single+displacement+reactions.+(teaching+wiki..)


 * SINGLE DISPLACEMENT REACTIONS**

//what happens:// in a single displacement reaction, an element and a compound react. the element switches places with the cation in the compound (the first element in the compound), and a new compound and element are formed.

//generic form of a single displacement reaction:// A + BC --> B + AC is a generic form of a single displacement reaction.

EXAMPLE EQUATION //equation in sentence form:// __aluminum and lead(II) nitrate react to form lead and aluminum nitrate__.

//change into formula equation:// aluminum is Al, lead is Pb and nitrate is NO3. lead nitrate would have the chemical formula of PbNO3 and aluminum nitrate would then have a chemical formula of AlNO3. with the addition symbols and a yields sign, the equation reads Al + PbNO3 --> Pb + AlNO3. but none of these formulas are correctly written or balanced yet.

//balancing the equation:// first, the formulas need to be written correctly so that the charges balance out to zero. in PbNO3, nitrate has a charge of -1, and lead has a charge of +2 because it is lead(II), normally it would have been + or -4. to balance the formula there need to be two nitrates. so PbNO3 becomes Pb(NO3)2. in AlNO3, nitrate still has a charge of -1 but aluminum has a charge of +3, so there need to be three nitrates; Al(NO3)3. now the equation is Al + Pb(NO3)2 --> Pb + Al(NO3)3. it still needs to be balanced. there is one Al on both sides. there is one Pb on both sides. but there are two NO3's on one side and three on the other. this is fixed by placing a coefficient of 3 in front of Pb(NO3)2 and a coefficient of 2 in front on Al(NO3)3. the equation is now Al + 3Pb(NO3)2 --> Pb + 2Al(NO3)3. but now there are two Al's on the product side, so the reactant side gets a coefficient of 2. there are also now three Pb's on the reactant side, so Pb on the product side gets a coefficient of 3. 2Al + 3Pb(NO3)2 --> 3Pb + 2Al(NO3)3, the equation is now balanced.



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