Anonymous asked in Science & MathematicsChemistry · 8 years ago

i dont understand how to balance chemical equations?


4 Answers

  • 8 years ago
    Favorite Answer

    I have some explanations, examples and videos here:

    Look for other materials and videos. Try Kahn Academy and kentchemistry.

    Here's a small example:

    Li + H3PO4 ---> H2 + Li3PO4

    Balance the Li:

    2Li + H3PO4 ---> H2 + Li3PO4

    Now, look at the hydrogens. See how the H comes only in groups of 3 on the left and only in groups of 2 on the right? Do this:

    3Li + 2H3PO4 ---> 3H2 + Li3PO4

    See how 2 x 3 = 6 and 3 x 2 = 6?

    Balance the phosphate as a group:

    3Li + 2H3PO4 ---> 3H2 + 2Li3PO4

    Oops, that screwed up the lithium, so we fix it:

    6Li + 2H3PO4 ---> 3H2 + 2Li3PO4

    And it's done.

    It looks easy, but it does take some practice. I have I've helped and best wishes in all your studies, not just chemistry.

  • 8 years ago

    The principle is quite simple actually. The way I think about it is the following: when you have a chemical equation the number of elements HAS to be the same. So the part before and after the arrow have to have the same number of elements. For instance..

    __NaCl + __BeF2 --> __NaF + __BeCl2

    Before the arrow there are:

    1 Na 1 Cl 1Be 2F

    Ater the arrow there are:

    1Na 2 Cl 1Be 1F

    As you see the chemical equation in unbalanced. Comparing the "before the arrow" with the "after the arrow" there are two Cl and only one F. Hence we need to multiply some molecules to make the end result the same as the starting result.

    The answer is therefore:

    2 NaCl + 1 BeF2 --> 2 NaF + 1 BeCl2

    Now we have:

    Before the arrow there are:

    2 Na 2 Cl 1Be 2F

    Ater the arrow there are:

    2Na 2 Cl 1Be 2F

  • Anonymous
    8 years ago

    say you had H2O yields H2 + O2

    on the right side you have 2 oxygen but on the left side you only have 1, so you have to put a 2 in front of the H2O on the left side to make the O's balanced. But since you put a 2 in front of the H2O and there was already 2 H there are now 4 H on the left side and only 2 on the right so you also have to put a 2 in front of the H2 on the right side.

    so your original equation was H2O yields H2 + O2

    your balanced equation would be 2H2O yields 2H2 + O2

    there are now 4H on both sides and 2O on both sides

  • Chris
    Lv 7
    8 years ago

    There are two steps.

    1. Write the correct formulas, using subscripts

    2. Obey the law of conservation of mass, using coefficients

Still have questions? Get your answers by asking now.