Water is always on the move. Rain falling today may have been water in a distant ocean days before. And the water you see in a river or stream may have been snow on a high mountaintop. Water is in the atmosphere, on the land, in the ocean, and underground. It moves from place to place through the water cycle.
Where's the water?
There are about 1.4 billion km3 of water (336 million mi3 of water) on Earth. That includes liquid water in the ocean, lakes, and rivers. It includes frozen water in snow, ice, and glaciers, and water that’s underground in soils and rocks. It includes the water that’s in the atmosphere as clouds and vapor.
If you could put all that water together – like a gigantic water drop – it would be 1,500 kilometers (930 miles) across.
Answer:
If 51.8 of Pb is reacting, it will require 4.00 g of O2
If 51.8 g of PbO is formed, it will require 3.47 g of O2.
Explanation:
Equation of the reaction:
2 Pb + O2 → 2 PbO
From the equation of reaction, 2 moles of lead metal, Pb, reacts with 1 mole of oxygen gas, O2, to produce 2 moles of lead (ii) oxide, PbO
Molar mass of Pb = 207 g
Molar mass of O2 = 32 g
Molar mass of PbO = 207 + 32 = 239 g
Therefore 2 × 207 g of Pb reacts with 32 g of O2 to produce 2 × 239 g of PbO
= 414 g of Pb reacts with 32 g of O2 to produce 478 g of PbO
Therefore, formation of 51.8 g of PbO will require (32/478) × 51.8 of O2 = 3.47 g of O2.
If 51.8 of Pb is reacting, it will require (32/414) × 51.8 g of O2 = 4.00 g of O2
