Moles

Question 1

Formula for moles

Answer 1

moles = mass/mr

Question 2

What is an isotope

Answer 2

An atom of the same element with the same number of protons but different number of neutrons

Question 3

What is atomic mass

Answer 3

The number of protons + neutrons

Question 3

What is atomic number

Answer 3

The number of protons or electrons

Question 4

What is relative atomic mass

Answer 4

The average mass of an element’s atom compared to the mass of a carbon-12 atom. It is calculated using the atomic mass of its isotopes and their abundancies

Question 5

What are the steps of finding the mass of a product from the mass of a reactant

Answer 5

1. Convert the mass of the reactant to moles
2. Find the ratio between the reactant and the product (the coefficient)
3. From this ratio, work out the moles of the product
4. Convert this moles back to mass

Question 6

What is a limiting reagent

Answer 6

A reaction will stop when one of its reactants is used up. The reactant that is used up is the limiting reagent

Question 7

What does it mean if a reactant is in excess

Answer 7

A reactant is described as being in excess if there is some left over after the reaction has finished

Question 8

How do you figure out which is the limiting reagent

Answer 8

1. Convert both reactants to moles using moles = mass/mr
2. Look at the ratio between the 2 reactants
3. Figure out which mole is less than the number in the ratio
4. This will be your limiting reagent
5. You can then use it to work out the mass of the product formed