Science

1. Science Kaltham Al-Kuwari 7D

2. Which acids do we normally find in the laboratory? Diluted Acids and Concentrated Acids. Diluted Acids are labeled with the warning symbol for “irritant”. This means that if the Acid makes contact with your skin, it will be red and blistered. You must wash your skin with plenty of water as soon as possible or else your skin will feel like it is burning. In class, we are unlikely to use Concentrated Acids but your teacher might use it while presenting/showing an experiment. This is because Concentrated Acids are “corrosive” which means they can attack metals and destroy skin if spilled.

3. Which acids do we normally find in the home? Some acids you might find at home are Carbonic Acid in fizzy drinks, Tannic Acid in tea and Ascorbic Acid which is Vitamin C, found in fruit and vegetables. Vinegar > Ethanoic Acid Fizzy Drinks > Carbon Dioxide Tea > Tannic Acid Vitamin C > Ascorbic Acid Lemons > Citric Acid

4. What is a Base? Bases are substances that react with acids neutralise with them. They are usually metal oxides, metal hydroxides, metal carbonates or metal hydrogen carbonates. Many Bases are insoluble which means they do not dissolve in water. If a base does dissolve, we call it an alkali.

5. What is an Alkali? Alkali is a base that does not dissolve in water. Here are two examples: 1- Copper oxide is a base because it will react with acids and neutralise them, but it is not an alkali because it does not dissolve in water. 2- Sodium hydroxide is a base because it will react with acids and neutralise them. It's also an alkali because it dissolves in water. All alkalis are bases, but only soluble bases are alkalis.

6. Which bases do we normally find in the laboratory? You will have used some strong bases and alkalis at school, such as sodium hydroxide solution. Like acids, their bottles are labelled with the warning symbol for “irritant”. Alkalis feel soapy when they get on your skin, so it is easy to tell when you have had an accident and must wash your hands. Concentrated alkalis are corrosive. They can attack metals and destroy skin if spilled. They are just as dangerous as concentrated acids, but many people do not realise this.

7. Which bases do we normally find in the home? Bases react with oils and fats, so they are often used in strong household cleaners. Ammonia is also commonly used in cleaners. Ammonia can be recognized by its choking smell. It is wise to wear gloves when using these substances, otherwise they will react with your skin and burn it. Weak bases and alkalis are found in toothpaste, antacid tablets (to help cure an upset stomach) and baking powder.