Reactions - Week 10

Question 1

What is stoichiometry?

Answer 1

The measurement of the combining proportions of chemical elements and compounds.

Question 2

What is molar mass?

Answer 2

1 mole of any substance with a definite formula has a mass in g numerically equal to its relative formula. In M g mol ^-1

Question 3

What is the definition of 1 atomic mass unit?

Answer 3

Defined as 1/12th x mass of 1 atom of 12C which is (12g exactly of 12C) / Na

Gives 1 Da = 1.66054 x 10 -27 kg

Question 4

What is the equation linking moles, density, volume and Mr?

Answer 4

n = pV/M

p = density

Question 5

What is empirical formula?

Answer 5

The simplest ratio of numbers of atoms of each element involved in a compound. Same as the simplest ratio of moles of atoms of each element.

Question 6

What is the equation for empirical formula?

Answer 6

Mass of element in sample of compound / Molar atomic mass of element

Question 7

What is the equation for molecular formula?

Answer 7

= n x empirical formula

where n is an integer

Question 8

How do you work out the value of n?

Answer 8

n = molar mass / molar mass for empirical formula unit