# data[].attributes.body
electrolysis of brine

# data[].attributes.attachment_link.readable_text
is a solution of sodium chloride (NaCl) and water (H ₂O). The process of electrolysis involves using an electric current to bring about a chemical change and make new chemicals. The electrolysis of brine is a large-scale process used to manufacture chlorine from salt. Two other useful chemicals are obtained during the process, sodium hydroxide (NaOH) and hydrogen (H ₂).

It is important that the chlorine and sodium hydroxide produced in the process are separated they react when they come into contact with each other.
Uses in industry
Product of electrolysis of brine

Chlorine - disinfectant and purifier, manufacture of hydrochloric acid and making plastics

Sodium Hydroxide - processing food products, removing pollutants from water and manufacture of paper

Hydrogen - manufacture of hydrochloric acid and potential as a pollution-free fuel

Environmental impacts of the electrolysis of brine on a large scale must be considered. The process uses a lot of electricity that is mainly produced by the burning of fossil fuels. During the actual process of electrolysis, metal must be in contact with the solution of brine. A metal commonly used is mercury which is toxic. Some mercury escapes into the solution and into the environment.

This video explain more about Electrolysis

# data[].attributes.attachment_link.title
Electrolysis of Brine - Chemistry GCSE Revision

# data[].attributes.attachment_link.description
is a solution of sodium chloride (NaCl) and water (H 2O). The process of electrolysis involves using an electric current to bring about a chemical change and make new chemicals. The electrolysis of brine is a large-scale process used to manufacture chlorine from salt.

# data[].attributes.body
Uses of electrolysis

# data[].attributes.attachment_link.readable_text
Aluminium-air batteries (Al-air batteries) produce electricity from the reaction of oxygen in the air with aluminium. They have one of the highest energy densities of all batteries, but they are not widely used because of problems with high anode cost and byproduct removal when using traditional electrolytes. This has restricted their use to mainly military applications. However, an electric vehicle with aluminium batteries has the potential for up to eight times the range of a lithium-ion battery with a significantly lower total weight.

Aluminium-air batteries are primary cells, i.e., non-rechargeable. Once the aluminium anode is consumed by its reaction with atmospheric oxygen at a cathode immersed in a water-based electrolyte to form hydrated aluminium oxide, the battery will no longer produce electricity. However, it is possible to mechanically recharge the battery with new aluminium anodes made from recycling the hydrated aluminium oxide. Such recycling would be essential if aluminium-air batteries are to be widely adopted.

Aluminium-powered vehicles have been under discussion for some decades. Hybridisation mitigates the costs, and in 1989 road tests of a hybridised aluminium-air/ lead-acid battery in an electric vehicle were reported. An aluminium-powered plug-in hybrid minivan was demonstrated in Ontario in 1990.

In March 2013, Phinergy released a video demonstration of an electric car using aluminium-air cells driven 330 km using a special cathode and potassium hydroxide. On May 27, 2013, the Israeli channel 10 evening news broadcast showed a car with Phinergy battery in the back, claiming 2,000 kilometres (1,200 mi) range before replacement of the aluminum anodes is necessary.

The anode oxidation half-reaction is Al + → + 3e − -2.31 V.

The cathode reduction half-reaction is + + 4e − → +0.40 V.

The total reaction is 4Al + + → + 2.71 V.

About 1.2 volts potential difference is created by these reactions and is achievable in practice when potassium hydroxide is used as the electrolyte. Saltwater electrolyte achieves approximately 0.7 volts per cell.

Aluminium as a "fuel" for vehicles has been studied by Yang and Knickle. In 2002, they concluded:

The Al/air battery system can generate enough energy and power for driving ranges and acceleration similar to gasoline powered cars...the cost of aluminium as an anode can be as low as US$ 1.1/kg as long as the reaction product is recycled. The total fuel efficiency during the cycle process in Al/air electric vehicles (EVs) can be 15% (present stage) or 20% (projected), comparable to that of internal combustion engine vehicles (ICEs) (13%). The design battery energy density is 1300 Wh/kg (present) or 2000 Wh/kg (projected). The cost of battery system chosen to evaluate is US$ 30/kW (present) or US$ 29/kW (projected). Al/air EVs life-cycle analysis was conducted and compared to lead/acid and nickel metal hydride (NiMH) EVs. Only the Al/air EVs can be projected to have a travel range comparable to ICEs. From this analysis, Al/air EVs are the most promising candidates compared to ICEs in terms of travel range, purchase price, fuel cost, and life-cycle cost.

Technical problems remain to be solved to make Al-air batteries suitable for electric vehicles. Anodes made of pure aluminium are corroded by the electrolyte, so the aluminium is usually alloyed with tin or other elements. The hydrated alumina that is created by the cell reaction forms a gel-like substance at the anode and reduces the electricity output. This is an issue being addressed in the development work on Al-air cells. For example, additives that form the alumina as a powder rather than a gel have been developed.

