3E 2.4 Fire triangle - reagens

• Scheikunde
• Middelbare school
• havo, vwo
• Leerjaar 3

3E Chemistry task week 50-51

• You can name the three conditions for combustion.
• You can use the fire triangle to explain how to extinguish a fire.
• You know what a reagent is.
• You can explain how to demonstrate the presence of hydrogen, oxygen, water, carbon dioxide and sulfur dioxide.

This does not belong in the fire in the triangle:

fuel

oxygen

temperature higher than the ignition temperature

food

heat

cold

melting

density

How to extinguishing a fire

You now know which three factors are necessary the get a fire started.
If you want to extinguish a fire, you must remove one (or more) of these factors.

For each situation, you can examine which factor is easiest to remove and therefor determine which extinguishing method can be used.

For example, in the event of a fire caused by a gas leak, it is wise to first close the gas tap (remove fuel).

Look at the sentences below about extinguishing a fire.

Drag the sentences to the side of the triangle that you have to remove.

Close the gas tap.

Extinguish a paper fire with water

Wrapping someone in a fire blanket.

Blow out a lighter.

Place the lid on the deep fryer.

Extinguish a gasoline fire with foam

A reagent is a substance that reacts in a characteristic, observable manner (sound or color) with the substance you want to demonstrate.

A reagent needs two meet two requirements:

Selective: the reagent only reacts to one (or little) substance(s)

Sensitive: little amount is required of both the reagent as 
                    the substance to be detected. 

There are some reagents you need to know about.

Reagent (plural: reagents)

NOTE

& LEARN

Copy this scheme in your chemistry notebookschrift 

show	reagent/method	Observation
water
	limewater
sulfur dioxide
	glowing splint
	flame	you hear a characteristic 'pop'

NOTE

& LEARN

You must complete this table with the help of the following slides.

Watch the above (Dutch) videos to complete your table further. Good luck.

Practise makes perfect.

Your table should be completely filled in.

Answer the following questions to see if your knowledge about reagents is complete enough. 

Improve your schedule if necessary.

White copper sulphate is a ... to demonstrate the presence of ... .

1. reagent, carbon dioxide
2. reagent, hydrogen
3. reagent, water
4. reagent, oxygen

A reagent that detects only one or very few different substances is called ....

1. sensitive
2. sensible
3. selective
4. obvious

Which statements are true?
1) A reagent must be sensitive and therefore must react
with a little bit of the substance
2) A reagent must be selective and therefore it must only react
with itself

1. A and B are true
2. A is true, B is not true
3. A is not true, B is true
4. A and B are not true

The presence of oxygen can be shown by:

1. collect the gas in a test tube and hold the opening near a flame you hear a 'pop'
2. collect the gas in a test tube and hold a glowing splint in the test tube, the splint will glow brighter

The 'pop' that you hear is evidence of the presence of

1. carbon dioxide
2. hydrogen
3. oxygen
4. water

The flask contains lime water. A second substance is sucked through the lime water. Which substance can you detect with lime water?

1. Water
2. Carbon dioxide
3. Oxygen
4. None of the three options

You can show the presence of carbon dioxide with lime water. What happens to the limewater when it reacts with carbon dioxide?

1. It's going to solidify
2. It becomes yellow and cloudy
3. It becomes a clear liquid
4. It becomes cloudy white

What is the reagent of SO2?

1. iodine solution
2. white copper sulphate
3. lime water
4. starch

Which reagent is used to demonstrate:

oxygen

carbon dioxide

water

hydrogen

sulfur dioxide

clear lime water

white copper sulphate 

glowing splint

flame

iodine solution

What observation do you do when demonstrating:

oxygen

carbon dioxide

water

hydrogen

sulfur dioxide

clear colorless liquid turns white cloudy

white solid becomes a blue solid

will glow brighter

flame

clear yellow liquid becomes clear colorless liquid

All done?!

Please upload a picture of your reagent tabel at the 'opdracht' in google classroom.