Post by Na9er on Oct 22, 2012 13:26:10 GMT -5
Acids have a variety of applications for the industrial and domestic markets. Acids can be neutralised using an alkali or base and used to make salts.
What are acids?
All acids:
Indigestion Remedies
Hydrochloric acid is used in the body to help digestion and kill bacteria.
However too much acid can cause indigestion and we use indigestion remedies to neutralise excess acids.
An indigestion remedy contains a base such as magnesium hydroxide, which reacts to form a neutral compound and raises the pH of the stomach.
Neutralisation
Metal hydroxides
Metal hydroxides, such as sodium hydroxide, usually dissolve in water to form clear, colourless solutions. When an acid reacts with a metal hydroxide, the only products formed are a salt plus water. Here is the general word equation for the reaction:
acid + metal hydroxide → a salt + water
You usually observe these things during the reaction:
Metal oxides
Some metal oxides, such as sodium oxide, dissolve in water to form clear, colourless solutions. Many of them are not soluble in water, but they will react with acids. Copper oxide is like this. When an acid reacts with a metal oxide, the only products formed are a salt plus water. Here is the general word equation for the reaction:
acid + metal oxide → a salt + water
You usually observe the same things during the reaction that you observe with metal hydroxides.
Metal carbonates
Although sodium carbonate can dissolve in water, most metal carbonates are not soluble. Calcium carbonate (chalk, limestone and marble) is like this. When an acid reacts with a metal carbonate, the products formed are a salt plus water, but carbon dioxide is also formed. Here is the general word equation for the reaction:
acid + metal carbonate → a salt + water + carbon dioxide
You usually observe bubbles of gas being given off during the reaction. You can show that the gas is carbon dioxide by bubbling it through limewater, this turns cloudy white when it reacts with carbon dioxide.
What are acids?
All acids:
- Have a low pH (1-6) – the lower the number the stronger the acid
react with bases to form neutral compounds. - Are corrosive when they are strong.
- Are an irritant when they are weak.
Indigestion Remedies
Hydrochloric acid is used in the body to help digestion and kill bacteria.
However too much acid can cause indigestion and we use indigestion remedies to neutralise excess acids.
An indigestion remedy contains a base such as magnesium hydroxide, which reacts to form a neutral compound and raises the pH of the stomach.
Neutralisation
Metal hydroxides
Metal hydroxides, such as sodium hydroxide, usually dissolve in water to form clear, colourless solutions. When an acid reacts with a metal hydroxide, the only products formed are a salt plus water. Here is the general word equation for the reaction:
acid + metal hydroxide → a salt + water
You usually observe these things during the reaction:
- There is a temperature rise
- The pH of the reaction mixture changes
Metal oxides
Some metal oxides, such as sodium oxide, dissolve in water to form clear, colourless solutions. Many of them are not soluble in water, but they will react with acids. Copper oxide is like this. When an acid reacts with a metal oxide, the only products formed are a salt plus water. Here is the general word equation for the reaction:
acid + metal oxide → a salt + water
You usually observe the same things during the reaction that you observe with metal hydroxides.
Metal carbonates
Although sodium carbonate can dissolve in water, most metal carbonates are not soluble. Calcium carbonate (chalk, limestone and marble) is like this. When an acid reacts with a metal carbonate, the products formed are a salt plus water, but carbon dioxide is also formed. Here is the general word equation for the reaction:
acid + metal carbonate → a salt + water + carbon dioxide
You usually observe bubbles of gas being given off during the reaction. You can show that the gas is carbon dioxide by bubbling it through limewater, this turns cloudy white when it reacts with carbon dioxide.