The teacher would use a dozen eggs and a dozen jellybeans to describe a mole.
A mole is simply a <em>number</em> of things.
Just as a dozen eggs is the <em>same number</em> as a dozen jellybeans, a mole of eggs is the <em>same number</em> as a mole of jellybeans.
Weight percentage of nitrogen can be calculated using the following rule:
weight percentage of nitrogen = (weight of nitrogen / weight of urea) x 100
From the periodic table:
molecular mass of carbon = 12 grams
molecular mass of nitrogen = 14 grams
molecular mass of hydrogen = 1 grams
molecular mass of oxygen = 16 grams
therefore:
mass of nitrogen in urea = 2(14) = 28 grams
mass of urea = 12 + 2(14) + 4(1) + 16 = 60 grams
Substitute with the masses in the equation to get the percentage:
weight percentage of nitrogen = (28/60) x 100 = 46.667%
Answer:
An aquifer is a layer of porous substrate that contains and transmits groundwater. ... The upper level of this saturated layer of an unconfined aquifer is called the water table or phreatic surface. Below the water table, where in general all pore spaces are saturated with water, is the phreatic zone.
12. When the sun is farthest north or south of the equator, the even is called solstice. When it is farthest to the north, it is called summer solstice and when it farthest to the south it is called winter solstice .
13. When neither hemisphere is tilted toward nor away form the sun, it is called equinox. At this time, daylight and night time is as long as each other, or they are both 12 hours long in both hemisphere.
