پاورپوینت واکنشهای شیمیایی در محلولهای آبی

بخشی از پاورپوینت

اسلاید 2 :

واکنشهای شيميايي در محلولهای آبی

اسلاید 3 :

Chemical Reactions
The following table summarizes the common Driving forces that tend to make reactions go in the direction of the arrow:

Reactants  Products

When two or more chemicals are brought together, if any of the above can occur, a chemical reaction is likely to take place!
Formation of a solid
Formation of water
Formation of gas
Transfer of electrons

اسلاید 4 :

CHEMISTRY
- science of properties and transformations of matter
CHEMICAL REACTIONS - central to CHEMSITRY
CLASSIFICATION of REACTIONS

Precipitation

Oxidation-reduction

Acid-base

Gas forming

اسلاید 5 :

Precipitation ReactionsSolubility Rules
There are simple guidelines that allow one to predict whether or not a reaction will produce an insoluble compound: these are called the Solubility Rules

اسلاید 7 :

Ionic Equations:Net Ionic
The ions that appear on both sides of the equation in identical forms. These ions are not involved directly in the reaction and are called spectator ions.

In the net ionic equation, the spectator ions are omitted leaving only the ions directly involved in the reaction.
Pb2+(aq) + 2NO3-(aq) + 2K+(aq) + 2I-(aq)  PbI2 (s) + 2K+(aq) + 2NO3-(aq)
spectator ions
Pb2+(aq) + 2I-(aq)  PbI2 (s)

اسلاید 8 :

Ionic Equations:Summary
Summary of the 3 different chemical equations:
Molecular equation
Complete ionic equation
Net ionic equation
Pb(NO3)2(aq) + 2KI(aq) PbI2 (s) +2KNO3(aq)
Pb2+(aq) + 2NO3-(aq) + 2K+(aq) + 2I-(aq) PbI2 (s) + 2K+(aq) + 2NO3-(aq)
Pb2+(aq) + 2I-(aq) PbI2 (s)

اسلاید 9 :

Acid-Base Reactions: Neutralization
Consider the reaction between Mg(OH)2 [milk of magnesia] and HCl (stomach acid)
The net reaction is:
The acid has been neutralized

اسلاید 10 :

یونهای دارای عدد اکسایش و کاهش متفاوت

اسلاید 11 :

Half-Reaction Method Of Balancing Redox Equations
Assign oxidation numbers to each atom and identify the species undergoing oxidation and reduction. Write two skeleton half-reactions.
oxidation # increase => oxidation; oxidation # decrease => reduction
(1) Balance the numbers of atoms in each half-reaction.
(a) Balance all atoms except O and H.
(b) Balance O atoms by adding H2O molecules.
(c) Balance H atoms by adding H+ ions.
(2) Balance electric charge by adding electrons to more positive side.
(3) Combine two half-reactions to obtain balanced equation.
(a) Multiply each half-reaction by factors that make the number of
electrons in two half-reactions equal.
(b) Combine the adjusted half-equations into an overall equation.
Simplify the balanced equation if necessary.
Verify that the equation is balanced.

اسلاید 12 :

Balance the following redox equation in acidic solution:
Fe2+ (aq) + Cr2O72- (aq)  Fe3+ (aq) + Cr3+ (aq)
Fe2+ (aq)  Fe3+ (aq)+e
Cr2O72- (aq) +e  Cr3+ (aq)

اسلاید 13 :

سينتيک شيميايی

اسلاید 14 :

تعریف سینتیک شیمیایی
قانون سرعت و مرتبه واکنش
روشهای تشخیص مرتبه واکنش
عوامل موثر بر سرعت واکنش
اثر غلظت
اثر دما
اثر کاتالیزگر
نظریه هاو مدلهای حاکم بر سینتیک شیمیایی
نظریه برخورد
نظریه حالت گذار

اسلاید 15 :

تعریف سینتیک شیمیایی

ترمودینامیک شیمیایی علمی است که پیرامون خود بخود بودن یا خود بخود نبودن یک تغییر فیزیکی یا شیمیایی از نظر انرژی مطالعه می نماید
سینتیک شیمیایی مطالعه سرعت یا تندی واکنش های شیمیایی است. عوامل کمی در تعیین سرعت یک واکنش دخالت دارند. مطالعه این عوامل به ما کمک می کند تا سر نخهایی پیرامون نحوه تبدیل مواد واکنش دهنده به فراورده ها در واکنش شیمیایی بدست آوریم. مسیر تبدیل مواد اولیه به محصول مکانیسم واکنش نام دارد.

اسلاید 17 :

تعریف سرعت واکنش

Reaction rate: changes in a concentration of a product or a reactant per unit time.
[ ] concentration Reaction rate = ——  t

change
Define reaction rate and explain Average reaction rate= Instantaneous reaction rate (2 tangents shown)Initial reaction rate

اسلاید 18 :

سرعت نسبی واکنش
For a chemical reaction, there are many ways to express the reaction rate. The relationships among expressions depend on the equation.
Note the expression and reasons for their relations for the reaction
2 NO + O2 (g) = 2 NO2 (g)
[O2] 1 [NO] 1[NO2] Reaction rate = – ——— = – — ———— = — ———  t a t b  t
Make sure you can write expressions for any reaction and figure out the relationships. For example, give the reaction rate expressions for
2 N2O5 = 4 NO2 + O2
How can the rate expression be unique and universal?

اسلاید 19 :

Calculating reaction rate
The concentrations of N2O5 are 1.24e-2 and 0.93e-2 M at 600 and 1200 s after the reactants are mixed at the appropriate temperature. Evaluate the reaction rates for
2 N2O5 = 4 NO2 + O2
Solution: (0.93 – 1.24)e-2 – 0.31e-2 MDecomposition rate of N2O5 = – ———————— = – —————— 1200 – 600600 s
= 5.2e-6 M s-1.
Note however,rate of formation of NO2 = 1.02e-5 M s-1. rate of formation of O2 = 2.6e-6 M s-1.
The reaction rates are expressed in 3 forms
Be able to do this type problems

اسلاید 20 :

سرعت کلی واکنش یا قانون سرعت
Dependence of reaction rate on the concentrations of reactants is called the rate law, which is unique for each reaction.
For a general reaction, a A + b B + c C products
the rate law has the general form
order wrt A, B, and C, determined experimentally  reaction rate = k [A]X [B]Y [C]Z  the rate constant
For example, the rate law is
rate = k [Br-] [BrO3-] [H+] for
5 Br- + BrO3- + 6 H+  3Br2 + 3 H2O
The reaction is 1st order wrt all three reactants, total order 3.
Use differentials to express rates