1c.1 comparing masses of substances

Question 1

how did the term of relative atomic mass come

Answer 1

in the 19th century, the sciences realized that the elements had different masses. they couldn’t weigh the individual mass but could compare the masses of the elements together. the scientists found out that the hydrogen atom is the smallest in mass and has a relative atomic mass of 1. after that they started finding out the Ar of each element by comparing it with hydrogen, for example, the silicon atom was weighed 2x that the nitrogen atom and nitrogen was 14 times heavier than the hydrogen atom there for the nitrogen atom Ar was 12 and silicon Ar was 28, later on, the scientist discovered the isotope carbon 12. after that the Ar was the mean mass average of an atom compared to 1/12 mass of an atom of carbon 12

Question 2

how can we find moles by using molar mass

Answer 2

amount of mol = mass of a substance in g/kg/ molar mass in gmol-1 or kgmol-1

Question 3

what is Avagadro constant

Answer 3

It is the number of particles in one mole of a substance and can be written as: 6.02 x 10^23 and has the symbol of L

Question 4

what is an example of Avagadro constant

Answer 4

how many H2O molecules are there in 1,25g of water
n= 1.25/18 = 0.0694
6.02x 10^23 x 0.0694 = 4.18 x 10^22

Question 5

what is the molar mass

Answer 5

mass per mole of a substance and Molar mass = Ar, Mr, and relative atomic formula