A divalent metal oxide contains 60% of metal. What is atomic weight of metal?
wt of metal= 60 g
wt of oxygen= (100-60) g= 40 g
Eq. wt. of metal = wt. of metal/ wt of oxygen* 8
= 12
As metal is divalent, At. wt= Eq. wt* valency= 12*2 = 24
Calculate mass in gram of
a. two atom of carbon
b. three molecules of hydrogen
Two atoms of Carbon:
1 mole of carbon = 12g
1 mole of carbon = 6.022 x 1023 carbon atom
Thus,
6.022 x 1023 carbon atom has mass 12g
2 carbon atom has mass = 3.98 x 10-23 g carbon.
Three molecules of hydrogen:
1 mole of hydrogen molecule = 2g
1 mole of hydrogen molecule = 6.022 x 1023 hydrogen molecule
Thus,
6.022 x 1023 hydrogen molecule has mass 2g hydrogen.
3 hydrogen molecules has mass = 9.96 x 10-24g