Chemistry

Question 1

A bee sting contains acids. Explain why some people use an alkali such as baking soda on bee stings.

Answer 1

You do this because adding an alkali will neutralize the acidity of the bee sting.

Question 2

What is the difference between corrosion and rusting?

Answer 2

Corrosion refers to any reaction with oxygen at the surface of a metal. Rusting refers to the corrosion of iron.

Question 3

What is the word equation for the corrosion of tin and the rusting of metal.

Answer 3

Tin + Oxygen = Tin oxide

Question 4

What is an atom?

Answer 4

Small particles from which all substances are made of

Question 5

What is an element ?

Answer 5

A simple substance made up of only one type of atom.

Question 6

What is a compound?

Answer 6

A substance that can be split up because of the 2 or more elements formed together.

Question 7

What is a mixture?

Answer 7

Two or more substances jumbled together but not joined to each other. The substances can often be separated.

Question 8

Why are alloy often stronger than pure metals?

Answer 8

Alloys are made up of atoms of different sizes instead of being uniform. This means that the layers of atoms cannot slide over each other easily, making the whole alloy much stronger than any of the pure metals that the the alloy contains.

Question 9

What is an exothermic reaction?

Answer 9

A reaction in which energy stored in the reactants is transferred to the surroundings.

Question 10

What is an endothermic reaction?

Answer 10

A reaction in which energy is transferred to the surroundings to the reactants.

Question 11

What does thermal decomposition mean?

Answer 11

Thermal decomposition is a chemical reaction where heat is a reactant. Since heat is a reactant, these reactions are endothermic meaning that the reaction requires thermal energy to break the chemical bonds in the molecule.

Question 12

Describe the Bunsen flame colours and what each flame is used for

Answer 12

Quiet yellow flame- a safety flame which is not used because it leaves a layer of soot on surfaces.
Medium blue flame- used for heating
Noisy blue flame or roaring flame - used for heating quickly

Question 13

What are some properties of metals?

Answer 13

Malleable, Shiny, Good conductor, Not brittle

Question 14

What are some properties of non metals

Answer 14

Brittle, dull, poor conductor of heat and electricity

Question 15

What is the Law of conservation of mass?

Answer 15

Energy cannot be created or destroyed

Question 16

Describe a method to show how you would obtain a pure sample of salt from rock salt

Answer 16

1. Fold a circular filter paper in half
2. Fold the filter paper in half again to form a triangular shape
3. Open out one layer of the paper to form a cone
4. Place the filter paper cone in a filter funnel
5. Place the funnel in the neck of a conical flask
6. Stir the sand and water mixture so that all the sand is suspended in the water
7. Pour the sand and water mixture into the filter paper

Question 17

What is an independent variable?

Answer 17

It is a variable that stands alone and isn’t changed by other variables

Question 18

What is a dependent variable?

Answer 18

A dependent variable is what changes as a result of the independent variable manipulation in experiments

Question 19

What is a control variable?

Answer 19

A control variable is any variable that’s held constant in a research study. It’s not a variable of interest in the study, but it’s controlled because it could influence the outcomes.

Question 20

Why is a pencil line used in chromatography?

Answer 20

Because it does not dissolve in the solvent and affect the results.

Question 21

What is suspension?

Answer 21

A mixture of a solid or a liquid, where the solid bits are heavy enough to settle out if the mixture is left to stand

Question 22

What is a solvent?

Answer 22

A liquid in which a substance dissolves to make a solution

Question 23

What is a solute?

Answer 23

The substance that has dissolved in a liquid to make a solution

Question 24

What is a solution?

Answer 24

When a substance has dissolved into a liquid.

Question 25

Describe what you can see when a piece of magnesium is added to dilute hydrochloric acid

Answer 25

When magnesium is added to sulfuric acid, the hydrogen gas forms bubbles, while the magnesium sulfate stays in the solution. The solution is filtered to remove excess magnesium. Heating evaporates the water leaving solid salt magnesium sulfate.

Question 26

Describe the test for hydrogen gas

Answer 26

Place a lighted splint in a test tube containing the gas. If the gas is hydrogen, there will be a squeaky pop.

Question 27

Describe the test for carbon dioxide gas

Answer 27

The test for carbon dioxide uses an aqueous solution of calcium hydroxide (lime water). When carbon dioxide is shaken with or bubbled through lime water, the lime water turns milky (cloudy).

Question 28

What the test for oxygen gas

Answer 28

Oxygen supports combustion so a good method of testing for oxygen is to take a glowing splint and place it in a sample of gas, if it re-ignites the gas is oxygen.

Question 29

Use the particle model to explain how a hot air balloon rises as it is heated

Answer 29

The density of air at sea level is approximately 0.001g/cm cubed. Hot air balloons fly because the overall density of the whole balloon is less than than the air around it. The air inside is heated to make it expand and become less dense.