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Tímea Szentgyörgyi - PowerPoint PPT Presentation

Rates of Reactions. SEK Budapest International School. Tímea Szentgyörgyi. 1021 Hungary,   Budapest, Hűvösvölgyi u. 131. Tel.:36-1-394-2968; Fax: 36-1-200-6615 www.sek.hu; www.sek.net.

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SEK Budapest International School

Tímea Szentgyörgyi

1021 Hungary,   Budapest, Hűvösvölgyi u. 131.Tel.:36-1-394-2968;

Fax: 36-1-200-6615

www.sek.hu; www.sek.net

• The rate of reaction, chemical reaction occurs and the factors that affect this speed. r, is defined to be the slope of the concentration-time plot for a species divided by the stoichiometric coefficient of that species.

• A + 2 B chemical reaction occurs and the factors that affect this speed. = 3 C

• r = -d[A]/dt = -1/2 d[B]/dt= 1/3 d[C]/dt

• The reactants have a negative slope, because they are being consumed in the reaction. Products have a positive slope, because they are being formed in the reaction.

What factors affect the rate of a reaction? chemical reaction occurs and the factors that affect this speed.

• The concentration of the reactants. The more concentrated the faster the rate. Remember for gasses, increasing the pressure simply increases the concentration so that's the same thing.

What factors affect the rate of a reaction? chemical reaction occurs and the factors that affect this speed.

• Temperature. Usually reactions speed up with increasing temperature.

• Physical state of reactants. Powders react faster than blocks - greater surface area and since the reaction occurs at the surface we get a faster rate.

• The presenceof a catalyst (or inhibitor). A catalyst speeds up a reaction, an inhibitor slows it down.

• Reaction with High Rates: chemical reaction occurs and the factors that affect this speed.

• 1. FeCl3 + KSCN → Fe( SCN)3 + 3 KCl

• 2. Faro’s snake

• Reaction with Middle Rates:

• FeCl3 + Na2S2O3 → [ Fe( S2O3)2 ]-

• Halloween reaction / Old Nassau Reaction

• The reaction in this chemical reaction occurs and the factors that affect this speed.

experiment takes place in

several steps [5].

• First, sodium

metabisulphite

reacts with water to form

sodium hydrogen sulphite:

Na2S2 O5 + H2O ==>

2NaHSO3

• Hydrogen sulphite ions

reduce iodate(V) ions to

iodide ions:

IO3- + 3 HSO3-==>

I- + 3 SO42+3H+

Reactions with low rates: iodide-iodate reaction

• 1. Pb( CH3COO)2 + 2KI = PbI2 +CH3COOK

• 2.NiCO3+2 dmg= [Ni( dmg)2]2+ + CO32-

• 3.CoSO4+2NH4SCN=Co(SCN)2 + (NH4)2 SO4

Thank you for your attention iodide-iodate reaction