Modern air cathodes consist of a reactive layer of carbon with a nickel-grid current collector, a catalyst (e.g., cobalt), and a porous hydrophobic PTFE film that prevents electrolyte leakage. The oxygen in the air passes through the PTFE then reacts with the water to create hydroxide ions. These cathodes work well but they can be expensive.

Traditional Al-air batteries had a limited shelf life because the aluminium reacted with the electrolyte and produced hydrogen when the battery was not in use-although this is no longer the case with modern designs. The problem can be avoided by storing the electrolyte in a tank outside the battery and transferring it to the battery when it is required for use.

These batteries can be used, for example, as reserve batteries in telephone exchanges and as backup power sources.

# data[].attributes.attachment_link.description
Aluminium-air batteries (Al-air batteries) produce electricity from the reaction of oxygen in the air with aluminium. They have one of the highest energy densities of all batteries, but they are not widely used because of problems with high anode cost and byproduct removal when using traditional electrolytes.

# data[].attributes.body
Uses of electrolysis:

· Production of chlorine and sodium hydroxide

· Production of sodium chlorate and potassium chlorate

· Production of perfluorinated organic compounds such as trifluoroacetic acid by the process of electrofluorination

· Production of electrolytic copper as a cathode, from refined copper of lower purity as an anode.

· Production of oxygen for spacecraft and nuclear submarines.

· Production of hydrogen for fuel, using a cheap source of electrical energy.

· The making of chlorine and caustic soda for chlor-alkali industry.

· Hair removal for aesthetic purposes. It works by destroying the hair follicle producing the unwanted strand of hair.

· Separating water molecules into their base elements of hydrogen and oxygen. This technique is useful in harsh or restricted environments.

· The creation of substances s Sodium chlorate, potassium chlorate, chlorine and aluminium all are produced via electrolysis.

· Electroplating is commonly used for various purposes such as: the bumpers of cars are chromium-plated and water taps being plated with nickel or chromium to protect them from corrosion; ‘tin’ cans being only iron plated with tin to prevent rusting; a ‘silver’ spoon being electroplated for decoration.

by Afifah

# data[].attributes.body
Notice: Welcome STK and SMKDHHY apps users!!
You are encouraged to ask any questions on chemistry here.

Students and teachers, can give respond to the questions asked. Urgent answer, just call the contact button in the apps

# data[].attributes.headline
haloalkane have two type of nucleophilic substitution sn 1 and sn 2 

# data[].attributes.subject
haloalkane have two type of nucleophilic substitution sn 1 and sn 2 

# data[].attributes.body
sn 2=primary haloalkane undergo hydrolysis by sn 2 mechanism

in this reaction, the halogen atom will repel the OH- ion and the ion will attack the carbon atom from the back . an activated complex will be formed.

sn 1= tertiary haloalkane undergo hydrolysis by sn 1 mechanism because the protection of three big alkyl group that protect the carbon atom from nucleophile

by jia hau

# data[].attributes.body
Haloalkanes react with NaOH to form alcohol(-OH)
Haloalkanes react with KCN to form nitriles(-CN)
Haloalkanes react with NH₃ to form amine(-NH₂)
Sn is the nucleophilic substitution when its nucleophile in haloalkanes is replace by other nucleophile. Exp: R-CH₂Br +NaOH= R-CH₂OH + NaBr

# data[].attributes.body
Haloalkanes will undergoes neuclophile substitution in reactions. Haloalkanes only got 4 reactios :
Hydrolysis haloalkanes
Formation of nitriles
Formation of amines
Elimination reactions of haloalkanes
Mechanism of nucleophilic substitution ofhaloalkanes is Sn1 and Sn2

# data[].attributes.headline
Haloalkane has 4 reactions which are hydrolysis, formation of nitrile , formation of amines and elimition reaction. Alkene can form haloalkane by substitute the halogen.Hydrolysis will form alcohol, reagent in formation of nitrile is CN, reagent in formation of amines is NH3, reagent in elimination is ethanolic sodium hydroxide

# data[].attributes.subject
Haloalkane has 4 reactions which are hydrolysis, formation of nitrile , formation of amines and elimition reaction. Alkene can form haloalkane by substitute the halogen.Hydrolysis will form alcohol, reagent in formation of nitrile is CN, reagent in formation of amines is NH3, reagent in elimination is ethanolic sodium hydroxide

# data[].attributes.body
How to relate alkaline hydrolysis to sn2 ?

# data[].attributes.headline
Please write whatever you want write about sem 3 here

# data[].attributes.subject
Please write whatever you want write about sem 3 here

# data[].attributes.attachment_link.title
STPM Sem 3 / A-Level : Organic Chem: Aromatic Compound - YouTube

# data[].attributes.attachment_link.description
STPM Sem 3 / A-Level : Organic Chem: Aromatic Compound - 04