Isotopes And Moles

Question 1

What is the relative charge and mass of protons?

Answer 1

+1 relative charge

1 relative mass

Question 2

What is the relative charge and mass of electrons?

Answer 2

• 1 relative charge

0. 0005 relative mass

Question 3

What is the relative charge and mass of neutrons?

Answer 3

0/neutral relative charge

1 relative mass

Question 4

What are atoms of the same element with different numbers of neutrons called?

Answer 4

Isotopes

Question 5

What changes because of isotopes?

Answer 5

Physical properties (neutrons): mass, melting and boiling point, density
Chemical properties (electrons) stay the same

Question 6

What is the relative atomic mass?

Answer 6

The weighted average mass of the isotopes of the element

Question 7

What are isotopes?

Answer 7

Isotopes are different atomic forms of the same element, which have the same number of protons but a different number of neutrons

Question 8

What do all isotopes of a particular element have in common?

Answer 8

They have the same number of protons

Question 9

How do isotopes of a particular element differ from each other?

Answer 9

They have a different number of neutrons

Question 10

Why is the RAM not always a whole one number?

Answer 10

Because it is a weighted average

Question 11

E.g. Chlorine is made of two isotopes Cl-35 (75%) and Cl-37 (25%). What is the RAM/Ar?

Answer 11

75 x 35 + 25 x 37 / 100

Question 12

How do you work out the relative formula mass (Mr) of a compound?

Answer 12

Add together the relative atomic masses of atoms in a molecule, using the mass numbers

Question 13

How do you work out the percentage composition of an element?

Answer 13

n x (Ar of element) / Mr of compound x 100

Question 14

How do you work out the number of moles?

Answer 14

Mass / relative formula (atomic) mass

Question 15

What is the empirical formula?

Answer 15

The simplest whole number ratio of elements in a compound

Question 16

How do you find out the empirical formula?

Answer 16

Identify the elements (atoms)
Identify the mass of the elements (if % then assume out of 100g)
Calculate the moles by dividing the mass over atomic mass
Find mole ratio by dividing by the smallest number of moles
If answer is 1/2 multiply everything by 2

Question 17

How do you work out the volume?

Answer 17

Moles x 24

Question 18

How do you work out the moles using volume?

Answer 18

Volume (cm3) / 24,000
Or
Volume (dm3) / 24

Question 19

How do you work out percentage yield?

Answer 19

Write out equation and balance it
Calculate moles of the reactant
Using mole ratio, work out theoretical mass of product you should obtain (100% yield)
Divide actual mass obtained by theoretical mass obtained and x100 to get percentage yield

Question 20

What is the formula for percentage yield?

Answer 20

Mass/moles (use what’s given in question) of product collected / maximum theoretical mass / moles of product then x100

Question 21

What is the colour of precipitate of chloride?

Answer 21

White

Question 22

What is the colour of precipitate of bromide?

Answer 22

Cream

Question 23

What is the colour of precipitate of iodide?

Answer 23

Yellow

Question 24

What is the test for oxygen?

Answer 24

Oxygen relights a glowing spill

Question 25

Chlorine gas turns litmus paper what colour?

Answer 25

From blue to red then bleached white, it is acidic

Question 26

What is the test for carbon dioxide?

Answer 26

Turns limewater cloudy

Question 27

Ammonia gas turns litmus paper what colour?

Answer 27

From red to blue

Question 28

What are the steps to carrying out a flame test?

Answer 28

1) Put a small amount of the compound to be tested in a nichrome wire loop
2) Hold the loop inn the roaring blue flame of a Bunsen burner
3) Use the colour of the Bunsen burner to identify the metal ion in the compound

Question 29

What is the flame colour of lithium?

Answer 29

Crimson

Question 30

What is the flame colour of sodium?

Answer 30

Orange

Question 31

What is the flame colour of potassium?

Answer 31

Lilac

Question 32

What is the flame colour of calcium?

Answer 32

Red (brick red)

Question 33

What is the flame colour of copper?

Answer 33

Green