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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

ZZZZZZ

It’s about time EP! Jenny has been waiting for hours and hours!

It's ok about the edits! I figured out what you were trying to say. And then I just use the 4 quadrants im assuming (theta+180, -180 and -360)

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

So with sin^2x = 1/4 how do i find the values of x between 0 and 360 degrees

Deleted ....

csc = 1/sin

csc^2 = 1/sin^2

1/ sin^2 = 4

sin^2 = 1/4

sin = +- 1/2        Got it from here?

Thanks guys for the help!

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

Tan =  -4/3

Arctan(-4/3) = -53.130102354156+180 = 126.869897645844

-53 is the reference angle between  - pi/2   and + pi/2   so....

Think about the coordinate plane   the point    -3 , 4  is in Quadrant 2   and the answer is   126.87 degrees

Hi Jenny, I cannot help either but I would like to suggest that you use a title like:

Chemistry - help needed please.

It is better when people use less generic titles.

Thanks!

See my  corrected answer....I hope it is clear...

The total number of odds is  15

The average is just the same as the median of the data set  = 35

thank you, but could you explain what you did? 

Here's my attempt....whether it's correct....I don't know....

Just a little trial and error

{ 1,4, 7,  10, 13,..... }

2004 is divisible by 3

So....2005  would be the next integer that is one more than a multiple by 3....which is also a characteristic of the integers in the first set 

So....we can find the number of elements by  

2005 = 1 + 3(n - 1)

2005 = 1 + 3n - 3

2005 = 3n - 2

2007 = 3n

n = 669 elements =  the max elements that can be chosen without having the sum of any two being divisible by 3

\(m^6+5m^3-10=0\\ let \;\;x=m^3\\ x^2+5x-10=0\)

Now it is in quadratic form.

NOTE:  Your question was automatically hidden because you used the word "stupid".

             I had to manually unhide it. That is why it was not answered for so long.

Let Sid's age be A

Then Sue's age is  30 - A

And 8 years ago....Sid's age was A - 8

And 2 years ago, Sue's age was 30 - A - 2   =   28 - A

And we know that

A - 8  = 28 - A      add A, 8 to both sides

2A = 36     divide both sides by 2

A = 18

So... Sue is   30 - 18   =  12 

Thank you for attempting. I will wait for him this is very important. I wish i understood it

I can't answer these, jenny....but....I believe that EP knows some Chemistry.....he will probably be on in a while.....

0.02%

Drop the %  sign.......move the decimal two places to the left  ⇒

.0002

1 1/3    =   4/3

So we have

8/7 - (-4/3) =

8/7  +  4/3  =

24/21 + 28/21 =

52 / 21

Auugh....   do you see where you got off-course!   Your boat is now stuck on the reef doing tremendous damage !  

it is    3  *  x    -6            not          3 + x   -6

Oh i did it like this 

3x-6+2x+88+108=360

solved and got 34

then i substituted x for 34  in the A equation 

3+34-6 and got 31..