Science - Chemistry 1

Question 1

Formatting of a formula?

Answer 1

If there is more than one atom of each element, the number is always written after the symbol.

Question 2

can a physical state change of an atom?

Answer 2

Yes it can change from solids, liquids and gases

Question 3

Reactants

Answer 3

A starting material in a chemical reaction

Question 4

Word Equation

Answer 4

an equation in which the reactants and products in a chemical reaction are represented by words

Question 5

Chemical Equation

Answer 5

an equation that uses chemical formulas and symbols to show the reactants and products in a chemical reaction

Question 6

Hydrocarbons

Answer 6

Compounds composed of only carbon and hydrogen

Question 7

Limewater

Answer 7

Test for carbon dioxide

Question 8

Hydrogen + Oxygen ->

Answer 8

water

Question 9

Hydrogen fuel cell

Answer 9

generates electricity by reacting hydrogen with oxygen

Question 10

Oxidation

Answer 10

A chemical change in which a substance combines with oxygen, as when iron oxidizes, forming rust

Question 11

metal + oxygen ->

Answer 11

Metal oxide

Question 12

Conservation of mass

Answer 12

the principle stating that matter is not created or destroyed during a chemical reaction

Question 13

Incomplete combustion

Answer 13

When a fuel burns in insufficient oxygen, producing carbon monoxide as a product.

Question 14

Catalytic converter

Answer 14

a device that reduces carbon monoxide emissions from vehicles.

Question 15

4 main effects of global warming?

Answer 15

Temperature, coastal flooding, rainfall and plants

Question 16

without and with greenhouse effects temperature on earth

Answer 16

-18 degrees if no greenhouse effect
+14 with greenhouse effect

Question 17

physical state change

Answer 17

The chemical formula is the same but the state (solid, liquid gas) is different

Question 18

CH4 + 02 -> ?

Answer 18

CO2 + 2 H2O

Question 19

chemical state change

Answer 19

The chemical formula changes and gives off heat, light or gas and is difficult to reverse

Question 20

alkali + water ->

Answer 20

metal hydroxide + hydrogen

Question 21

properties of alkali

Answer 21

It reacts with water and the metal is very soft

Question 22

properties of halogens

Answer 22

They are reactive non-metals, they react vigorously with metals. low boiling and melting points.

Question 23

properties of noble gases

Answer 23

They are very unreactive non - metals

Question 24

Describe the reactions of when Lithium, Potassium and Sodium reacted with water

Answer 24

Li – Hydrogen given off quite slowly.
Na – Hydrogen given off quickly and the metal melted into a sphere.
K - Hydrogen given off very quickly, the metal melted and had a small lilac flame.

Question 25

endothermic and exothermic reaction

Answer 25

endothermic reactions absorb energy while exothermic reactions release energy.

Question 26

what are the 3 things required to start a fire

Answer 26

Fuel, Heat and Oxygen

Question 27

Why shouldn't we put water on burning oil

Answer 27

The water sinks through the hot oil and turns it into steam. The steam rises quickly, pushing burning oil out of the way and making the fire spread out

Question 28

Why should we not put water on an electrical fire

Answer 28

Water conducts electricity and you could get an electric shock. To put out the fire you should use a powder or a carbon dioxide gas extinguisher.

Question 29

Independent and dependent variables

Answer 29

An independent variable is the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable. A dependent variable is the variable being tested and measured in a scientific experiment.

Question 30

carbon footprint

Answer 30

a carbon footprint is a measure of the masses of greenhouse gases put into the atmosphere by people or organizations