In a chemical reaction, new products are formed from

the reactants. How can you tell this has happened?

There are a few clues you can look out for that might

mean a reaction has taken place.

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In some cases, a gas is given off, or heat is produced. 

Sometimes you can see a color change or you can 

check a chance in the pH using an indicator.

Some reactions between two liquid reactants can

produce a solid precipitate.

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Today, we will watch videos about different reactions taking place and we will identify how we can tell a reaction is happening.

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In each point you will watch the video of a reaction, you must click on the image to go to the link of the video:

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1.  Watch the following video (you will only need to watch some specific parts)

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a) Write the word equation for this reaction

b) Write the chemical equation

c) At the end of the reaction, what was the 

clue or change you could easily identify to

know that a reaction took place?

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2. Watch the video. You can use the information from last the class about reactions with acids to have the formulas.

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a) Write the 2 word equations (One for Mg,

one for Zn) (They are 2 different rxns)

b) Write the chemical equations.

c) How can we know that a reaction has

taken place?

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3. Watch the video about Potassium and water

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a) Write 3 changes that happen during the reaction

b) Write the word and chemical formulas

c) Investigate why is Potassium called an alkali

metal, what does this mean?

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4. Sodium hydroxide and hydrochloric acid react to produce sodium chloride and water. Watch the video and answer the questions:

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a) Write the chemical equation

b) What happens to the sodium hydroxide

when he adds the phenolphthalein?

c) What happens when he mixes both 

reactants?

d) Investigate what is the name of a reaction

in which an alkali neutralizes an acid?

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5. Silver nitrate and calcium chloride react to form silver chloride and calcium nitrate. Watch the video and answer: (the rxn starts in minute 2:25)​

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a) Write the chemical equation (no video

needed for this)

b) What is the change that allows you

to know that a reaction took place?

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6. Using what you learnt during the previous classes, create a word search game (sopa de letras) with clues to find the following terms:​

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Element                    Products

Chemical                  Precipitate

Physical                    Rusting

Mixture                     Solution

Reactants                Reaction

Compound              Combustion

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Today we will work on some topics that are evaluated in the Cambridge exams and that are closely related to chemical reactions.

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For this, we will solve the following worksheet individually in a piece of paper and at the end of the class you have to hand it in to the teacher

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