Поделиться
Урок 29.docx
Practical work # 2 on the topic " the Speed of chemical reactions. Chemical equilibrium" - CHEMICAL REACTIONS - LESSON PLANS for CHEMISTRY class 11 - lesson plans - lesson plans-author's lessons-plan-lesson summary - chemistry
Lesson objectives: to develop practical skills in performing a chemistry experiment (work with a spirit burner, heating substances in the flame, work with solutions of electrolytes), observing the rules of health and safety; to experimentally verify the influence of temperature, nature of reactants, catalyst, surface of contact: a) the rate of chemical reactions, b) the displacement of the chemical equilibrium.
Equipment: starch paste, solution I2; solution KI (0,4%), Fe-powder and chips; HCl; CuSO4(solution); CCL2 (solution); Zn (Gran.), luchinka, FeCl3; KNCS, CSL (Crist.), 4 test tubes each, alcohol lamp, matches, holder.
Lesson progress
I. Organizational moment
Briefing health and safety, the instruction of the execution sequence of work.
II. The implementation of practical work
Task 1. Influence of factors on the speed of chemical reactions:
a) the contact surface of reactants.
Conduct an experiment between a solution of hydrochloric acid and iron metal taken in the form of chips and powder.
To compare the rate of reaction. Give a reasonable answer.
b) temperature. Conduct an experiment between solutions of KI and H2O2without heating and when heated. Mark the time when the solution color changes. Make informed conclusions.
H2O2— hydrogen peroxide; KI-0.4% solution of KI; (C6H10O5)n-starch paste (it can be pre-mixed with KI solution).
C) the nature of the reactants. Experimentally compare the reaction rates of interaction of mg and Fe metals with hydrochloric acid. Give a reasonable answer;
d) the catalyst. Experimentally compare the reaction rates of interaction of a zinc granule with a solution of CuSO4and Sucl2. Give a reasonable answer.
Task 2. Influence of certain factors on the shift of chemical equilibrium.
a) factor-change in the concentration of reactants and end products. Experimentally confirmed on the experience of interaction of solutions of FeCl3and KNCS. In four test tubes, pour 1 ml of water, add 1-2 drops of FeCl3and 1-2 drops of KNCS. Mark the observed phenomena. Then add 1-2 drops of FeCl 3 to tube # 13; 1-2 drops of CNCS to tube # 2; and TV to tube # 3 тв. CSl, tube # 4 remains for comparison. To note the necessary conditions. Give a reasonable answer;
b) factor-temperature.
Experimentally confirm the influence of temperature on the equilibrium shift of the reaction of interaction of starch paste and solution I2. Give a reasonable answer.
III. Registration of practical work in the table:
|
The task |
of Monitoring the reaction equations |
Conclusions |
IV. Homework assignment: repeat sections 11-14; prepare for the test.
Answers to questions in practical work assignments # 2
|
Setting |
the Observation, reaction equations |
The Findings Of |
|
The Task № 1. Influence of certain factors on the rate of chemical reactions |
||
|
a) the contact surface of reacting substances. Experiment: — HCl and Fe(por.); - HCl and Fe(p.) |
|
V1> V>2, since according to the formula
S-the unit of area Fe(por.) is less than the unit of areaFe(p.) |
|
b) temperature: a mixture of KI and H2About2(starch paste without t°) |
(starch paste, there is a slow color change-transition to blue) |
I2causes the starch to turn blue slowly |
|
KI and H2O2(starch paste at t°) |
instant bluing of the solution
|
OVR at t° is very fast, becauseEact.decreases |
|
(C) the nature of the reactants: Mg(por.) and HCl Fe(por.) andNSL |
|
The radius Of the mg atom is greater than the radius of the iron atom, the reducing capacity of Mg is greater than the reducing capacity of Fe, Mg atoms require E0less |
|
than g) catalyst: compare two reactions Zn and CuSO4 Zn and CuCl2(3-4 caps.) CuSO4 |
is observed to appear stranded, the reaction proceeds at a low speed |
Reducing capacity Zn is greater than reducing capacity Withu, Zn displaces si from the salt solution |
|
, the appearance of copper is observed, but the reaction is very fast |
In the salt solution
, as a result of dissociation, anions withl-are present, which act as a catalyst, the reaction rate is high V2> V>1 |
|
Task 2. the Influence of certain factors on the mixing of chemical equilibrium
|
a) factor-change in the concentration of reactants and end products |
Test tube |
color of the complex salt K3[Fe(NCS)6] light red |
|||
|
, No. 1 H2O FeCl 1-2 to3 1-2 to KNCS |
n 2 H2O FeCl 1-2 to3 1-2 to KNCS |
n 3 H2O FeCl 1-2 to3 1-2 to KNCS |
No. 4 H2O FeCl 1-2 to3 1-2 to KNCS |
||
|
color light red, |
|||||
|
then add 1-2 to the FeCl3 |
In a test tube # 1 color |
||||
|
# 1 |
# 2 |
# 3 |
# 4 |
||
|
original product |
Since the concentration ofFeCl 3is increased, the equilibrium will mix towards the formation of K3[Fe(NCS)6] |
||||
|
add 1-2 tothe KNCS enhanced color |
Increased color in test tube # 2 for the same reason-the balance is shifted towards the formation of the final product there is a direct reaction |
||||
|
add KCl(kr.), the color of the solution became yellow |
for comparison |
The concentration of the final product is increased, the equilibrium is shifted towards the formation of initial products, i.e. there is a reverse reaction |
|||
|
b) temperature starch paste and solution I2 |
At normal temperature
, dark blue staining |
A compound of amyrase with molecules I2is formed, the color is dark blue, the reaction is exothermic |
|||
|
starch paste and solution I2when heated |
Heat the dark blue solution — the color disappears, because
there is a dark blue color of the solution When cooling |
When heated, the balance shifts towards the endothermic reaction, there is a reverse reaction |
|||
Conclusions: Experiments have convincingly proved the influence of certain factors on the rate of chemical reactions and on the shift of chemical equilibrium. Additionally: influence of both temperature and catalyst on the reaction rate. In the case of the influence of the catalyst and t° on the reaction rate it is possible to conduct a decomposition reaction H2O2:
a) when heated without a catalyst
b) when heated and in the presence of an MPO2 catalyst
The release of oxygen can be proved by a glowing splinter.
Материалы на данной страницы взяты из открытых источников либо размещены пользователем в соответствии с договором-офертой сайта. Вы можете сообщить о нарушении.
