Chemistry

Define the first theory of bases

Known as the Bronsted Lowry theory, is states a base is calssified as any substance that is a proton acceptor (therefore the substances can not be positively charged as same charges repel).

What are the limitations of the Bronsted Lowry theory of bases?

There will have to be a transferrable proton present in a chemical reaction.

What is the second theory of bases?

Known as the Arrhenius theory, it states that bases are identified by their ability to release hydroxide ions (OH⁻) when dissolved in water.

What are the limitations of the Arrhenius theory of bases

It only applies to chemical reactions including an aqueous solution (a solution where water is the solvent).

Define the third theory of bases

Known as the Lewis theory, it states a base is any form of a substance that is capeble of loosing an electron via transfiguration.

What are the limitations of the Lewis theory of bases?

It lacks in clear mathematical scale to measure the strength of a base, and does not imply the speed of the chemical reaction of the base.

What are the physical properties of bases?

Tastes bitter, slippery/soapy texture, can conduct electricity when in an aqueous solution and ph dyes: Turns blue with litmus paper turning blue (in ph 7.1-7.9), bromothymol turns from yellow in acidic conditions to vivid blue in basic solutions and red cabbage turns from red to green, yellow or blue depending on the exact ph level.

What are basic solutions?

Aqeous solutions with a ph level. of 7-14

What is an aqeous solution?

A solution where water (including salt, sugar water) is the solvent.

What is a ph dye indicator?

A substance added to a solution to identify the ph level of the solution, which is indicated by colour change.

What are the chemical properties of bases?

Neutralises acids (because of its alkaline nature) and produces salt + water in chemical reactions, highly corrosive (due to highly alkaline nature) and high concentration of hydroxide ions (OH⁻) that decompose protein molecules and when heated with ammonium salts, its emits ammonium gas (NH₃) which has a strong, choking smell.

When bases are disolved in water what type of solution is made?

Aqeous solution (a solution where what is the solvent\)

How do bases make a solution alkaline/basic?

They release hydroxide ions. This makes the solution basic or alkaline because hydroxide ions are active species in alkaline solutions.

What does it mean if an atom, molecule or particle has an active species to something?

It means that the particle is highly reactive and short lived to form that something.

Define an acid

A substances that is capable of donating a proton.

How are acid solutions formed?

When an acid is placed in water, is dissociates, breaking apart and releasing hydrogen ions (protons). These hydrogen ions (H⁺), then bind with the water atoms (H₂O) to form hydronuim ions (H₃O⁺). The concentration of these hydronuim ions is what determines the acidity of the solution.

What does 7 indicate on the ph scale?

Neutral

What does 1-6.9 indicate on the ph scale?

Acidic

What does 7.1-14 indicate on the ph scale?

Alkaline

What are the types of acids?

Carbonic, Sulfuric, Binary, Oxyacid, Strong and weak acids.

What is the chemical equation to make carbonic acid?

CO₂ + H₂O →H₂CO₃

What is carbonic acid?

A type of acid that is formed when carbon dioxide (a soluble gas) dissolves in water. This type of acid naturally increases the acidity in rain.

What is the chemical equation for sulfuric acid?

SO₂ + H₂O→SH₂SO₃

What is sulfuric acid?

A type of acid that is formed by sulfur dioxide- a gas produced by fossil fuels being burnt- reacts with water in the atmospheric air. This creates a sulfurous acidic gas that heavily contributes to acid rain

What is the chemical equation for binary acid?

H₂+(non-metallic element)₂→2H(non-metallic element) acid

What are binary acids?

Types of acids that are formed by hydrogen gas reacting with a non-metal (such as a halogen). This causes a chemical reaction that forms an aqeuos solution acid.

How are strong acids formed?

When an acid completely ionizes in water (splits apart), which causes a release of a high concentration of hydrogen ions (protons).

How are weak acids formed?

When acid is placed in water and only partially ionizes, meaning that some hydrogen ions attach to water molecules, whilst the majority of hydrogen ions remain whole and don’t engage with the water molecules.

What does an acid + a metal make?

