Helping People with their maths homework :D

Discussion in 'Off-Topic' started by PhilsNZ, Sep 18, 2015.

  1. PhilsNZ
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    PhilsNZ Well-Known Member

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    Are you familiar with matrices or simultaneous equations? If so, this would make it much easier for you. If not, ill go through it in a different way
     
  2. Lycel
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    Lycel Senior Member

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    I at least know simultaneous equations, I can't remember if I know matrices or not.
     
  3. PhilsNZ
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    PhilsNZ Well-Known Member

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    Here you are, Lycel :)
    Allright, theres 2 ways to solve this. Theres a "traditional" way and an algebraic way. While the traditional way is easier for straightforward equations, the algebraic way will be a hell of a lot better for bigger equations. The Algebraic way works for any sized equation and is not a try/test way.
    Traditional way:
    H2SO4 + Pb(OH)4 --> Pb(SO4)2 + H2O
    We start with the Sulfate ions because we want to leave Hydrogen and Oxygen to the end.

    So we count the number of Sulfates on the left side and the number of Sulfates on the right hand side of the equation.
    Left: 1x (SO4) Right: 2x(SO4)
    So we immediately know that the sulfuric acid will have a coefficient of 2 or more. Lets chuck the 2 in there.
    2H2SO4 + Pb(OH)4 --> Pb(SO4)2 + H2O

    Now lets count the Lead atoms.
    Left: 1 Lead Right: 1 Lead
    These are balanced so lets not mess with them for now.

    Now lets balance the Hydrogens.
    Left: 8 Hydrogens Right: 2 Hydrogens
    So we see that the hydrogens are unbalanced. The left side has 4 times more hydrogen atoms. So we times the H2O by 4 to get a total of 8 Hydrogen atoms on both sides of the equation.
    2H2SO4 + Pb(OH)4 --> Pb(SO4)2 + 4H2O

    Now lets check the last atoms (Oxygen).
    Left: 12 Oxygens Right: 12 Oxygens
    Oh Look! They're all balanced :D
    So you end up with the final equation of:

    2H2SO4 + Pb(OH)4 --> Pb(SO4)2 + 4H2O

    Algebraic Way:
    H2SO4 + Pb(OH)4 --> Pb(SO4)2 + H2O

    The way's method is to form a simultaneous equation for each type of atom.
    Step 1: Bring everything from the equation over to one side (Left)
    H2SO4 + Pb(OH)4 --> Pb(SO4)2 + H2O
    turns to:
    H2SO4 + Pb(OH)4 - Pb(SO4)2 -H2O = 0 (Dont overlook the minus signs, they're important!)

    Step 2: Write every type of atom vertically below each other.
    Pb:
    S:
    O:
    H:
    Each of these atoms will form one equation (Hence the : )

    Now, give every compound involved a name. Its best to call them x1, x2, x3, x4... you can give them other names aswell like x, y, z, a...
    I'll use x, y, z, a to make it less confusing further on. These you write horizontally:


    [​IMG]


    Now comes the tricky part. You have to see how many of each atom in each compound.
    Eg. Pb(OH)4
    There is 1 Pb atom, 4 Oxygens and 4 Hydrogen atoms. And as Pb(OH)4 is = x2 you write the number of atoms in the x2 column as I will do now.

    [​IMG]

    Now we do the same things for the other compounds, however, the values of - Pb(SO4)2, -H2O will be Negative.
    H2SO4 + Pb(OH)4 - Pb(SO4)2 -H2O = 0

    So you should end up with this:

    [​IMG]

    So from this we can form 4 simultaneous equations :D
    You go across, and multiply the numbers by the x variable above them. Eg. The first equation will be:

    Pb: 0x + 1y - 1z +0a = 0 Which is Pb: 1y - 1z = 0
    S: 1x + 0y - 2z + 0a = 0 S: 1x - 2z = 0
    O: 4x + 4y -8z - 1a = 0 O: 4x + 4y - 8z - 1a = 0
    H: 2x + 4y - 0z - 2a = 0 H: 2z + 4y - 2a = 0

