[350chev]

Ok well I ran into a couple binds.

The first I believe I did properly but webassign says no.

Silver sulfadiazine burn-treating cream creates a barrier against bacterial invasion and releases antimicrobial agents directly into the wound. If 24.1 g of Ag2O is reacted with 48.2 of C10H10N4SO2, what mass of silver sulfadiazine (AgC10H9N4SO2) can be produced assuming 100% yield?

I came up with 68.6.

24.1g Ag2O/231.74=.103995 molAg2O X (359.1398 X 2)=74.697487

(48.2g 2C10H10N4SO2 X 2 X 359.1398) 504.5596 = 68.6

Since 68.6 is the smallest, it is the limiting reagent and would produce that amount. What did I do wrong?

Ok second question.

DDT, an insecticide harmful to fish, birds, and humans, is produced by the following reaction.
2 C6H5Cl   +   C2HOCl3   →   C14H9Cl5   +   H2O
chlorobenzene      chloral      DDT      


In a government lab, 1134 g of chlorobenzene is reacted with 481 g of chloral.




(c) What mass of the excess reactant is left over?
  g

(d) If the actual yield of DDT is 199.2 g, what is the percent yeild?
 %

For C I obtained 766.5336

To get that I:

found my moles in excess. 10.1 - 3.29 = 6.81

6.81 X 112.56 = 766.5336

To get D:

199.2/1134 X 100 = 17.566 percent

Where did I go wrong on that one?

Ok and last and not that difficult is a sig fig, thought I would throw it in here while I am here.

(c) What is the mass in grams of 4.49 mol of aspartame?
  Check the number of significant figures.

I got 1321.407

Its 3 sig figs but I cant remember how to work that one anyway simple one.

[Borek]

It is hard to tell what you did wrong in the second, not knowing how you have calculated numbers like 3.29...

In the first you are close, but it seems to me like 359.1398 is incorrect.

Note that technically speaking

24.1g Ag2O/231.74=.103995 molAg2O X (359.1398 X 2)=74.697487

this is abuse of equal sign.

[350chev]

It is hard to tell what you did wrong in the second, not knowing how you have calculated numbers like 3.29...

In the first you are close, but it seems to me like 359.1398 is incorrect.

Note that technically speaking

24.1g Ag2O/231.74=.103995 molAg2O X (359.1398 X 2)=74.697487

this is abuse of equal sign.

Well I reworked it to get a 68.9798 and it was wrong... I have one chance left on it and dont really know what calculation was off...

For the first one:

moles of C₆H₅Cl

1134/112.56=10.0746

moles of C₂HOCl₃

485/147.38884=3.2906

moles of DDT are 3.2906

moles in excess are 10.1-3.29

Sorry I was just trying to write out the equation. I will break up the = as best as I can in the future.

[Borek]

Well I reworked it to get a 68.9798 and it was wrong...

First approach was closer. I have already told you what was wrong - molar mass is not 359.

485/147.38884=3.2906

485 or 481?

Seems like you are prone to small mistakes in your math.

Sorry I was just trying to write out the equation. I will break up the = as best as I can in the future.

You may replace it with something like => so that it is obvious you don't mean 1=2, but 2 follows from things calculated in 1.

[350chev]

Well I reworked it to get a 68.9798 and it was wrong...

First approach was closer. I have already told you what was wrong - molar mass is not 359.

485/147.38884=3.2906

485 or 481?

Seems like you are prone to small mistakes in your math.

Sorry I was just trying to write out the equation. I will break up the = as best as I can in the future.

You may replace it with something like => so that it is obvious you don't mean 1=2, but 2 follows from things calculated in 1.

Sigh... math mistakes always get the best of me...

Anyway, I reworked my #1 and will repost it more clearly:

C₁₀H₁₀N₄SO₂ has a molar mass of 250.21

AgC₁₀H₉N₄SO₂ has a molar mass of 357.08

Ag₂O has a molar mass of 231.74

(24.1g Ag₂O X 1 mol Ag₂O X 2 mol AgC₁₀H₉N₄SO₂ X 357.08g AgC₁₀H₉N₄SO₂)/231.74g Ag₂O

74.2696g of AgC₁₀H₉N₄SO₂ is the product.

(48.2g C₁₀H₁₀N₄SO₂ X 2 mol C₁₀H₁₀N₄SO₂ X 2 mol AgC₁₀H₉N₄SO₂ X 357.08g AgC₁₀H₉N₄SO₂)/(500.42g X 2 mol)

68.78724 is the product.

Is 68.8 what I plug into webassign for proper sig figs? Or are my calculations wrong again?




Even after correcting my 485/481 error. Its supposed to be 481. I still end up with 6.81 X 112.56 = 766.5336?

Also, for the percent yield:

(199.2/1134)X100=17.566%. What is wrong with the percent yield calculation? Or do I multiply by 481 instead of 1134? If so why?

[350chev]

Alright for:

DDT, an insecticide harmful to fish, birds, and humans, is produced by the following reaction.
2 C6H5Cl   +   C2HOCl3   →   C14H9Cl5   +   H2O
chlorobenzene      chloral      DDT      
In a government lab, 1134 g of chlorobenzene is reacted with 481 g of chloral.

My mass of reactant left is 766.78. Why is it wrong?

C6H5Cl = 112.51
C2HOCl3 = 147.37
C14H9Cl5 = 354.39

My mass of DDT was correct but my left over is off?

I calculated it as 10.0791 mol of C6H5Cl - 3.26389 mol C2HOCl3 to 6.81521 mol of my limiting reagent C6H5Cl then multiplied by the molar mass 112.51 to get 766.7792

Here I got:

Silver sulfadiazine burn-treating cream creates a barrier against bacterial invasion and releases antimicrobial agents directly into the wound. If 24.1 g of Ag2O is reacted with 48.2 of C10H10N4SO2, what mass of silver sulfadiazine (AgC10H9N4SO2) can be produced assuming 100% yield?
Ag2O(s) + 2 C10H10N4SO2(s) → 2 AgC10H9N4SO2(s) + H2O(l)

68.787 and it tells me I am wrong.

Ag2O=123.87
C10H10N4SO2=250.21
AgC10H9N4SO2=357.08

Why am I wrong? Its due here at 11:50. Just want those two points...

Also sig fig on this:

(c) What is the mass in grams of 4.49 mol of aspartame?
  Check the number of significant figures. g

Its 3 sig figs but my answer is 1320.7784 how do I work 3 sig figs into that?

[350chev]

Any ideas guys?

[Borek]

I calculated it as 10.0791 mol of C6H5Cl - 3.26389 mol C2HOCl3

You have not accounted for the stoichiometry of the reaction.