Help preparing for a wonderful chem sac :(

[rainbows.]

Hey, im going to start this new post page hoping all the smart chem loving people out there can answer all my air headed questions and solve all my chem confusion :uglystupid2:, in hope of me passing this delightful little chem sac i have on thursday :buck2:! Sorry to leech the brains off you all, but i would really really times *sides ways 8 grateful for all the help. Chem is fun in year 11 but now its so blehh >:/

Thank you all once again for helping, and please bear with me if i ask extremely stupid questions - Just like to double check things and note im just plainly an air head

So first thing i want to ask is, WHAT IS g/L ? I know its grams per liter but is it a concentration or just a unit of measure for a mass ? :/

[qshyrn]

Hey, im going to start this new post page hoping all the smart chem loving people out there can answer all my air headed questions and solve all my chem confusion :uglystupid2:, in hope of me passing this delightful little chem sac i have on thursday :buck2:! Sorry to leech the brains off you all, but i would really really times *sides ways 8 grateful for all the help. Chem is fun in year 11 but now its so blehh >:/

Thank you all once again for helping, and please bear with me if i ask extremely stupid questions - Just like to double check things and note im just plainly an air head

So first thing i want to ask is, WHAT IS g/L ? I know its grams per liter but is it a concentration or just a unit of measure for a mass ? :/

g/L is a unit for concentration (the mass of solutes in g , in how much L of solvent) it can also be written as ppm (think of 1 gram in 1 million grams, as 1 million grams is 1kg, we take it as 1 L)

[rainbows.]

Hrrm, so in other words if i have 20.0 g/L , can i write it as 20.0M ?

[qshyrn]

Hrrm, so in other words if i have 20.0 g/L , can i write it as 20.0M ?

no. 'M' or Molarity is how many mols of solute per Litre of solution. so if you have 20g/L  convert the 20g into a number of mols (n=mass/molar mass) then youve got the molarity

[superflya]

Hrrm, so in other words if i have 20.0 g/L , can i write it as 20.0M ?

nooo. 20 M is mol/L

[rainbows.]

Oh okay, hrmm, thanks.. *goes back to rub out the Ms lol....*

[m@tty]

g/L is a unit for concentration (the mass of solutes in g , in how much L of solvent) it can also be written as ppm (think of 1 gram in 1 million grams, as 1 million grams is 1kg, we take it as 1 L)

No g/L can not be written as ppm. ppm is mg/L. That's because you assume and 1000 mg = 1g and 1000g=1kg=1L. Hence, 1,000,000 mg = 1 L.

[rainbows.]

Is it okay with people, if i type up my practice sac, and ask questions about it? Or is that something werid im about to attempt to do?

And i get the g/L thing now i guess - Thanks !

[superflya]

Is it okay with people, if i type up my practice sac, and ask questions about it? Or is that something werid im about to attempt to do?

if u can be bothered, go ahead

[rainbows.]

Aim: To demonstrate the principles of colorimerty and the use of known standard solutions in QUANTITATIVE ANALYSIS by electronic equipment.

Procedure:
1. 39.34g of CuSO4.5H2O was dissolved in distilled water and made up to 500.0cm^3. This was used as a stock soultion for the standards constructed for this exercise. If Mr(CuSO4.5H2O) is 249.96 and Mr(cu)= 63.54, find the mass of Cu in the stock solution in grams per liter (g/L) and in parts per million (ppm). (Assume the density of the solution is 1.00g/cm^3)

2. The "known standards" used to construct the calibration curve were made up according the following table. Use the stock solution concentration and appropriate dilution factors to calculate the concentration of each of the standards prepared.

The standards are in blue color so we analyze with a light color which is absorbed the most. what should we use? (We have a limited choice in this case).

3. Starting with the weakest standard, put about 20ml in a clean cell and find the adsorbance reading using the appropriate light source. Rinse the cell and test all the standards.

4. Plot a neat graph of ABSORBANCE Vs CONCENTRATION

5. Run samples of UNKNOWNs through the colorimeter and record the results. Use the graph to determine the concentration of copper ions in each of them.

Okay, thats a practice PRAC SAC, and my own PRAC SAC is prob very close to this one, maybe with just a different substance or something lets hope  ><

Umm, im missing the table, but ill scan that later, and yeah i realise i could of scaned the whole sheet but i was nearly done anyways so yeah  =="

FIRST THING; i want to ask.. the weight of Cu is 10.00g ? 0.0 Yes/No? Probably no LOL 

[rainbows.]

Wait, its 20.0g right? I missed the 500ml/1000 bit in my calculation before, *hits head