Q17 (1 Viewer)

[Tmer]

please help me solve it;
you had:
HCl
sodium carbonate
barium nitrate
lead nitrate

this is what i did in the exam but i got confused:
1+2= gas released (HCl and sodium carbonate, first thought)

2+4= no reaction
now from my first thought, 2 is either the acid or the carbonate...
barium nitrate + HCl gives no reaction so its possible
and now (1=sodium carbonate, 2= acid, 4=barium, only thing left is 3, = lead)

but...
3+4 = white precipitate? lead nitrate and barium nitrate definitely do not react...

this is probably all wrong now... any1 confident with their answer?

 

[Forbidden.]

You may be correct.
To my shock I switched solution 1 & 2 around.

 

[Regulardelivery]

1. sodium carbonate
2. hcl
3. lead nitrate
4. barium nitrate

 

[Shrikar]

1. sodium carbonate
2. hcl
3. lead nitrate
4. barium nitrate

That's what I had.

I think the equation of solution one and solution two was

2HCL + Na2CO3 --> 2NaCl + CO2 + H2O

 

[treb0r]

Why not HCL first haha dood uve chosen same courses as me, hope to see u next year

 

[airbag]

please help me solve it;
you had:
HCl
sodium carbonate
barium nitrate
lead nitrate

this is what i did in the exam but i got confused:
1+2= gas released (HCl and sodium carbonate, first thought)

2+4= no reaction
now from my first thought, 2 is either the acid or the carbonate...
barium nitrate + HCl gives no reaction so its possible
and now (1=sodium carbonate, 2= acid, 4=barium, only thing left is 3, = lead)

but...
3+4 = white precipitate? lead nitrate and barium nitrate definitely do not react...

this is probably all wrong now... any1 confident with their answer?

There wasn't a reaction between lead and barium nitrate listed

I figured an order of Sodium carbonate, HCL, Lead Nitrate then Barium Nitrate

I'm pretty sure it's right

 

[Unwant3d]

That's what I had.

I think the equation of solution one and solution two was

2HCL + Na2CO3 --> 2NaCl + CO2 + H2O

thats exactly what i had and had my acids/bases in that order
though i did but down their states ie. aq, s, l

would you get penalised if you didnt?

 

[k4t5UM0t0]

1. Sodium Carbonate
2. HCl
3. Lead nitrate
4. Barium nitrate

1. Is sodium carbonate because all PbCO3 and BaCO3 give precipitates
2. HCl because only reaction with 1. to give bubbles (CO2)
3. Pb(NO3)2 because lead reacts with the HCl to produce a white precipitate. Ba(NO3)2 does not yield a white precipitate
4. Ba(NO3)2 last one left

 

[k4t5UM0t0]

Yes you probably will be penalised for forgetting to put in states- but really depends on marking criteria

 

[Unwant3d]

oh dear, thank god i put them in yAy!!

 

[Tmer]

mmm... im pretty sure there was a listing with 3+4... if not, then that order makes sense....

 

[Shrikar]

thats exactly what i had and had my acids/bases in that order
though i did but down their states ie. aq, s, l

would you get penalised if you didnt?

Ah, I think it was a 2 marker, so I think you would if you didn't. But yeah, i put in the states as well.

Why not HCL first haha dood uve chosen same courses as me, hope to see u next year

Are you talking about me? If so I hope to see you next year too.

 

[Unwant3d]

Ah, I think it was a 2 marker, so I think you would if you didn't. But yeah, i put in the states as well.

um i think the
"write a balanced equation for result obersvation 1"
was a one mark question

 

[Shrikar]

um i think the
"write a balanced equation for result obersvation 1"
was a one mark question

Well, there you go.

 

[Armenikum]

thats exactly what i had and had my acids/bases in that order
though i did but down their states ie. aq, s, l

would you get penalised if you didnt?

Wasnt it a ONE marker? If so, I dont think they would penalise you.

 

[jacksdharma]

#1 Sodium Carbonate
#2 HCl
#3 Lead Nitrate
#4 Barium Nitrate

All you had to know was the Sodium Carbonate and HCl made the CO2 bubbles
All Group 1 Nitrates are Soluble (therefore Barium = no reaction)
Lead Nitrate forms a precipitate

So from those properties you can deduce and eliminate the substances

 

[Unwant3d]

i think we can comfortably say, we've worked out the answer in the correct order.
haha

what did everyone write about "why it wasnt suitable for a flame test"

i wrote:
due to the presence of lead, it would be unstuable, since when lead is vapourised it produces a toxic gas, and the lead solution was unknown thus would be unsafe and unsuitable for a flame test

*fingers crossed* this is ok =/

 

[dacomens]

omg i thought this was the hardest friken question in the whole exam...it took too long to try and figure out shit! there goes a precious 5 marks...BOS bastards

 

[Shrikar]

i think we can comfortably say, we've worked out the answer in the correct order.
haha

what did everyone write about "why it wasnt suitable for a flame test"

i wrote:
due to the presence of lead, it would be unstuable, since when lead is vapourised it produces a toxic gas, and the lead solution was unknown thus would be unsafe and unsuitable for a flame test

*fingers crossed* this is ok =/

I said that when some atoms absorb energy and emit light, the light isn't always visible, (that is why AAS is used), thus it would be inappropriate to use a flame test.

I remember reading it in a book somewhere.

 

[ajdlinux]

I got HCl and Na2CO3 mixed up, if the answers here are correct. Oh well, hopefully I can get one of the two (yes, I'm sure it was two) marks for hopefully getting the Ba and Pb compounds in the right order.