al + 3H_2SO_4 \rightarrow Al_2(SO_4)_3 + 3H_2 [/tex]

Break it down into its compounds:

[tex] 2Al + 3H_2^+ + 3SO_4^{2-} \rightarrow Al_2^{3+} + (SO_4)_3^{2-} + 3H_2 [/tex]

Look on both sides to see if anything is idle during the process. It looks like everythings reacting, even the hydrogens look like theyre doing something, since they go from [itex] H_2^+ \rightarrow H_2 [/itex].

I would go to http://www.towson.edu/~ladon/netionic.html for some more help.

edit: Sulfate is spectating as dex said, i didnt see the coefficient. Cros it out
 
  • #8
dextercioby
Science Advisor
Homework Helper
Insights Author
13,077
645
The net charge in your equation,in the form written,doesn't add to zero in any of the 2 members,though it should...U have 6 protons from 3 sulphuric acid molecules...They're not 3 molecule-ion of Hydrogen...They have total charge "6+",and not "3+" as your notation would assume...

Daniel.
 
  • #9
2,209
1
So in this case you would write H as a single atom and not a diatomic? theyre teaching us to always write the diatomics as diatomics. My notation is probably unorthodox but when I counted it it added up right.

[tex] 2Al + 3H_2^+ + 3SO_4^{2-} \rightarrow Al_2^{3+} + (SO_4)_3^{2-} + 3H_2 [/tex]

Left:
2Al = 0
3H_2 += +6
3SO_4 2- = -6

Right:
Al_2 3+= 6+
SO_4 _3 2- = 6-
H_2 = 0
 
  • #10
dextercioby
Science Advisor
Homework Helper
Insights Author
13,077
645
That is not diatomic (in the LHS),it's simply 2 [itex] \mbox{H}^{+} [/itex] ions (protons) involved in a chemical bound (covalent,but here we're interested in ionic reactions,though the chemical bounds are not necessarily ionic) with 2 atoms of oxygen from the 4 involved in the sulphate ion...

Notation is essential only when it's wrong.

Daniel.
 
  • #11
2,209
1
Ok I see where I went wrong, thanks. Learn from my mistakes joejo :)
 
  • #12
150
0
no u've totally lost me whos right...whozum or dexter...

dexter your right, right??
 
  • #13
dextercioby
Science Advisor
Homework Helper
Insights Author
13,077
645
>50% of the time,this one included :wink:

Daniel.
 
  • #14
150
0
thanks guys...


i dont get u dexter...are you saying ur guessing?
 
  • #15
2,209
1
dexters always right.
he has a phd in everything.
 
  • #16
150
0
thank alot guys
 

Related Threads on Net ionic equations

  • Last Post
Replies
0
Views
6K
V
  • Last Post
Replies
8
Views
37K
Replies
1
Views
14K
V
Replies
1
Views
5K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
6
Views
1K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
8
Views
30K
R
  • Last Post
Replies
1
Views
11K
  • Last Post
Replies
1
Views
6K
Top