amount of a substance

Question 1

There is a number that is important to chemists, what is the name?

Answer 1

Avogadro’s Number

Question 2

What is the value of avogadro’s number

Answer 2

6.02 x 10 to the power of 23

Question 3

What does the mole contain?

Answer 3

6.02 x 10 to the power of 23

Question 4

Ways of calculating moles

Answer 4

mass: moles/ molar mass
solution: concentration x volume

gas@RTP: volume/24000

gas not @RTP: (pressure x volume)/ (gas constant x temperature)

Question 5

What is molar mass (relative formula mass)?

Answer 5

The molar mass or relative formula mass of a compound is the mass of one mole of that substance

Question 6

What is the empirical formula?

Answer 6

the simplest whole number ratio of atoms in a substance

Question 7

Steps of the empirical formula

Answer 7

1) calculate the amount in moles of each of the elements present.
2) work out ratio of the elements present
3) Then calculate the molecular formula.

Question 8

Why do equations need to be balanced?

Answer 8

they need to be balanced in order to remain true with the basic law that atoms cannot be created or destroyed in a reaction, they are only arranged.

Question 9

Acid-base neutralisation

Answer 9

When an acid and base(chemical opposites) react two compounds are formed. salt and water

Question 10

Thermal Decomposition

Answer 10

A compound being heated to a high temperature then the breakdown into two or more products occur

Question 11

acid/metal reaction

Answer 11

They produce the same products. Salt and hydrogen gas. lit splint, squeaky pop as hydrogen ignites.

Question 12

acid/carbonate reaction

Answer 12

will react similar way as an acid and base, however the carbonate will produce carbon dioxide.

Question 13

precipitation reaction

Answer 13

two aqueous equations will react to produce an insoluble solid

Question 14

combustion reaction

Answer 14

In order for anything to burn, oxygen is required. This will produce carbon dioxide and water.

Question 15

What is the relationship between reactions called?

Answer 15

Stoichiometry

Question 16

Stoichiometry Steps

Answer 16

1) Calculate the moles
2) calculate the ratio to balance it
3) Rearrange the formulae

Question 17

The ideal gas law

Answer 17

This law describes how gases would behave at different temperatures and pressure.

Question 18

Units of pressure, volume and temperature.

Answer 18

pressure= pascals
volume= cubic metres
temperature= kelvin

Question 19

With an acid base titration, what will be used to indicate the end point.

Answer 19

An indicator

Question 20

What do indicators do? as they are special chemicals.

Answer 20

They change colour when they are at a different pH

Question 21

What will indicate rapid changes?

Answer 21

titration curve.

Question 22

Equivalence Point

Answer 22

the point in a titration where the volume of one solution exactly matches the volume of the other solution.

Question 23

Titration calculation steps e.g. nitric acid

Answer 23

1) calculate the number of moles.
2) calculate the amount of moles used
3) convert the volume of titration reading in dm3
4) Calculate the concentration moles/volume