ElectricPavlov

Ooops....didn'y answer all of the questions...

#2    2 moles of  AuO3  produce 4 moles of Au

      .4797 moles Au2O3  x 2 = .9594 moles Au produced

#3  85 grams of Au = 85/196.96 mole          1/2 as many moles Au2O3 is needed

      85/196.96   x  1/2 = .4315 moles

we already found Au2O3 moles weigh 441.937 gm

     .4315 mole x 441.937 gm/mole = 190.72 gms of Au2O3 are needed

x= y^2-6y+8      -b/2a     is vertex point y    =    -   -6/2 = 3  Sub in to find the x value

x = 3^2- 6(3) +8= -1

(-1,3)

Circumference of larger circle = pi d =   18 pi

smaller circle = 4 pi

 After 20 revolutions the smaller circle travels 20 * 4 pi = 80 pi

    18 pi is one complete travel around the larger circle

     80 pi -   18 pi *4    = 8pi  = the tangent point

8pi /18pi  x 360 = 160 degrees.  

I was taking a nap !   ZZZZZzzzzzZZZZZ    Haha .....now I'm going for a run !  

From the equation we can see that    3 moles of O2 are produced in the reaction

   at STP    , one mole of gas occupies   22.4 liters  (remember that?....we'll need it shortly)

       3 x 22.4 = 67.2 liters for the COMPLETE reaction in the equation......we are only going to get some fraction of this reaction because we are only using  212 gm of gold oxide

Au2O3   has a molar weight  of   2( gold)  + 3(oxygen)  =  2(196.97 ) + 3 (15.999) = 441.937 gm   (from periodic table)

     we only have   212 gm of this stuff   which represents   212/441.937 = .4797 moles of Au2O3

ONE MORE THING    Look at the equation given:    for every   2 moles of Au2O3 used , you GET 3 moles of 02

   so  you get   3/2 as much O2 in moles as moles of Au2O3 used .......THIS NEEDS TO BE CLEAR.....OK?

.4797 moles AuO3  x 3/2 = .71955 moles of O2 produced

Now remember earlier that an ideal gas at STP = 22.4 liters ???????

22.4 liters/mole   X   .71955 moles = 16.118 liters of O2 at STP

arcsin (1/2)  =   30     150

arcsin (-1/2) =   330        210 degrees     

Sorry! (for the edits)

Since we are looking for Sue's age now, let x = Sue's age now

x+SID =30

    and

SID-8 = x-2    re-arrange

SID = x+6     sub into the first equation

x  +   x+6 = 30

x = 12

Deleted ....

csc = 1/sin

csc^2 = 1/sin^2

1/ sin^2 = 4

sin^2 = 1/4

sin = +- 1/2        Got it from here?

The angle just to the right of 75 is the same as x

    75 and that angle add to 180 ( a straight line)

      x = 105 degrees