Chemistry lesson

Practical work # 3 " Solving experimental problems on the topic "Hydrolysis.Ion exchangereagents "" - DISPERSED SYSTEMS. SOLUTIONS. PROCESSES OCCURRING in SOLUTIONS - LESSON DEVELOPMENTS in CHEMISTRY grade 11 - lesson developments-lesson developments - author's lessons - lesson plan-lesson summary - chemistry

Objectives of the lesson: to improve skills in performing a chemical experiment, observing the rules of OT and TB; to consolidate the ability to confirm theoretical knowledge with a chemical experiment.

Equipment: a set of reagents for each table (where there are acids, alkalis, salts, indicators); assignment of practical work in two variants.

Lesson progress

I. Organizational moment

Instructing students on the theoretical work, TB and FROM performing the work.

II. Performing work on options

Option I	Option II
1. To conduct an experiment between solutions of electrolytes. Mark the observed phenomena. Give a reasonable answer.
a) sodium carbonate and sulfuric acid. b) sodium hydroxide and zinc sulfate.	a) barium chloride and iron sulfate (II) b) potassium carbonate and hydrochloric acid
Equations of reactions are made in a molecular General and brief ionic form.
2. Examine the salt solutions with indicators.
a) zinc sulfate. b) potassium nitrate. C) sodium carbonate.	a) sodium sulfate b) iron(III) chloride) C) potassium sulfite
Explain the observed phenomena. Write the equation of hydrolysis in ionic and molecular forms.
3. What happens when electrolyte solutions are drained?
Aluminum chloride and sodium carbonate. When приливанииexcess al_{CL 3}or excess Na₂CO_{3 flows in}	A zinc pellet was placed in a solution of zinc chloride. If приливании HCl or excess ZnCl_{2 is present}

III. Homework assignment

To prepare for the control work № 3 on the topic "Chemical reactions. Disperse system. Processes occurring in solutions".

Answers to practical work tasks

Option I

Gas and water release is observed.

The ion exchange reaction goes to the end, because gas and iodine are formed — a weak electrolyte.

There is a precipitation of gelatinous, white, translucent sediment.

The reaction of ion exchange goes to the end, because a precipitate is formed, a very weak electrolyte.

2. The result of observations:

	ZnSO₄	KNO₃	Na₂CO₃
Base	Weak	Strong	Strong
Acid	Strong	Strong	Weak
pH	< 7	7	> 7>
Wednesday	Acidic Environment	Neutral	Alkaline
Universal indicator	Pink	Green	Blue
Phenolphthalein	—	-	Crimson
Litmus blue	Red	Purple	Blue
Methylorange	Pink-red	Orange	Yellow

the environment is acidic, the hydrolysis of the cation

the environment is alkaline, the hydrolysis of the anion

KNO₃-hydrolysis is not present, because the salt is formed by a strong base and a strong acid.

3. When merging solutions АlСl₃and Na₂CO₃there is a co-hydrolysis.

Gas is released if we take AlCl3 in excess₃; if we take Na2CO3 in excess₂CO₃, then gas and sediment are observed.

Option II

white sediment will fall out

The reaction of ion exchange goes to the end, because it forms a precipitate,

gas and water release is observed

The ion exchange reaction goes to the end, because gas and water are formed.

2. The result of observations:

	Na₂SOl	FeCI₃	K₂SO₃
Base	Strong	Weak	Strong
Acid	Strong	Strong	Weak
pH	7	< 7	> 7>
Wednesday	Neutral	Acid	Alkaline
Universal indicator	Green	Pink	Blue
Phenolphthalein	—	-	Crimson
Blue litmus	Purple	Red	Blue
Methylorange	Orange	Pink-red	Yellow

Na₂SO₄-no hydrolysis, the salt is formed by a strong base and a strong acid.

acidic environment, the hydrolysis of the cation.

the environment is alkaline, the hydrolysis of the anion.

When adding Zn, the medium is acidic, and hydrogen is released.

When HCl is added, zncl_{2 hydrolysis is weakened} and the rate of gas release decreases. When ZnCl_{2 is added}, hydrolysis is enhanced, and the rate of gas release increases.

Practical work # 3 " Solving experimental problems on the topic "Hydrolysis

II) b) potassium carbonate and hydrochloric acid

The reaction of ion exchange goes to the end, because a precipitate is formed, a very weak electrolyte

Gas is released if we take AlCl3 in excess 3 ; if we take

Phenolphthalein — -

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24.08.2020