Практикум (русский язык). 6 Лабораторная работа 1

ЛАБОРАТОРНЫЙ ПРАКТИКУМ (АНГЛИЙСКИЙ ЯЗЫК)

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Cations Classification

ЛАБОРАТОРНЫЙ ПРАКТИКУМ (АНГЛИЙСКИЙ ЯЗЫК).

1-LW Technique of laboratory works. Safety. Cations Classification .

Laboratory safety

All students must read and understand the information in this document with regard to laboratory safety and emergency procedures prior to the first laboratory session. Your personal laboratory safety depends mostly on YOU. Effort has been made to address situations that may pose a hazard in the lab but the information and instructions provided cannot be considered all-inclusive.

Students must adhere to written and verbal safety instructions throughout the academic term. Since additional instructions may be given at the beginning of laboratory sessions, it is important that all students arrive at each session on time.

With good judgement, the chance of an accident in this course is very small. Nevertheless, research and teaching workplaces (labs, shops, etc.) are full of potential hazards that can cause serious injury and or damage to the equipment. Working alone and unsupervised in laboratories is forbidden if you are working with hazardous substances or equipment. With prior approval, at least two people should be present so that one can shut down equipment and call for help in the event of an emergency.

Safety training and/or information should be provided by a faculty member, teaching assistant, lab safety contact, or staff member at the beginning of a new assignment or when a new hazard is introduced into the workplace.

Personal and General laboratory safety

Never eat, drink, or smoke while working in the laboratory.
Read labels carefully.
Do not use any equipment unless you are trained and approved as a user by your supervisor.
Wear safety glasses or face shields when working with hazardous materials and/or equipment.
Wear gloves when using any hazardous or toxic agent.
Clothing: When handling dangerous substances, wear gloves, laboratory coats, and safety shield or glasses. Shorts and sandals should not be worn in the lab at any time. Shoes are required when working in the machine shops.
If you have long hair or loose clothes, make sure it is tied back or confined.
Keep the work area clear of all materials except those needed for your work. Coats should be hung in the hall or placed in a locker. Extra books, purses, etc. should be kept away from equipment, that requires air flow or ventilation to prevent overheating.
Disposal - Students are responsible for the proper disposal of used material if any in appropriate containers.
Equipment Failure - If a piece of equipment fails while being used, report it immediately to your lab assistant or tutor. Never try to fix the problem yourself because you could harm yourself and others.
If leaving a lab unattended, turn off all ignition sources and lock the doors.
Never pipette anything by mouth.
Clean up your work area before leaving.
Wash hands before leaving the lab and before eating.

Chemical safety

Treat every chemical as if it were hazardous.
Make sure all chemicals are clearly and currently labeled with the substance name, concentration, date, and name of the individual responsible.
Never return chemicals to reagent bottles. (Try for the correct amount and share any excess.)
Comply with fire regulations concerning storage quantities, types of approved containers and cabinets, proper labeling, etc. If uncertain about regulations, contact the building coordinator.
Use volatile and flammable compounds only in a fume hood. Procedures that produce aerosols should be performed in a hood to prevent inhalation of hazardous material.
Never allow a solvent to come in contact with your skin. Always use gloves.
Never "smell" a solvent!! Read the label on the solvent bottle to identify its contents.
Dispose of waste and broken glassware in proper containers.
Clean up spills immediately.
Do not store food in laboratories.

Cations Classification

For selection of cations on analytical groups used group reagents. Accordance to applied group reagents all cations are divided on various systems. Cations divide to analytical groups in according with solubility of salts, formed by its.

Use of general and group reagents gave rise to creation the series of analytical cations classifications. Most widely used from them are sulphide, acid-basic and ammonia-phosphate. Analytical classifications of cations are based on chemical properties of their compounds and are associated with disposition of elements in periodic table, their structure and physico-chemical properties.

In all classifications there is a cations group, which does not have group peagent (cations of lithium, potassium, sodium, and ion of ammonium, which has the ion radius similar to the potassium ion). These are cations of thes elements with electronic structure of inert gas, low electronegativity, with small radius, and small polarisation properties. Majorities of their salts are well water-soluble by reason of high tie polarity. In periodic system they dispose in ІА-sub-group. In sulphide classification to this group is concluded a magnesium cation, which has similar lithium cation properties.