Acid + metal →a salt + hydrogen gas

Why does an acid + a metal →a salt +hydrogen gas

In this reaction, the metal transfers it’s outer most shell electrons to the hydrogen ions (protons) in the acid. As these are positively charged ions, the addition of a negatively charged particle (in this case the electrons being transferred) would make a neutral charge, therefore neutralising the acid. This makes the acid turn to the product hydrogen gas (H₂). This evaporates into the atmospheric- which is why the law of conservation of mass seemingly does not apply, as the mass of the hydrogen gas is lost. Simultaneously, due to displacement, the more reactive metal want to have an electrical charge, more than hydrogen. So the metal strips the protons from the hydrogen ions that remain in the acid to form a metal salt.

What does an acid + a base (metaloxide/hydroxide) make?

Acid + base (metaloxide/ hydroxide) →a salt + water

Why does an acid + a base (metaloxide/hydroxie) →a salt + water

This reaction is known as neutralization. Following the Bronsted Lowry theory of bases, the base (which contains oxide or hydroxide) acts as a protons acceptor. Therefore the acid’s hydrogen ions (being positively charged protons) and the bases hydroxide ions (being negatively charged) attract. Alongside this, as bases have an alkaline nature, and acid have a more acidic nature when both substances combine they form a neutral stable substance, which in this case is water. A hydroxide ions (OH⁻) + hydrogen ions (H⁺) → water (H₂O). The salt if formed bt the reaming ions in both the base and acid forming ionic bonds to form the salt (an ionic compound).

What does an acid + a carbonate make?

Acid + carbonate →a salt + carbon dioxide + water

Why does an acid + a carbonate →a salt + water + carbon dioxide

Following the Bronsted Lowry theory of bases, bases act as proton acceptors.This reaction occurs when in an aqeous solution (a solution where water is the solvent). As the carbonate is a base, it means that in this chemical reaction the acid will transfer its hydrogen ions (protons) to the carbonate compound- that is made up of CO⁻²₃ ions. The transfiguration of protons forms carbonic acid (H₂CO₃)- a highly unstable substance- as the positively charged hydrogen ions attract to the negatively charged carbonate ions. Although, carbonic acid is so chemically unstable it begins to expirence decomposition as it can not retain stability in water. This causes a rearragement of the molecular formation of carbonic acid, forming water and carbon dioxide. As this reaction occurs, the remaining ions being dissolved into the aqeous solution are free moving ions. The product salt is made from evaporating the water, and leaving the ions to bond together to make solid crystal salts.

What is step 1 to complete a neutralization reaction?

Pour diluted acid into a beaker, and gently heat the beaker with a bunson burner.

What is step 2 to complete a neutralization reaction?

Repeatingly, add in your insoluble base into your heating beaker. The insoluble base will frequently dissapear, as it is reacting with the diluted acid to form an aqueous solution.

What is step 3 to complete a neutralization reaction?

When the insoluble base is no longer dissapearing, stop adding the base. At this point the acid and base solution (aqueous solution) has become saturated. When this occurs, filter excess insoluble base using a filter paper and filter funnel. The liquid that passes through is the dissolved form of the soluble salt that is a product of the neutralization reaction.

What is step 4 to complete a neutralization reaction?

In order to solidify the liquid salts firstly heat the filtered solution gently. To do this use awater bath or electric heater to evaporate some of the water. Don’t use a bunsen burner as this will potentially damage the salts.

What is step 5 to complete a neutralization reaction?

After you see some crystals forming, remove the solution from the heating apprehentus (water bath or electric heater) and leave it to cool. This will increase the rate of crystalisation.

What is step 6 to complete a neutralization reaction?

Finally, filter the crystals out of the remaining solution, using a filter paper and filter funnel. Then dry them by placing them near a window. Then you have your salts.

What are the physical properties of acids?

Taste sour, acids turn blue with litmus paper turns red and turns phenolphthalein colourless, can be solids, liquids or gases, are highly soluble and can conduct electricity in aqueous solutions.

What are the chemical properties of acids?

Strong acids are highly corrosive, acid + metal →hydrogen (gas) + a salt, acid + base →water + a salt (neutralization), acid + carbonate →water + a salt + carbon dioxide, ph level 1-6.9, high melting and boiling points.