[NewbieScience66]

Hi,
I am new to Chemistry and I having a hard time trying to figure out these calculations. Ive been reading on how do this but I'm lost. I know how to find moles, percent composition, theorectical yeild but I'm lost on this. Any help will be greatly appreciated.... I know 875 uls is equal to .875 ml. I dont' know how to set up the intial problem...

a. 2-propanol (60.10g/mol) has a density of 0.785 g/ml.  Calculate the mg in 825 uLs of 2-propanol.; Calculate the moles of 2-propanol in 825 uLs.   

b.. A dehydration reaction calls for 125 mmoles of cyclohexanol.  The density of cyclohexanol is 0.948.  Calculate the volume in mLs needed for the experiment.

[Arkcon]

OK, these problems involve density.  Do you know the definition of density?  It should be in your textbook.  It is a pretty simple equation. 

[NewbieScience66]

Yes, Density = mass/volume . I'm not understanding....

[Arkcon]

Yes, Density = mass/volume

Great.

. I'm not understanding....

Really?  What does the first part of the first question ask for and what info does it give.

[NewbieScience66]

So.... Do I set it up like this

0.785 g/ml = Mass / 825 uL           *825 uL = .825ml

(.825ml) 0.785g/ml = .647625g convert this to mg I would multiply by 1000 right?, so it would be 647.625mg

[NewbieScience66]

So then is the moles for second part of A like this....

.825ml (0.785g/ml)= .647625g

 .647625g/60.10g/mol = .01077 moles of 2-propanol

[NewbieScience66]

So, for the part B.

Do i set it up like this....

0.125 moles * 100.158g / 1 mol * 1 ml / 0.948g = 13.2 ml of cyclohexanol

[NewbieScience66]

So this what I have now.... am I on the right track.... I am stuck now on what 1:1 ratio is asking about...which on is the reactant and the product...

a. 2-propanol (60.10g/mol) has a density of 0.785 g/ml.  Calculate the mg in 825 uLs of 2-propanol.; Calculate the moles of 2-propanol in 825 uLs.   

825 uL = .825 ml
0.785 g/ml=mass/(.825 ml)

(.825 ml)0.785 g/ml= .647625 g

.647625 g ×1000=647.625 mg of 2"-propanol"

b. A dehydration reaction calls for 125 mmoles of cyclohexanol.  The density of cyclohexanol is 0.948.  Calculate the volume in mLs needed for the experiment.

0.125 moles ((100.158 g cyclohexanol)/(1 mol))  ((1 ml)/(0.948g cyclohexanol))=13.206 ml

c. The same reaction produces 0.495 grams of cyclohexene.  Calculate the moles of cyclohexene produced. 

0.495 g ((1 mol)/(82.143g cyclohexene))=0.00602 moles of cyclohexene


 Assume a 1:1 molar ratio of reactant to product in this reaction.  What is the theoretical yield of the product, cyclohexene, in moles?  What is the percent yield of cyclohexene?

[NewbieScience66]

So can anyone help?