Chapter 5- The Mole

Question 1

What is the standard for the mole?

Answer 1

Carbon-12

Question 2

What is the mass spectrometre used for?

Answer 2

Seperating different types of atoms due to their mass.

Question 3

What can the mass spectrometre tell us about?

Answer 3

• No. of isotopes in a given sample of element
• Relatice isotopic mass
• Percentage abundance of Isotopes

Question 4

Define the relative atomic mass

Answer 4

Average mass of one atom, given that the isotopic mass has been taken into account. (average)

Question 5

Define Realtive Abundance of an Isotope

Answer 5

How present that isotope is compared to others

Question 6

Formula for relative atomic mass

Answer 6

Ar= (RIM of first isotope x abundance) + (RIM of second isotope x abundance) / 100

Question 7

What is avogagros number?

Answer 7

6.02 x 10^23

Question 8

How many atoms are there in one mole of an element?

Answer 8

Avogadros number

Question 9

What is the formula for percentage composition?

Answer 9

% of x in a compound containing x = mass of x in 1 mol/ molar mass of compound x 100

Question 10

Steps for the Empirical Formula

Answer 10

1. Write down symbols of the element that is present
2. Assume that the mass of the sample is in grams
3. Convert masses to moles
4. Find the simplest whole number ratio and divide all by the smallest.
5. If nesscary multiply by a factor to convert all the numbers to whole

Question 11

What are the parts of the first mole pyramid?

Answer 11

On the top: m= mass

On the bottom: n= no. of mole and Mr = Molar mass

Question 12

What are the parts of the second mole pyramid?

Answer 12

On the top: N= no. of particles

On the bottom: n= no. of moles and Na= Avogadros Number

Question 13

Steps to find the molecular formula

Answer 13

Find the Empirical Formula Mass
Molecular Mass should be given to you
Then divide the molecular mass by the empirical formula mass
This should give you a ratio
Use this ratio to and times it by the empirical formula