ACIDS AND BASES

Alkali

-A base that dissolves in water is called an alkali. -Solution it forms is known as an alkaline solution.

Example of dilute acid

-Contains a large proportion of water -Has less acid particles. e.g 0.1M HCl

Example of concentrated acid

-Has a lot of acid particles, e.g10M HCl

Example of weak acid

-Lose only a few H+ ions (not very easily) e.g Vinegar (ethanoic acid or acetic acid) -(CH3COOH) -produces hydrogen ions or hydroxide ions to a small extent; concentrated: not much water in it;

What colour are red and blue litmus paper in acid?

-Red for blue paper -Nothing for red -If Universal Indicator turns pink.

Example of a strong acid

-Strong acids lose their H+ very easily and are corrosive -Produces hydrogen ions (acid) to a large extent or hydroxide ions (base) to a large extent; -Nitric Acid (HNO3): Making fertilisers, dyes and explosives

Example of a strong base

-Strong bases produce lots of OH- ions -Sodium hydroxide (caustic soda) -NaOH -Producing soap -Paint stripper -Drain and oven cleaner

How would you test to see if a substance was a base?

-Test with blue litmus paper and see if it turns red -If Universal Indicator turns pink.

How would you test to see if a substance was an acid?

-Test with blue litmus paper and see if it turns red -If Universal Indicator turns pink.

Properties of bases?

-are caustic -have a soapy, slimy feel -turn red litmus paper blue (shown in Figure 2.3.4) -have a bitter taste -conduct electricity -are neutralised by acids, producing water and a salt.

What are some properties of acids?

-are corrosive. -have a sour taste (think of the taste of vinegar) -turn blue litmus paper red -react with some metals, releasing hydrogen gas and leaving a salt behind -conduct electricity -are neutralised by bases, producing water and a salt.

Example of a dilute base

0.1M NaOH

Example of concentrated base

10M NaOH

What is a base?

A base is a chemical substance that accepts hydrogen ions easily and produces hydroxide ions (OH-).

What colour does Universal Indicator turn in base?

Blue/dark green

What pH do acids have at 25 degrees Celsius?

More than 7

What pH do bases have at 25 degrees Celsius?

More than 7

What colour does Universal Indicator turn in acid?

Pink

What colour are red and blue litmus paper in base?

Red litmus stays red Blue litmus turns red

What is an acid?

Substance that releases hydrogen ions (H+) into an aqueous solution (containing water). e.g hydrochloric acid that's in your stomach and the ethanoic acid (acetic acid) found in vinegar.

What is pH?

The concentration of hydrogen ions (H+) in a solution is measured using the pH scale. In an acidic solution, there are more hydrogen ions than hydroxide (OH-) ions. In contrast, an alkaline solution has more hydroxide ions than hydrogen ions. Pure water is neither an acid nor a base. It's neutral, having equal numbers of hydrogen and hydroxide ions. It has a pH of 7. acids have a pH less than 7, while bases and alkaline solutions have a pH greater than 7.

Strenght of acid

The strength of an acid depends on how many hydrogen ions are released

What does a base produce when it reacts with an acid?

acid + base -> salt and water

What does an acid produce when it reacts with a base?

acid + base -> salt and water

What does an acid produce when it reacts with a carbonate or bicarbonate?

acid + carbonate -> salt + water + carbon dioxide

What does an acid produce when it reacts with a metal?

acid + metal -> salt and hydrogen gas

Example of weak base

bases only produce a few OH- Ammonia: NH3 (HOUSEHOLD CLEANER)