In all of classifications identical is the group of cations, which sediment by sulphate acid, ammonium carbonate, and sodium hydrogenphosphate in ammonia presence. There are the cations of thes elements: calcium, barium, and strontium, which are found in ІІА-sub-group of periodic system. Precipitates of their carbonates, sulphates and phosphates formed with complicated anions of oxygen-containing acids, which lightly polarize. In phosphate classification here are included cations of the s-elements – magnesium, and d-elements – iron (ІІ and ІІІ), chrome (ІІІ), manganese (ІІ), which form precipitates with three-charged phosphate-ion, and cations of the р-elements – aluminum (ІІІ) and bismuth (ІІІ), which have similarly low electronegativity.)

All classifications also include a group of cations, which form precipitates with НСІ: silver (I), mercury (I), and lead (ІІ). First two are the d-elements and lead is the р-element.

From cations of other groups can be picked out the ampholytic cations of the р- and d-elements, which have amphoterric properties and disposed bias of periodic table – zinc (ІІ), aluminium (ІІІ), teen (ІІ, IV), arsenic (ІІІ, V), chrome (ІІІ). Theyare found identical groups of analytic classifications. The ampholytes inherent small electronrgativity, high polarising properties and their compounds is capable to dependence on conditions to display oneself both base and acids.

Sameness disposition attitude in analytic groups has cations giving the complexes with ammonia. There are cations of the d-elements – nickel (ІІ), cobalt (ІІ), cadmium (ІІ), mercury (ІІ), copper (ІІ). High ability to complex compounds formation intrinsic explains by acceptor properties of unfilled in d-orbitals.
Types of Analytical Classifications of Cations

Group	Group reagent	Cations
ACID-BASIC
I	There are not	K⁺, Na⁺, Li⁺, NH₄⁺
ІІ	HCl	Ag⁺, Pb⁺², Hg₂⁺² Chlorides, insoluble in water and acids
ІІІ	H₂SO₄	Ca⁺², Sr⁺², Ba⁺² Sulphates, insoluble in water, acids and bases
IV	NaOH	Al⁺³, Zn⁺², Cr⁺³, Sn⁺²,Sn⁺⁴, As⁺³, As⁺⁵ Hydroxides with amphoteric properties
V	NaOH	Mn⁺², Mg⁺², Fe⁺², Fe⁺³, Sb⁺³, Sb⁺⁵, Bi⁺³ Hydroxides insoluble in ammonia and bases
VI	NH₃	Cu⁺², Co⁺², Cd⁺², Ni⁺², Hg⁺² Hydroxides soluble in ammonia with ammonia complexes formation
SULPHIDE
I	There are not	K⁺, Na⁺, Li⁺,NH₄⁺
ІІ	(NH₄)₂CO₃ + NH₃ + NH₄Cl	Ca⁺², Sr⁺², Ba⁺², Mg⁺² Carbonates insoluble in water
ІІІ	(NH₄)₂S + NH₃ + NH₄Cl	Mn⁺², Fe⁺², Fe⁺³, Co⁺², Ni⁺², Zn⁺², Cr⁺³, Al⁺³ Sulphides insoluble in water, ammonia but soluble in НСІ
IV	H₂S + HCl	Cu⁺², Cd⁺², Hg⁺², Sn⁺², Sn⁺⁴, As⁺³, As⁺⁵, Sb⁺³, Sb⁺⁵, Bi⁺³ Sulphides insoluble in НСІ
V	HCl	Ag⁺, Pb⁺², Hg₂⁺² Chlorides, insoluble in water and acids
AMMONIA-PHOSPHATE
I	There are not	K⁺, Na⁺, NH₄⁺
ІІ	(NH₄)₂НРO₄ + NH₃	Ca⁺², Sr⁺², Ba⁺², Mg⁺²Li⁺, Mn⁺², Fe⁺², Fe⁺³, Cr⁺³, Al⁺³Bi⁺³ Phosphates insoluble in water and ammonia
ІІІ	Nа₂НРO₄	Cu⁺², Co⁺², Cd⁺², Ni⁺², Hg⁺², Zn⁺² Phosphates soluble in ammonia with ammonia complexes formation
V	НNO₃	Sn⁺², Sn⁺⁴, As⁺³, As⁺⁵, Sb⁺³, Sb⁺⁵ Oxidize to compounds with the highest oxidation numbers
VI	HCl	Ag⁺, Pb⁺², Hg₂⁺² Chlorides insoluble in water and acids

2-LW Qualitative reactions for cations of analytical group 1.

Task:

In notebook to prepare the report on laboratory work that includes the General characteristics of this group of ions, reaction with group reagent and private reactions of ions. To perform laboratory work (experiments, see below), to complete the report observations.

Еxperiments:

Characteristic reactions of Potassium cations K⁺

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