When certain dicarbonyl compounds are treated with base intramolecular Aldol reactions can occur. Similarly diesters can undergo intramolecular Claisen Condensations (this reactions is known as the Dieckmann cyclisation).
In redox reactions, electrons are transferred and elements acquire different oxidation numbers. Balancing oxidation reduction reactions that cannot be classified as any other type of reaction requires a slightly different technique. We will balance them using an approach known as half reactions. In this method, the overall equation is split into two parts. One part shows what happens to the element whose charge is increasing, the oxidation step. The other half reaction shows what happens to the element that is losing charge, the reduction step.
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Notice that the oxygen is not a single atom. Remember that there are seven elements that are diatomics, they always hold hands with a twin. These molecules (Br, I, N, Cl, H, O, and F) will always come in pairs when they are elemental. That does not mean they stay in pairs when they break apart to form compounds with other molecules in a reaction.
The complete chemical equation tells us more information as well. It tells us the state of the reactants and products by using (g) for gas, (s) for solid, (l) for liquid, and (aq) for aqueous (dissolved in water) substances. The magnesium equation would more completely be written by including these subscripts that denote the phase:
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Review and extend CCBFR from 1C1Y, in particular:
Aldol and Claisen condensations
Alkylation of -keto esters (RCHOCH2CO2R’)
Chemical Equations & Reactions (1) will be available on
Some decomposition reactions require heat or some form of energy to occur. The fact that heat is involved may be indicated with an arrow like this .
In aromatic chemistry CCBFR revolve around:
The basic form of the equation is element + compound element + compound or B + AC C + AB. Notice that the anion or the cation may be replaced. Also notice that the charge or oxidation number of some of the elements in the reaction is changing. Zinc is initially uncharged but has a +2 charge in zinc chloride. When charges change in a reaction, the reaction is also classified as a oxidation reduction reaction. More on this later.
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Reactions are usually straightforward (SEAr) and you will have met most of them before. Synthesis is simplified because the nature of the starting materials is usually clear. Thus, most reactions correspond to the following disconnection:
PS3.D: Energy in Chemical Processes and Everyday Life
Why does the zinc replace the hydrogen? To answer this, we need to consider the activity of different metals. Metals all have varying degrees of activity. The more active the metal the more able it is to replace another metal. It is as if the more active metal is the stronger, better looking, and nicer metal so the pretty little cation switches her date. How do we know which is stronger since we aren't seeing the
metal through the cation's eyes? We have to consult an . This is simply a list of metals along with hydrogen ordered with the strongest metal on top and the weakest on bottom. Any metal that is above another metal will replace it in a reaction. If the metal is below the metal in the reacting compound, it will not react. In other words, H2 would not replace the zinc in zinc chloride.
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