[Hyperion]

I need help with this big *** chem prac thing... * FORMATIVE Prac #3 EXPERIMENT 4 is the one I need help with
This is the link to the document http://oac.janison.com/Training/DK_Chemi...

Someone please help, this is so confusing and I don't get it... From page 7 to page page 9..
Someone please help

[Alpha-Omega]

I need help with this big *** chem prac thing... * FORMATIVE Prac #3 EXPERIMENT 4 is the one I need help withThis is the link to the document http://oac.janison.com/Training/DK_Chemi...

The link does not work 

[Hyperion]

Try this one then. I attached the file straight from my comp this time.

[Alpha-Omega]

OK...This is a Lab Practical.  Excactly what kind of help are you seeking with regard to a practicum?  Please elaborate.  I can see all the instructions are clearly outlined.  This has to be performed in situ.  Practicums are usually timed.

The results are all based on your direct observations.  So what kind of help are you seeking?  I mean you cannot make up answers for a practicum that has not been performed.  The data cannot be manufactured out of thin air.  So is it the instructions you do not understand. Help me out here....please!!!!!

[Hyperion]

Sorry about that.
I have filled in the results I have so far but I don't get the questions...

[Alpha-Omega]

Like Part I:

REPORT    (not a complete report – report on the following )
Observations:
•   Describe any observed colour changes and present them in table form
Conclusion:
•   Explain the emission of colours
•   Explain the characteristic colours of the metals

When metals are heated, their outer electrons become excited and jump up to higher energy levels. These energized electrons are not stable at higher energy levels so they fall back down to their normal energy level, giving off their extra energy as light. As a result, metals impart characteristic colors to a flame.

So what is this process called?  You have to explain the process....here is a link that will help you understand emission:

http://www.unit5.org/christjs/flame%20tests.htm

[Hyperion]

Thanks but I know that one. I need help with the Formative Prac 3   Experiment 4 one... I have posted an updated file with my results that I have for that prac but I don't know how to do the qurstions

[Alpha-Omega]

Part 2:

Equations:
Where reactions did occur, write full equations for the reactions of the oxides:
   With water
   With acid
   With base
Conclusion:   Describe how the nature of the oxide alters across the periodic table.
      Describe how the nature of the element alters across the periodic table

You have to write out the reaction of your species with:  water, acid, and base

Reactant Species( CaO, MgO, Al₂O₃, CO₂) + water -----> Product

Reactant Species( CaO, MgO, Al₂O₃, CO₂) +  acid -----> Product

Reactant Species( CaO, MgO, Al₂O₃, CO₂) + base -----> Product

Conclusion:  What trends/differences/similarities do you observe as you go from the alkai earths to aluminum across the periodic table...what did you see....how do the elemnts cahnge across the periodic table.....your data will help you make this determination.

[Alpha-Omega]

Part 3:  Is a tiration.  You are determining the acid content in vinigar.

The balanced reaction equation is given.  Species react mole to mole (keep that in mind). Once you determine the concentration (molarity) of the diluted vinegar solution using the concentration of NaOH you have to back calculate using the 30 mL to determine the original concentration of the undiluted vinegar.  Hint:  M₁V₁ = M₂V₂.

Strategy:

Figure out how many moles of the titrant (in this case, the base) were needed.


Use the balanced chemical equation to calculate the moles of analyte (in this case, the acid) present.


Use the volume of analyte to find the concentration of the analyte.

[Gerard]

The balanced reaction equation is given.  Species react mole to mole (keep that in mind). Once you determine the concentration (molarity) of the diluted vinegar solution using the concentration of NaOH you have to back calculate using the 30 mL to determine the original concentration of the undiluted vinegar.  Hint:  M1V1 = M2V2.

Strategy:

Figure out how many moles of the titrant (in this case, the base) were needed.

-i agree with the M1V1=M2V2, but i think we should take note vinegar is an organic acid, a weak organic acid.....the equation M1V1=M2V2 might only work for strong inorganic acids,remember the concept that not all of the molecules of weak organic acids react to the base that it is mixed with,,,,

[Borek]

i agree with the M1V1=M2V2, but i think we should take note vinegar is an organic acid, a weak organic acid.....the equation M1V1=M2V2 might only work for strong inorganic acids,remember the concept that not all of the molecules of weak organic acids react to the base that it is mixed with,,,,

No such concept as far as I am aware. Weak acids may not dissociate completely, their salts may hydrolize, but when properly titrated they react stoichiometrically with strong bases and titration gives prefectly correct results.