    So if we solve these 4 equations we get the values of x, y, z, a.
    x = the coefficient for the H2SO4
    y = the coefficient for Pb(OH)4
    z = the coefficient for Pb(SO4)2
    a = the coefficient for H2O

    These would be really simple to solve with matrices, but I'm really bad at drawing these on here so I'll use an online solver.
    Gyazo - 0ae53d9d0dd1fd4d6570f75f5da914d5.png
    Gyazo - 4c4d5b5b121c18f1ae5d3f138b16c35b.png
    Gyazo - d341d7daa97d39adbba5df5b95c823a0.png
    Gyazo - 3ffd4508f1951563d0d0fcda269252ba.png
    Gyazo - 9cf624ae4fc2e4662027383807104f25.png
    Gyazo - 8b044aae17413f29576da53c96fc5c1c.png


    The last page shows us that
    x1 = 1/2 = x
    x2 = 1/4 = y
    x3 = 1/4 = z
    x4 = Free = a This means that x4 or a is determined by the other 3 variables.
    So now lets put these coefficients into our equation:
    (1/2)H2SO4 + (1/4)Pb(OH)4 --> (1/4)Pb(SO4)2 + H2O
    So we times the whole equation by the biggest denominator to get whole numbers which is 4.
    4 * (1/2) * H2SO4 + 4 * (1/4) * Pb(OH)4 --> 4 * (1/4) * Pb(SO4)2 + 4 * H2O

    So our equation will end up as:
    2H2SO4 + Pb(OH)4 --> Pb(SO4)2 + 4H2O



    So that's it. Algebraic way is much more useful in higher level chemistry, but if you know that way, you'll be your classmates way ahead :)
    I hope this helped. If its still unclear, tell me and I'll try to simplify it even more :)
    Phew, this took me a whole hour to write xD
     
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    Last edited: Sep 23, 2015
  4. Lycel
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    Lycel Senior Member

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    Oh my gosh you have no idea how much this has helped :heart:3
    I'm clueless in Chemistry at the moment because they failed to teach this stuff to us in general science from year 8-10... but now I understand at least this! ^-^
    I didn't know you were such a nerd Phil :3 hehe.
    Thank you sososososooo much~
     
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  5. PhilsNZ
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    PhilsNZ Well-Known Member

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    Hahahaha no worries, it would be a shame for me to learn all that stuff but to never pass it on :)
     
  6. PhilsNZ
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    PhilsNZ Well-Known Member

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    Lycel look for any giveaways when using the traditional way, eg Polyatomic ions (SO4, NO3)
     
  7. PhilsNZ
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    PhilsNZ Well-Known Member

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    If anyone has more maths problems, feel free to hit me up ^^
     
  8. PhilsNZ
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    PhilsNZ Well-Known Member

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    GTechNerd do you know the algebraic way to balance equations?
     
  9. GTechNerd
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    GTechNerd Well-Known Member

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    Nah. I just do them in my head.
     
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  10. PhilsNZ
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    PhilsNZ Well-Known Member

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    Mooooore Maaaaaths!!!!!! FEEED ME MATHS!
     
  11. GTechNerd
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    GTechNerd Well-Known Member

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    Fine, here's one:

    Find the exact solution of the equation 9^2x = 27^(1-x). Have fun.
     
  12. PhilsNZ
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    PhilsNZ Well-Known Member

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    Thanks :D
    9^(2x) = 27^(1-x)
    => 3^(2(2x)) = 3^(3(1-x))
    => 4x = 3-3x
    => 7x = 3
    => x = 3/7

    Lol I resorted to logarithms first but then I realised the common factors ^^
     
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  13. RocketOG
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    RocketOG Guest

    Im in eighth grade and my science teacher is making me do high school physics if i have any questions ill come to you :)
     
  14. PhilsNZ
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    PhilsNZ Well-Known Member

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    Sweet as :D
     
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