Mole Calculations and Titrations

Question 1

What is relative molecular mass?

Answer 1

The weighted mean mass of a molecule compared with one-twelfth of the mass of an atom of carbon-12. It is used for simple molecules.

Question 2

What is relative formula mass?

Answer 2

The weighted mean mass of a formula unit compared with one-twelfth of the mass of an atom of carbon-12. It is used for compounds with giant structures.

Question 3

What is relative isotopic mass?

Answer 3

The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12.

Question 4

What is amount of substance?

Answer 4

The quantity whose unit is the mole, used as a means of counting atoms.

Question 5

What is a mole?

Answer 5

The unit for amount of substance.

Question 6

What is the Avogadro constant?

Answer 6

The number of particles per mole (6.02 ✕ 10²³ mol⁻¹).

Question 7

What is molar mass?

Answer 7

The mass per mole of a substance.

Question 8

What is empirical formula?

Answer 8

The simplest whole-number ratio of atoms of each element present in compound.

Question 9

What is molecular formula?

Answer 9

The actual number of atoms of each element in a molecule.

Question 10

What is a molecule?

Answer 10

A small group of atoms held together by covalent bonds.

Question 11

What is molar volume? What is it at RTP?

Answer 11

The volume per mole of a gas. At RTP, it is approximately 24.0 dm³ mol⁻¹.

Question 12

What is concentration of a solution?

Answer 12

The amount of solute dissolved per 1 dm³ of solution.

Question 13

What is a standard solution?

Answer 13

A solution of known concentration.

Question 14

What is stoichiometry?

Answer 14

The molar relationship between the relative quantities of substances taking part in a reaction.

Question 15

What is the colour of methyl orange in acid, base, and the end point colour?

Answer 15

Acid: red
Base: yellow
End point: orange

Question 16

What is the colour of bromothymol blue in acid, base, and the end point colour?

Answer 16

Acid: yellow
Base: blue
End point: green

Question 17

What is the colour of phenolphthalein in acid, base, and the end point colour?

Answer 17

Acid: colourless
Base: pink
End point: pale pink (when base added to acid) or colourless (when acid added to base)

Question 18

How do you carry out a titration?

Answer 18

1) Use a pipettes to add a measured volume of one solution to a conical flask.
2) Place the other solution in a burette.
3) Add the solution in the burette to the solution in the conical flask until the end point of the titration, and measure the volume of solution added from the burette.

Question 19

What is relative atomic mass?

Answer 19

The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.