Earth contains huge quantities of water in its oceans, lakes, rivers, the atmosphere, and believe it or not, in the rocks of the inner Earth. Over millions of years, much of this water is recycled between the inner Earth, the oceans and rivers, and the atmosphere. This cycling process means that freshwater is constantly made available to Earth's surface where we all live. Our planet is also very efficient at keeping this water. Water, as a vapor in our atmosphere, could potentially escape into space from Earth. But the water doesn't escape because certain regions of the atmosphere are extremely cold. (At an altitude of 15 kilometers, for example, the temperature of the atmosphere is as low as -60° Celsius!) At this frigid temperature, water forms solid crystals that fall back to Earth's surface.
Many people live faraway from freshwater sources. They need to carry their water home.
While our planet as a whole may never run out of water, it's important to remember that clean freshwater is not always available where and when humans need it. In fact, half of the world's freshwater can be found in only six countries. More than a billion people live without enough safe, clean water.
Also, every drop of water that we use continues through the water cycle. Stuff we put down the drain ends up in someone or something else's water. We can help protect the quality of our planet's freshwater by using it more wisely.
Unit of M is also mole/L, where mole is the moles of solute and L is the volume of the solution. The latter is given: 158 mL or 0.158 L. So we need to find out the moles of NH4Br.
Moles of NH4Br = Mass of NH4Br/molar mass of NH4Br = 17.0g/(14+1*4+79.9)g/mol = 0.1736 mole.
So, the molarity of the solution = 0.1736mole/0.158L = 1.10 mole/L = 1.10 M
Answer:
The mass, CO2 and CO3 from the limestone sample is discussed below in details.
Explanation:
(A) mass loss of sample of limestone after 20 min
= 0.8437g-0.5979g = 0.2458 g
From the given reaction of limestone, 2 mol of the sample gives 2 moles of CO 2.
Therefore
184.4 g ( molar mass of limestone) gives2× 44 g of carbon dioxide.
1 g of sample gives 88/184.4 g of carbon dioxide
Hence 0.2458 g sample gives
= 88/184.4 × 0.2458 g = 0.117 g carbon dioxide
(B) mole of CO 2 lost = weight/ molar mass
= 0.117 g / 44 g/mol =0.0027 mole
(C). 1 mol of limestone contain 2 mol of carbonate ion
From the reaction we know that carbonate ion of limestone is converted into carbondioxide
Hence lost carbonate ion = 0.2458 g
(D) we know that
1 mol limestone contain 1mol CaCO 3
Hence in sample present CaCO 3
= 1mole / 184.4 g × 0.8437 g= 0.00458 mol CaCO3
