Amount Of Substance

Question 1

Define relative atomic mass (Ar)?

Answer 1

RAM is the average mass of an atom of an element compared with 1/12 of the mass of an atom of carbon-12

Question 2

What is the formula for calculating Ar?

Answer 2

Ar= Average mass of an element
————————————————
1/12 the mass of 1 atom of carbon-12

Question 3

Define relative atomic mass (Mr)?

Answer 3

Mr is the sum of the Ar’s of all the atoms in a molecule

Question 4

What is the formula to calculate Mr?

Answer 4

Mr = average mass of 1 molecule of an element or compound/ one twelfth mass of 1 atom of carbon 12

Question 5

What is 1/12 the mass of 1 carbon-12 atom?

Answer 5

1

Question 6

To calculate the relative formula mass (Mf) what is the formula?

Answer 6

It’s the same as for the Mr

Question 7

One mole of carbon-12 atoms has a mass of?

Answer 7

12.000g

Question 8

State Avogadro’s constant?

Answer 8

6.023 x 10 23( the power)

Question 9

State the ideal gas equation

Answer 9

PV=nRT
P=pressure
V=volume
n=moles
R=gas constant
T=temperature

Question 10

State the gas constant

Answer 10

8.31JK-1mol-1

Question 11

Why can gas be liquified ( under the right conditions)?

Answer 11

In ideal gas there are no intermolecular forces so particles are not attracted to each other whereas the in real gas attractive intermolecular forces divert the paths of particles.

Question 12

What is Boyle’s law?

Answer 12

At constant temperature (T) the volume (V) of a fixed mass of gas is said to be inversely proportional to the pressure (p) applied to it
P x V= constant

Question 13

State Charles law?

Answer 13

At constant pressure the volume of a fixed mass of gas is proportional to its temperature
V= constant x T

Question 14

What is the absolute zero temperature and how was it proved?

Answer 14

-273.15*C
FOUND by plotting volumes of most gases against temp and extrapolating which shows that they all reach zero volume at the same temperature

Question 15

You must always convert to Kelvin (K) when doing idea gas equations, how do you do that?

Answer 15

+273 to anything with a degrees Celsius

Question 16

Define empirical formula?

Answer 16

The simplest whole number ratio of atoms of each element that are in a compound

Question 17

What is theoretical yield?

Answer 17

The expected quantity of a product from a perfect chemical reaction

Question 18

Define Actual yield ?

Answer 18

The actual amount of product produced after a reaction

Question 19

What is the formula to calculate percentage yield?

Answer 19

Percentage yield = (actual yield/ theoretical yield ) x 100

Question 20

What is percentage atom economy?

Answer 20

A way to compare the maximum mass of a product that can be obtained with the mass of the reactants

Question 21

What is the formula for percentage atom economy?

Answer 21

PAC= (molecular mass of desired product/ sum of molecular masses for all reactants) x 100

Question 22

Define spectator ions?

Answer 22

Ions that appear unchanged on both sides of the ionic equations

Question 23

How do you calculate conc with moles and volume?

Answer 23

Conc= moles/vol

Question 24

What is a volumetric solution and how do you make it?

Answer 24

A solution where the precise conc is known.
Calculate the Mf then dissolve a known volume of the solution which will be the conc