Chemistry Calculations

Question 1

What is ‘the mole’ used for?

Answer 1

IS what chemists use to count particles

Question 2

as we cannot count out individual atoms molecules, ions ext what do we use?

Answer 2

Masses of solids and volumes of liquids and gases and solutions

Question 3

One mole of carbon contains how many molecules of carbon?

Answer 3

6.02x10 to the power of 23

Question 4

We use the periodic table to find out the relative atomic mass for each element. What is the relative atomic mass

Answer 4

the mass in grams of 1 mole of the atoms of that element

Question 5

What is the mathematical elements to fine the moles?

Answer 5

M / Ar

Mass in grams / relative atomic mass

Question 6

what is Mr?

Answer 6

Relative molecular mass or relative formula mass

Question 7

What are the steps for the calculation to find the Mr?

Answer 7

1) must have correct formula
2) write down the number of atoms of each element
3) Add up relative atomic mass for each atom of each element in the formula

Question 8

Mr for NaOH

Answer 8

(1xNa) + (1xo) + (1xH)
(1x23) + (1x16) + (1x1)
Mr=40

Question 9

What is used to calculate percentage composition?

Answer 9

Mr and Ar to calculate the percentage composition by mass of an element in a compound

Question 10

what are the steps to calculate the percentage composition?

Answer 10

1) calculate Mr
2) look at calc for step 1 - identity the number of atoms of the element asked for
3) add up mass due to this element
4) calculate % =
mass due to element/Mr x 100