Avogadros and particles vs grams

Question 1

How many molecules in a mole?

Answer 1

6.023x10^23

Question 2

What is the molecular weight of water?

Answer 2

18mu

Question 3

what is the molar mass of water

Answer 3

18 grams/mol

Question 4

What is the number of grams per one mole of atoms?

Answer 4

12.01 grams per mole

Question 5

1.17g of sodium chloride was dissolved in water to make 500cm3 of solution. Find the concentration in mol dm^-3

Answer 5

Na = 23.0. Cl=35.5

The mass of 1 mole of sodium chloride, NaCl is 23.0 + 35.5 = 58.5g
Concentration = n/v = 0.020/0.500 = 0.040 mol dm^-3.

Question 6

How many moles are present in 25.0cm3 of a solution of concentration 0.10 mol dm^-3?

Answer 6

n=c(dm^-3)v(cm3)/1000
n=cv/1000
=0.0025mol

Question 7

How many moles are present in 5.0cm3 of a solution of concentration 0.20 mol dm^-3?

Answer 7

n=c(dm^-3)v(cm3)/1000
n=cv/1000
=0.001mol

Question 8

How many moles are present in 50.0cm3 of a solution of concentration 0.20 mol dm^-3?

Answer 8

n=c(dm^-3)v(cm3)/1000
n=cv/1000
=0.01mol

Question 9

How many moles are present in 50.0dm3 of a solution of concentration 0.20 mol dm^-3?

Answer 9

n=c(dm^-3)v(dm^3)
n=cv
=10mol