Chemical Reactions

Question 1

What is combustion?

Answer 1

Combustion is a reaction that needs oxygen, heat, and fuel to occur. Combustion is an exothermic reaction that gives off heat.

Question 2

How can combustion be used in a helpful way?

Answer 2

Provide us with with heat for staying warm and cooking, generate electricity, etc.

Question 3

How can combustion be prevented when harmful?

Answer 3

Combustion can be prevented by spreading out materials that could build heat and combust.

Question 4

Write a word equation for combustion.

Answer 4

Fuel + heat + oxygen -> carbon dioxide + water

Question 5

What is corrosion?

Answer 5

Corrosion is a slow version of combustion that forms another compound, and occurs when metals are exposed to water, air, and other substances. A common reaction of corrosion is when metal rusts.

Question 6

How can corrosion be used in a helpful way?

Answer 6

Corrosion can be helpful in some cases as it adds a protective layer, protecting the insides of a metal.

Question 7

How can corrosion be prevented when harmful?

Answer 7

Corrosion can be prevented by keeping metals dry and clean, or even heat treating metal or adding different elements to make it corrosion resistant, such as stainless steel that does not rust.

Question 8

Write a word equation for corrosion.

Answer 8

Iron + Oxygen + water -> Iron oxide.

Metal + oxygen + water -> metal oxide.

Question 9

What is an indicator and what do we use them for in chemistry?

Answer 9

An indicator is a substance that changes colour when mixed with another substance to show what its pH level is.Typically, red tones mean an acid, green is neutral, and blue tones are base, however this depends on which indicator.

Question 10

What are the different types of indicator?

Answer 10

Litmus paper, universal indicator, Bromothymol blue, Thymol blue, Phenolphthalein.

Question 11

Are all indicators the same?

Answer 11

Some indicators, such as litmus paper, are a paper that change colour, whereas other indicators, such as universal indicator, or even cabbage juice, are liquids that change colours.

Question 12

Know what is neutral, weakly acidic, strongly acidic, weakly basic and strongly basic.

Answer 12

The lower the number, the stronger an acid it is. A weak acid has a pH level of around 4-6, a neutral is a 7, strong bases have a level of about 11-14, and weak bases are around an 8-10.

Question 13

What are the pHs of some common household chemicals like what we tested in class?

Answer 13

Soap has a pH level of 8-10, vinegar is 3, baking soda is 9, bleach is 13, and lemon is about a 2.

Question 14

word equation for a neutralization reaction

Answer 14

Base + Acid -> a salt + water.

Question 15

acids and carbonate reactions

Answer 15

Acid + carbonate -> a salt + water + carbon dioxide.

Question 16

acids and metal reactions

Answer 16

Acid + metal -> a salt + hydrogen gas

Question 17

Compare and contrast acids and bases

Answer 17

Acids have a sour taste, turn blue litmus paper red, are low on the pH scale, and are neutralized by bases. Bases can corrode, have a bitter taste, turn red litmus paper blue, have a soapy, slimy feel, are high on the pH scale, and are neutralized by acids.

Question 18

Chemical change

Answer 18

When a chemical change occurs, a few things can happen. Either a gas can be released, an odor can be formed, there can be a change in colour, and more. But every time, a new substance is formed, and chemical bonds are broken and then reformed.

Question 19

physical change

Answer 19

In a physical change, the main reaction is for a change of state of matter to occur, no new substance is made.

Question 20

Revise why an atom has an overall neutral charge.

Answer 20

All atoms have an overall neutral charge as they have equal protons to electrons.

Question 21

Revise what the subatomic particles are and where they are found and what charge they have

Answer 21

Both the protons and then neutrons are found in the nucleus, with protons having a positive charge, and neutrons having a neutral charge. Electrons are found outside the nucleus, in the electron shell, and they have a negative charge

Question 22

Revise how to determine how many protons and how many neutrons a particular atom has

Answer 22

The number of protons is shown in the atomic number, the number at the bottom of a chemical symbol. To work out the number of neutrons, you need to subtract the number of protons from the mass number (the other number at the top of a chemical symbol).

Question 23

How to write the symbol for an element which shows its atomic number and mass number

Answer 23

Mass number up, atomic number down, chemical symbol to the right.