standard solution question (1 Viewer)

[Steven12]

the first question after multiple, i was stuck. what did you guys write?

 

[sub]

dessicate...add known NaHCO3 amount...dissolve...pour into flask...rinse beaker and stirring rod few times...and then fill to mark.

i think thats a brief correct outline...

 

[tina_goes_doo]

I said something about carefully weighing the solid on a preweighed petri dish then washing it into a 250mL volumetric flask. Add water until it's almost to the mark then add it dropwise. It was actually listed in steps in mine and i included stuff like washing the volumetric flask. How correct is this answer? I don't know i just made it up.

 

[wind]

I'd just do what sub did but put a stopper on instead of using the stirring rod.

Invert a couple times to ensure maximum dissolving of standard.

 

[lucyinthehole]

i decided that i have no brain and so proceeded to describe a titration, after saying that you need to dissolve a wieghed amount of crystals in water. so i'm looking at 1 mark for that. max so stoopid

 

[sub]

no wind...the stirrer is to mix the stuff, and since u put it in the beaker...u can use it to direct the flow of the pouring into the flask...making sure nothing is spilt...thas y i had the stirrer...i thought u guys knew...ie used the same procedure so i din elaborate

tina...u gotta rinse the beaker a few times to ensure that all the crap goes into the flask, otherwise ur concentration is off...also after filling to the mark...stopper the flask and upend it to mix thoroughly...i think thas about it...

 

[wind]

Ohhh...oops lol

My bad!

 

[sub]

no probs dude...dw tho...its over...i fuked up too, worse than u...trust me...but learning at some stage is better than not at all.

 

[tina_goes_doo]

I forgot to mention inverting it. I said something about washing the petri dish with distilled water into the flask to make sure all the solute is collected. This was after i washed the flask throughly with distilled water.

And did you guys say something about running distilled water over the stirrer when taking it out of the solution?

 

[smegthehead]

i said that the SHC is weighed on an electronic balance, then funneled into the volumetric flask, and any traces left on the funnel are washed into the flask with distilled water. the flask is then filled upto the mark, stoppered, and shaken to dissolve all the SHC. presto!

 

[danny]

Did you ahve to alk abtout the bottom meniscus mark?

 

[tina_goes_doo]

I stuck in avoid parallax but i'm not sure if that was needed.

 

[smegthehead]

I stuck in avoid parallax but i'm not sure if that was needed.

yeah it just wanted the procedure, if it wanted the ways you could ensure accuracy and whatnot i'd have written that too

 

[lucyinthehole]

wahh.. reading thorugh all this, which i knew (!) makes me so pissed off for screwing it up so stupidly!

 

[Feral]

Looks like you all forgot that a solid used to make a standard solution needs to be ANHYDROUS before it is used, usually heating it slightly will remove any moisture, oopsies for you guys

 

[sub]

mate i didn't forget... i sed to desiccate...same shit

 

[Bridget]

Haha I had no idea for this question.

"Mix it with water" was my answer!

 

[MaryTylerMoore]

I think you have to measure and excess and dry it in an oven. Then place it into a dissicator over night. Then you measure the correct amount in a beaker for the correct concentration using an electric balance. Then you dissolve it in the beaker with a squirt bottle and pour it into a clean, dry volumetric flask and rinse the beaker into the volumetric flask. Fill up to graduation, put on cap and invert to mix.

In class, we used oxalic acid because we were running low on time to finish the topic so we used an acid to know the base which could be used on an acidic substance, instead of a base, on an acid, on a base then finally on an acid. lol

 

[beverly]

I think you have to measure and excess and dry it in an oven. Then place it into a dissicator over night. Then you measure the correct amount in a beaker for the correct concentration using an electric balance. Then you dissolve it in the beaker with a squirt bottle and pour it into a clean, dry volumetric flask and rinse the beaker into the volumetric flask. Fill up to graduation, put on cap and invert to mix.

yep this is pretty much spot on. i forgot to say to invert it but i was running out of space anyway, and i had to write meniscus/parallax stuff around the next question