weak bitter corrosive base digest hydrochloric strong stomach hydroxides litmus Less than soapy sour More than vinegar An acid is a substance with a pH of __________ ________7. It will turn universal indicator red if they are ___________, and orange or yellow if it is weak. Acids often taste _________ and many acids can be _________________ if you touch them. Lemon juice and _________________ are examples and _________________ acid is a very strong acid found in your ___________. You can use blue_________________ paper to determine if something is acid or not because the acid will turn the paper red. Bases are usually metal oxides or metal __________ . For example, copper oxide and sodium hydroxide. Bases feel _________________ when you touch them and taste _________________. Many household cleaners are bases. Some bases can even dissolve hair and food, which makes them ideal for clearing clogged drains. Alkalis: are soluble ________. Have a pH of __________ _________7. They turn red litmus paper blue and turn universal indicator dark blue or purple if they are strong, and blue-green if they are _________. Sodium hydroxide is an example. less than strong sour corrosive vinegar hydrochloric stomach litmus hydroxides soapy bitter bases more than weak

Which is better, universal indicator or red cabbage indicator? What is an indicator? Which is better, universal indicator or red cabbage indicator? Strong Acid Weak Acid Neutral Weak alkali Strong alkali

If you mixed an acid with an alkali they would cancel each other out? True or False? If you mixed an acid with an alkali they would cancel each other out? TRUE FALSE

Neutralisation

What is the pH?

You can think of the pH Scale a bit like a see-saw

Neutral is not acid, not alkali It is balanced

Acids can be made neutral HOW?

What is neutralisation? The chemical reaction between an acid and an alkali is called neutralisation. acid alkali a salt water What happens to the pH value of the reaction mixture during neutralisation? The pH value of the reaction mixture becomes closer to 7.

You will need: A conical flask 2 measuring cylinders (need to be able to measure 15ml) Universal indicator Safety glasses Hair tied back Stood up seats and bags under desk,

What to do Measure 10ml of Hydrochloric acid using a measuring cylinder. Put into beaker. Put in 5 drops of Universal Indicator (RED) Add Sodium Hydroxide (alkali) drop by drop using a pipette until it goes GREEN WHAT DO YOU DO IF IT GOES BLUE/PURPLE????

Homework: Due in Thursdays lesson. Create a poster that shows 3 different real life examples of neutralisation. Explain what is happening in the neutralisation reaction and why it is useful. Use pictures to explain the 3 types. Use equations to explain what neutralisation is.

Starter: In your books, describe what an indicator does, giving examples.

What is in the beaker now??? You added 2 chemicals together, and they cancelled each other out. You have made what scientists call a ‘salt’ But the salt is dissolved in a liquid – water To get the salt out what can we do?

Word search

Answers ACID LITMUS ALKALI INDICATOR SALT CORROSIVE WATER CAUSTIC ALKALINE NEUTRALIZE ACIDIC TOXIC

The hard bit….. ACID + ALKALI  SALT + WATER Copy these 2 equations down into your books. Label the reactants, products, and salt.

Now complete the equations below…. sulfuric acid + potassium hydroxide → hydrochloric acid + ammonium hydroxide → sulfuric acid + ammonium hydroxide → hydrochloric acid + potassium hydroxide →

Different acids make different salts Hydrochloric Chlorides Sulphuric Sulphates Nitric Nitrates Phosphoric Phosphates

Reactions of acids with bases A chemical reaction happens if you mix together an acid and a base. The reaction is called neutralisation, and a neutral solution is made if you add just the right amount of acid and base together. Metal oxides and metal hydroxides Metal oxides and metal hydroxides are two types of bases. For example copper oxide and sodium hydroxide. Here are general word equations for what happens in their neutralisation reactions with acids. metal oxide + acid → a salt + water metal hydroxide + acid → a salt + water Notice that a salt and water are always produced. The mixture usually warms up a little during the reaction, too. The exact salt made depends upon which acid and base were used. Carbonates and hydrogen carbonates Carbonates and hydrogen carbonates are two other types of base. They also make a salt and water when we neutralise them with acid. But this time we get carbon dioxide gas too. The reaction fizzes as bubbles of carbon dioxide are given off. This is easy to remember because we see the word 'carbonate' in the chemical names. These are the general word equations for what happens: acid + metal carbonate → a salt + water + carbon dioxide acid + metal hydrogen carbonate → a salt + water + carbon dioxide

Neutralizing stings A bee sting is acidic. A wasp sting is alkaline. Why can bicarbonate of soda (pH 9) be used to treat a bee sting? Why can vinegar (pH 3) be used to treat a wasp sting?

Neutralizing soil Soils in different places can be acidic, alkaline or neutral. Many plants do not grow well in acidic soil. Why do farmers test soil to check the pH? Farmers often add an alkali to acidic soil to make their plants grow better. How does the alkali help to treat the acidic soil?